A. Reaction Mechanisms and Catalysis (1) proximity effect (2) acid-base catalysts (3) electrostatic (4) functional groups (5) structural flexibility
|
|
- Roger Hamilton
- 6 years ago
- Views:
Transcription
1 (P&S Ch 5; Fer Ch 2, 9; Palm Ch 10,11; Zub Ch 9) A. Reaction Mechanisms and Catalysis (1) proximity effect (2) acid-base catalysts (3) electrostatic (4) functional groups (5) structural flexibility B. Active Site Investigations (1) kinetic studies (2) detection of intermediates (3) x-ray crystallographic studies (4) chemical modification of amino acid side chains (5) site-directed mutagenesis studies C. Specific enzymes (1) lactate dehydrogenase and alcohol dehydrogenase (2) ribonuclease A (3) triose phosphate isomerase (4) amino acyl trna synthetases (5) carbonic anhydrase 77
2 (1) Proximity effect--enzymes bring reacting species close together -an enzyme can accelerate a rxn between two species simply by holding the two reactants close together in an appropriate orientation -intramolecular rxns between groups that are tied together in a single molecule are faster than the corresponding intermolecular rxns between two independent molecule, eg., cyclization of succinic acid to form succinyl anhydride c.f. formation of acetic anhydride from two molecules of acetic acid -difference in rates are 3-4 orders of magnitude (intramolecular> intermolecular) -effect is due mostly to the differences between the entropy changes that accompany the inter- and intramolecular rxns -formation of P involves a much larger loss of translational and rotational entropy in the intermolecular rxn 78
3 -a negative change in entropy increases both the overall free energy change in the rxn (ΔG = ΔH -TΔS) and the activation free energy (ΔG = ΔH - TΔS ) for the formation of the transition state -in the intramolecular rxn much of this entropy decrease has already occurred during the preparation of the reagent -enzymes that take catalyze intermolecular rxns take advantage of the proximity effect by binding the reactants close together in the active site, so that the reactive groups are oriented appropriately for the rxn -once the substrates are fixed this way the rxn behaves kinetically like an intramolecular process -the entropy decrease associated with the formation of the transition state has been moved to an earlier step, the binding of the substrates to form the E-S complex (2) Acid-Base Catalysis -task of a catalyst is to make a potentially reactive group more reactive by increasing its intrinsic electrophilic or nucleophilic 79
4 character -simplest way is to add or remove a proton eg., hydrolysis of an ester -hydrolysis of an ester in neutral aqueous solution can occur if the O atom of H 2 O, acting as a nucleophile, attacks the positively charged carbon -initial product is an intermediate where the carbon atom has four substituents in a tetrahedral arrangement -rxn is completed by the rapid breakdown of the tetrahedral intermediate to release the alcohol -H 2 O is intrinsically a comparatively weak nucleophile, and its rxn with esters in the absence of a catalyst is very slow -hydrolysis of esters occurs much more rapidly at high ph, when the negatively charged OH - replaces H 2 O as the reactive nucleophile -the nucleophilic character of H 2 O itself can be increased by 80
5 interaction with a basic group other than OH - where the base offers a pair of electrons to one of the protons of the H 2 O and increases the electron density of the oxygen -general base--used to describe any substance that is capable of binding a proton in aqueous soln -enzymes use a number of functional groups to fill this role (necessary since the [OH - ] at physiological ph limits its availability] -only requirement is that the base start out in the unprotonated form, which means that the ambient ph must be above the pk a of the conjugate acid -candidates include: basic groups from the ionizable or polar amino acid side chains, an amino-terminal NH 2 group, a carboxyl-terminal carboxylate ion, or from the oxygen or nitrogen atom of a peptide bond -the pk a of these groups can vary over a considerable range environment 81
6 -using a general base rather than OH - has the advantage that the basic group that is provided by the protein can be positioned precisely with respect to the substrate in the active site, allowing the proximity effect to come into play -hydrolysis of an ester can also be catalyzed by an acid where the acid donates a proton to the oxygen of the ester's carbonyl group, increasing the positive charge on the carbon and increasing the susceptibility of the ester to attack by a nucleophile -general acid--any substance that is capable of releasing a proton, and enzymes almost always use such proton donors in preference to H + or OH - because a general acid can operate at moderate ph and is easy to fix in position -requirement is that the ph be below the pk a (3) Electrostatic interactions --enzymes act by stabilizing the distribution of electrical charge in transition states -suppose the active site of an enzyme included a positively charged amino acid side chain, such as Lys or Arg, located near the oxygen atom of a carbonyl group. A fixed positive charge 82
7 in this region would favor the formation of the tetrahedral intermediate, even if there were no transfer of a proton from the charged species to the oxygen. A fixed negative charge in the region of the nucleophile would have a similar effect. The interactions of such fixed charges are termed electrostatic effects. -as a reacting substrate is transformed into a transition state, the changing charges on its atoms interact with the charges on all of the other atoms in the surrounding protein, and also with the charges on any nearby water molecules -the energy difference between the initial state and the transition state thus depends critically on the details of the protein structure -modern computational techniques, when taken with the wealth of structural information from X-ray crystallography and other biophysical studies, have made it possible to calculate the contributions that various components of an enzyme's active site make to the activation free energy (ΔG ), and to predict quantitatively how ΔG might be altered by modifications of the protein 83
8 -can be tested experimentally by modifying the gene that encodes the protein (site-directed mutagenesis) (4) Nucleophilic/Electrophilic Catalysis (a) Nucleophilic Catalysis--strategy is to use stronger nucleophilic groups (than water) as part of the enzyme's active site -HOCH 2 group of a serine residue often used as a nucleophile -instead of immediately yielding the free COOH, the breakdown of the tetrahedral intermediate yields an intermediate ester that is covalently attached to the enzyme -the acyl-enzyme intermediate must be hydrolyzed by a second rxn in which H 2 O is the nucelophile -proteolytic enzymes (serine proteases) work in this way -two step pathway requires that the intermediate be more susceptible to nucleophilic attack by H 2 O than by the original ester or amide 84
9 -nucleophilic groups on enzymes participate in a variety of other types of rxn in addition to hydrolytic rxns, eg., acetoacetic acid decarboxylase -rxn proceeds by the formation of a Schiff base intermediate, in which the substrate is covalently attached to the ε-amino group of a lysine residue at the enzyme's active site -this intermediate is formed by a nucleophilic attack of the amino group on the carbonyl carbon, followed by the splitting out of H 2 O -protonation of the nitrogen atom of the Schiff base introduces a positive charge that pulls electrons from the nearby carboncarbon bond, causing decarboxylation -this is an extreme example of an electrostatic effect where the enzyme introduces a charged group into the substrate itself -basic feature of this mechanism is the formation of an intermediate state in which the substrate is covalently attached 85
10 to a nucleophilic group on the enzyme -the -CH 2 SH of cysteine is often used as a nucleophile also -the COOH of Asp and Glu participate in rxns involving the hydrolysis of ATP and -the imidazole ring of His can play a similar role -some enzymes use coenzymes: thiamine, biotin, pyridoxamine, or tetrahydrofolate as additional nucleophilic reagents (b) Electrophilic Catalysis--numerous enzymes use bound metal ions to form complexes with substrates -metal ion functions as an electrophilic group -eg., carbonic anhydrase--contains a Zn 2+ ion in the active site and forms a complex with the carbonyl oxygen atom of the aldehyde or peptide substrate -withdrawal of electrons by the Zn 2+ increases the partial positive charge on the carbonyl carbon atom and promotes the rxn of carbon with a nucleophile 86
11 (5) Structural Flexibility--some enzymes undergo major structural rearrangements when they bind substrates or inhibitors -eg., hexokinase ATP + glucose ADP + glucose-6-phosphate -hexokinase binds glucose, it undergoes a structural organization that brings together the elements of the active site -the enzyme literally closes like a set of jaws around the substrate referred to as an induced fit -carboxypeptidase A undergoes a major structural change when it binds its substrate -rearrangement of the protein pulls the hydrophobic part of the substrate out of the aqueous soln by surrounding it with nonpolar portions of the protein -advantages: (1) maximizes the favorable entropy change associated with removing a hydrophobic molecule from H 2 O (2) allows enzyme to intensify the electrostatic effects that promote the formation of the transition state (the substrate is 87
12 forced to respond to the directed electrostatic fields from the enzyme's functional groups, instead of the disordered fields from the solvent -structural change can help to explain the high specificity of some enzymatic rxns; eg., hexokinase undergoes a structural change upon binding glucose which promotes the binding of the other substrate (ATP) -ATP doesn't bind unless glucose is already present in the catalytic site -if ATP were to bind in the absence of glucose, the enzyme might have a tendency to catalyze the transfer of phosphate from ATP to water, resulting in a wasteful loss of ATP: ATP + H 2 O ADP + Pi -X-ray crystal structure of an enzyme give only static snapshots of the molecules, which can be very flexible -vibrations and rotations involving only a few atoms to s 88
13 -larger motions, i.e., flipping of aromatic rings 10-9 to 10-8 s -major reorganizations 10-6 to 10-3 s -all these can be important for catalysis 89
Chapter 15: Enyzmatic Catalysis
Chapter 15: Enyzmatic Catalysis Voet & Voet: Pages 496-508 Slide 1 Catalytic Mechanisms Catalysis is a process that increases the rate at which a reaction approaches equilibrium Rate enhancement depends
More informationIt s the amino acids!
Catalytic Mechanisms HOW do enzymes do their job? Reducing activation energy sure, but HOW does an enzyme catalysis reduce the energy barrier ΔG? Remember: The rate of a chemical reaction of substrate
More information4 Examples of enzymes
Catalysis 1 4 Examples of enzymes Adding water to a substrate: Serine proteases. Carbonic anhydrase. Restrictions Endonuclease. Transfer of a Phosphoryl group from ATP to a nucleotide. Nucleoside monophosphate
More informationKey Concepts.
Lectures 13-14: Enzyme Catalytic Mechanisms [PDF] Reading: Berg, Tymoczko & Stryer, Chapter 9, pp. 241-254 Updated on: 2/7/07 at 9:15 pm movie of chemical mechanism of serine proteases (from Voet & Voet,
More informationLecture 15: Enzymes & Kinetics. Mechanisms ROLE OF THE TRANSITION STATE. H-O-H + Cl - H-O δ- H Cl δ- HO - + H-Cl. Margaret A. Daugherty.
Lecture 15: Enzymes & Kinetics Mechanisms Margaret A. Daugherty Fall 2004 ROLE OF THE TRANSITION STATE Consider the reaction: H-O-H + Cl - H-O δ- H Cl δ- HO - + H-Cl Reactants Transition state Products
More informationAcid/Base catalysis Covalent catalysis Metal ion catalysis Electrostatic catalysis Proximity and orientation Preferential binding of the transition
Enzyme catalysis Factors that contribute to catalytic power of enzymes Acid/Base catalysis Covalent catalysis Metal ion catalysis Electrostatic catalysis Proximity and orientation Preferential binding
More informationCatalysis. Instructor: Dr. Tsung-Lin Li Genomics Research Center Academia Sinica
Catalysis Instructor: Dr. Tsung-Lin Li Genomics Research Center Academia Sinica References: Biochemistry" by Donald Voet and Judith G. Voet Biochemistry" by Christopher K. Mathews, K. E. Van Hold and Kevin
More informationC a h p a t p e t r e r 6 E z n y z m y e m s
Chapter 6 Enzymes 4. Examples of enzymatic reactions acid-base catalysis: give and take protons covalent catalysis: a transient covalent bond is formed between the enzyme and the substrate metal ion catalysis:
More informationEnzymes I. Dr. Mamoun Ahram Summer semester,
Enzymes I Dr. Mamoun Ahram Summer semester, 2017-2018 Resources Mark's Basic Medical Biochemistry Other resources NCBI Bookshelf: http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=books The Medical Biochemistry
More informationEnzymes Enzyme Mechanism
Mechanisms of Enzymes BCMB 3100 Chapters 6, 7, 8 Enzymes Enzyme Mechanism 1 Energy diagrams Binding modes of enzyme catalysis Chemical modes of enzyme catalysis Acid-Base catalysis Covalent catalysis Binding
More informationEnzymes Enzyme Mechanism
BCMB 3100 Chapters 6, 7, 8 Enzymes Enzyme Mechanism 1 Mechanisms of Enzymes Energy diagrams Binding modes of enzyme catalysis Chemical modes of enzyme catalysis Acid-Base catalysis Covalent catalysis Binding
More information2. Which of the following are nucleophiles and which are electrophiles?
Life Sciences 1a ractice roblems 7 1. a) ow many intermediates are there in the reaction? b) ow many transition states are there? c) What is the fastest step in the reaction? d) Which is more stable, A
More informationPyruvate is reduced to lactate in anaerobic metabolism in muscle cells
Pyruvate is reduced to lactate in anaerobic metabolism in muscle cells Transferases and hydrolases catalyze group transfer reactions Acyl transfer: Hexokinase catalyzes a phosphoryl transfer from ATP to
More informationEnzyme function: the transition state. Enzymes & Kinetics V: Mechanisms. Catalytic Reactions. Margaret A. Daugherty A B. Lecture 16: Fall 2003
Lecture 16: Enzymes & Kinetics V: Mechanisms Margaret A. Daugherty Fall 2003 Enzyme function: the transition state Catalytic Reactions A B Catalysts (e.g. enzymes) act by lowering the transition state
More informationCatalytic Reactions. Intermediate State in Catalysis. Lecture 16: Catalyzed reaction. Uncatalyzed reaction. Enzymes & Kinetics V: Mechanisms
Enzyme function: the transition state Catalytic Reactions Lecture 16: Enzymes & Kinetics V: Mechanisms Margaret A. Daugherty Fall 2003 A B Catalysts (e.g. enzymes) act by lowering the transition state
More informationWhat is an enzyme? Lecture 12: Enzymes & Kinetics I Introduction to Enzymes and Kinetics. Margaret A. Daugherty Fall General Properties
Lecture 12: Enzymes & Kinetics I Introduction to Enzymes and Kinetics Margaret A. Daugherty Fall 2003 ENZYMES: Why, what, when, where, how? All but the who! What: proteins that exert kinetic control over
More informationChemistry Problem Set #9 Due on Thursday 11/15/18 in class.
Chemistry 391 - Problem Set #9 Due on Thursday 11/15/18 in class. Name 1. There is a real enzyme called cocaine esterase that is produced in bacteria that live at the base of the coca plant. The enzyme
More information10/26/2010. An Example of a Polar Reaction: Addition of H 2 O to Ethylene. to Ethylene
6.5 An Example of a Polar Reaction: Addition of H 2 O to Ethylene Addition of water to ethylene Typical polar process Acid catalyzed addition reaction (Electophilic addition reaction) Polar Reaction All
More information2013 W. H. Freeman and Company. 6 Enzymes
2013 W. H. Freeman and Company 6 Enzymes CHAPTER 6 Enzymes Key topics about enzyme function: Physiological significance of enzymes Origin of catalytic power of enzymes Chemical mechanisms of catalysis
More informationPrinciples of Enzyme Catalysis Arthur L. Haas, Ph.D. Department of Biochemistry and Molecular Biology
Principles of Enzyme Catalysis Arthur L. Haas, Ph.D. Department of Biochemistry and Molecular Biology Review: Garrett and Grisham, Enzyme Specificity and Regulation (Chapt. 13) and Mechanisms of Enzyme
More informationG. GENERAL ACID-BASE CATALYSIS
G. GENERAL ACID-BASE CATALYSIS Towards a Better Chemical Mechanism via Catalysis There are two types of mechanisms we ll be discussing this semester. Kinetic mechanisms are concerned with rate constants
More informationBiochemistry 462a - Enzyme Kinetics Reading - Chapter 8 Practice problems - Chapter 8: (not yet assigned); Enzymes extra problems
Biochemistry 462a - Enzyme Kinetics Reading - Chapter 8 Practice problems - Chapter 8: (not yet assigned); Enzymes extra problems Introduction Enzymes are Biological Catalysis A catalyst is a substance
More informationMITOCW watch?v=gboyppj9ok4
MITOCW watch?v=gboyppj9ok4 The following content is provided under a Creative Commons license. Your support will help MIT OpenCourseWare continue to offer high quality educational resources for free. To
More informationWhat is an enzyme? Lecture 12: Enzymes & Kinetics I Introduction to Enzymes and Kinetics. Margaret A. Daugherty Fall 2004 KEY FEATURES OF ENZYMES
Lecture 12: Enzymes & Kinetics I Introduction to Enzymes and Kinetics Margaret A. Daugherty Fall 2004 What is an enzyme? General Properties Mostly proteins, but some are actually RNAs Biological catalysts
More informationCourse Goals for CHEM 202
Course Goals for CHEM 202 Students will use their understanding of chemical bonding and energetics to predict and explain changes in enthalpy, entropy, and free energy for a variety of processes and reactions.
More informationBiologic catalysts 1. Shared properties with chemical catalysts a. Enzymes are neither consumed nor produced during the course of a reaction. b.
Enzyme definition Enzymes are protein catalysts that increase the velocity of a chemical reaction and are not consumed during the reaction they catalyze. [Note: Some types of RNA can act like enzymes,
More informationBMB Lecture Covalent Catalysis 2. General Acid-base catalysis
BMB 178 2017 Lecture 3 1. Covalent Catalysis 2. General Acid-base catalysis Evidences for A Covalent Intermediate Direct Evidences: Direct observation of formation and disappearance of an intermediate
More informationChemistry 5.07SC Biological Chemistry I Fall Semester, 2013
Chemistry 5.07SC Biological Chemistry I Fall Semester, 2013 Lecture 9 Biochemical Transformations I. Carbon-carbon bond forming and cleaving reactions in Biology (see the Lexicon). Enzymes catalyze a limited
More informationChapter 25: The Chemistry of Life: Organic and Biological Chemistry
Chemistry: The Central Science Chapter 25: The Chemistry of Life: Organic and Biological Chemistry The study of carbon compounds constitutes a separate branch of chemistry known as organic chemistry The
More informationEnzymes and Protein Structure
Enzymes and Protein Structure Last Week PTM s We (Re)Learned About Primary Structure And Tertiary Structure S-Q-D-A-G-M-Q-Q-G-A-D-M-D-Q-V-S-A Secondary Structure Enzymes What are these crazy things called
More informationC a h p a t p e t r e r 6 E z n y z m y e m s
Chapter 6 Enzymes 1. An Introduction to Enzymes Enzymes are catalytically active biological macromolecules Enzymes are catalysts of biological systems Almost every biochemical reaction is catalyzed by
More informationLec.1 Chemistry Of Water
Lec.1 Chemistry Of Water Biochemistry & Medicine Biochemistry can be defined as the science concerned with the chemical basis of life. Biochemistry can be described as the science concerned with the chemical
More informationNucleophilic Addition Reactions of Carboxylic Acid Derivatives
Lecture 5: bjectives: Nucleophilic Addition eactions of Carboxylic Acid Derivatives By the end of this lecture you will be able to: draw the mechanism of a nucleophilic addition-elimination reaction with
More informationLecture 14 (10/18/17) Lecture 14 (10/18/17)
Lecture 14 (10/18/17) Reading: Ch6; 190-191, 194-195, 197-198 Problems: Ch6 (text); 7, 24 Ch6 (study guide-facts); 4, 13 NEXT Reading: Ch6; 198-203 Ch6; Box 6-1 Problems: Ch6 (text); 8, 9, 10, 11, 12,
More informationMechanisms of catalysis
Mechanisms of catalysis Proximity and orientation effects Proximity: Reaction between bound molecules doesn't require an improbable collision of 2 molecules -- they're already in "contact" (increases the
More informationBio-elements. Living organisms requires only 27 of the 90 common chemical elements found in the crust of the earth, to be as its essential components.
Bio-elements Living organisms requires only 27 of the 90 common chemical elements found in the crust of the earth, to be as its essential components. Most of the chemical components of living organisms
More informationEnzymes and Enzyme Kinetics I. Dr. Kevin Ahern
Enzymes and Enzyme Kinetics I Dr. Kevin Ahern Enzymatic Reactions Enzymatic Reactions Enzymatically Catalyzed Reactions Background Substrates Bound at Active Site of the Methylene Tetrahydrofolate Reductase
More informationChapter 20 Carboxylic Acid Derivatives Nucleophilic Acyl Substitution
Chapter 20 Carboxylic Acid Derivatives Nucleophilic Acyl Substitution Nomenclature: In carboxylic acid chlorides, anhydrides, esters and amides, the parent is the carboxylic acid. In each case be sure
More informationEnergy, Enzymes, and Metabolism. Energy, Enzymes, and Metabolism. A. Energy and Energy Conversions. A. Energy and Energy Conversions
Energy, Enzymes, and Metabolism Lecture Series 6 Energy, Enzymes, and Metabolism B. ATP: Transferring Energy in Cells D. Molecular Structure Determines Enzyme Fxn Energy is the capacity to do work (cause
More informationBMB Lecture 2
BMB 178 2018 Lecture 2 How to map transition state Covalent Catalysis How to Map Transition States 1. Linear Free Energy Relationship 2. Kinetic Isotope Effects 3. Transition state analogues Linear Free
More information1/4/2011. Chapter 18 Aldehydes and Ketones Reaction at the -carbon of carbonyl compounds
Chapter 18 Aldehydes and Ketones Reaction at the -carbon of carbonyl compounds The Acidity of the Hydrogens of Carbonyl Compounds: Enolate Anions Hydrogens on carbons to carbonyls are unusually acidic
More informationChapter 8 Metabolism: Energy, Enzymes, and Regulation
Chapter 8 Metabolism: Energy, Enzymes, and Regulation Energy: Capacity to do work or cause a particular change. Thus, all physical and chemical processes are the result of the application or movement of
More informationBasic Concepts of Enzyme Action. Enzymes. Rate Enhancement 9/17/2015. Stryer Short Course Chapter 6
Basic Concepts of Enzyme Action Stryer Short Course Chapter 6 Enzymes Biocatalysts Active site Substrate and product Catalyzed rate Uncatalyzed rate Rate Enhancement Which is a better catalyst, carbonic
More information21.1 Introduction Carboxylic Acids Nomenclature of Carboxylic Acids. Acids Structure and Properties of Carboxylic Acids.
21.1 Introduction Carboxylic Acids Carboxylic acids are abundant in nature and in pharmaceuticals. 21.1 Introduction Carboxylic Acids The US produces over 2.5 million tons of acetic acid per year, which
More informationSynthesis of Nitriles a. dehydration of 1 amides using POCl 3 : b. SN2 reaction of cyanide ion on halides:
I. Nitriles Nitriles consist of the CN functional group, and are linear with sp hybridization on C and N. Nitriles are non-basic at nitrogen, since the lone pair exists in an sp orbital (50% s character
More information[Urea] (M) k (s -1 )
BMB178 Fall 2018 Problem Set 1 Due: 10/26/2018, noon Office hour: 10/25/2018, SFL GSR218 7 9 pm Problem 1. Transition state theory (20 points): Consider a unimolecular reaction where a substrate S is converted
More informationTwo requirements for life: Self-replication and appropriate catalysis. A. Most enzymes (def.: biological catalysts) are proteins
Enzymes We must be able to enhance the rates of many physical and chemical processes to remain alive and healthy. Support for that assertion: Maladies of genetic origin. Examples: Sickle-cell anemia (physical)
More informationReversible Additions to carbonyls: Weak Nucleophiles Relative Reactivity of carbonyls: Hydration of Ketones and Aldehydes
Reversible Additions to carbonyls: Weak Nucleophiles Weak nucleophiles, such as water, alcohols, and amines, require acid or base catalysis to undergo addition to carbonyl compounds Relative Reactivity
More information[Urea] (M) k (s -1 )
BMB178 Fall 2018 Problem Set 1 Due: 10/26/2018, noon Office hour: 10/25/2018, SFL GSR218 7 9 pm Problem 1. Transition state theory (20 points): Consider a unimolecular reaction where a substrate S is converted
More informationFinal Chem 4511/6501 Spring 2011 May 5, 2011 b Name
Key 1) [10 points] In RNA, G commonly forms a wobble pair with U. a) Draw a G-U wobble base pair, include riboses and 5 phosphates. b) Label the major groove and the minor groove. c) Label the atoms of
More informationChapter 8. Enzymes: basic concept and kinetics
Chapter 8 Enzymes: basic concept and kinetics Learning objectives: mechanism of enzymatic catalysis Michaelis -Menton Model Inhibition Single Molecule of Enzymatic Reaction Enzymes: catalysis chemical
More informationCatalytic power of enzymes
Enzyme catalysis Catalytic power of enzymes Enzymatic reactions are involved in most biological processes. There is a major practical and fundamental interest in finding out what makes enzymes so efficient
More informationChapter 19 Substitutions at the Carbonyl Group
Chapter 19 Substitutions at the Carbonyl Group In Chapter 18 Additions to the Carbonyl Groups In Chapter 19 Substitutions at the Carbonyl Group O O - - O - O R Y R C+ Y R Y Nu -Ȳ R N u + Y=goodleavinggroup
More informationENZYME SCIENCE AND ENGINEERING PROF. SUBHASH CHAND DEPARTMENT OF BIOCHEMICAL ENGINEERING AND BIOTECHNOLOGY IIT DELHI LECTURE 3
ENZYME SCIENCE AND ENGINEERING PROF. SUBHASH CHAND DEPARTMENT OF BIOCHEMICAL ENGINEERING AND BIOTECHNOLOGY IIT DELHI LECTURE 3 ENZYMES AS BIOCATALYSTS * CATALYTIC EFFICIENCY *SPECIFICITY Having discussed
More informationObjectives INTRODUCTION TO METABOLISM. Metabolism. Catabolic Pathways. Anabolic Pathways 3/6/2011. How to Read a Chemical Equation
Objectives INTRODUCTION TO METABOLISM. Chapter 8 Metabolism, Energy, and Life Explain the role of catabolic and anabolic pathways in cell metabolism Distinguish between kinetic and potential energy Distinguish
More informationChapter 9 Aldehydes and Ketones
Chapter 9 Aldehydes and Ketones 9.1 Nomenclature of Aldehydes and Ketones Aldehydes are named by replacing the -e of the corresponding parent alkane with -al The aldehyde functional group is always carbon
More informationEnzymes and Enzyme Kinetics I. Dr.Nabil Bashir
Enzymes and Enzyme Kinetics I Dr.Nabil Bashir Enzymes and Enzyme Kinetics I: Outlines Enzymes - Basic Concepts and Kinetics Enzymes as Catalysts Enzyme rate enhancement / Enzyme specificity Enzyme cofactors
More informationBIOLOGICAL SCIENCE. Lecture Presentation by Cindy S. Malone, PhD, California State University Northridge. FIFTH EDITION Freeman Quillin Allison
BIOLOGICAL SCIENCE FIFTH EDITION Freeman Quillin Allison 8 Lecture Presentation by Cindy S. Malone, PhD, California State University Northridge Roadmap 8 In this chapter you will learn how Enzymes use
More informationExam 4 April 15, 2005 CHEM 3511 Print Name: KEY Signature
1) (8 pts) General Properties of Enzymes. Give four properties of enzymaticallycatalyzed reactions. The answers should indicate how enzymatic reactions differ from non-enzymatic reactions. Write four only
More informationCarboxylic Acids and Nitriles
Carboxylic Acids and Nitriles Why this Chapter? Carboxylic acids present in many industrial processes and most biological processes They are the starting materials from which other acyl derivatives are
More informationChapter 6 Overview. Enzymes. Catalysis most important function of proteins. Globular protein Increase rate of metabolic processes
Chapter 6 Overview Enzymes Catalysis most important function of proteins n Enzymes protein catalysts Globular protein Increase rate of metabolic processes Enzymes kinetics info on reaction rates & measure
More informationStudy Guide: Basic Chemistry, Water, Life Compounds and Enzymes
Study Guide: Basic Chemistry, Water, Life Compounds and Enzymes 1. Lipids are good energy-storage molecules because a) the can absorb a large amount of energy while maintaining a constant temperature b)
More informationNAME. EXAM I I. / 36 September 25, 2000 Biochemistry I II. / 26 BICH421/621 III. / 38 TOTAL /100
EXAM I I. / 6 September 25, 2000 Biochemistry I II. / 26 BIH421/621 III. / 8 TOTAL /100 I. MULTIPLE HOIE (6 points) hoose the BEST answer to the question by circling the appropriate letter. 1. An amino
More information2/28/2011. Chapter 6 An Overview of Organic Reactions. Organic Chemical Reactions. 6.1 Kinds of Organic Reactions
John E. McMurry http://www.cengage.com/chemistry/mcmurry Chapter 6 An Overview of Organic Reactions CHP 6 Problems: 6.1-13, 17-36. Richard Morrison University of Georgia, Athens Organic Chemical Reactions
More informationChapter 8: An Introduction to Metabolism
Chapter 8: An Introduction to Metabolism Key Concepts 8.1 An organism s metabolism transforms matter and energy, subject to the laws of thermodynamics 8.2 The free-energy change of a reaction tells us
More informationKey ideas: In EAS, pi bond is Nu and undergoes addition.
Objective 7. Apply addition and elimination concepts to predict electrophilic aromatic substitution reactions (EAS) of benzene and monosubstituted benzenes. Skills: Draw structure ID structural features
More informationAn Introduction to Metabolism. Chapter 8
An Introduction to Metabolism Chapter 8 METABOLISM I. Introduction All of an organism s chemical reactions Thousands of reactions in a cell Example: digest starch use sugar for energy and to build new
More informationChapter 19. Synthesis and Reactions of b-dicarbonyl Compounds: More Chemistry of Enolate Anions. ß-dicarbonyl compounds. Why are ß-dicarbonyls useful?
Chapter 19 Synthesis and Reactions of b-dicarbonyl Compounds: More Chemistry of Enolate Anions ß-dicarbonyl compounds Two carbonyl groups separated by a carbon Three common types ß-diketone ß-ketoester
More information9/25/2011. Outline. Overview: The Energy of Life. I. Forms of Energy II. Laws of Thermodynamics III. Energy and metabolism IV. ATP V.
Chapter 8 Introduction to Metabolism Outline I. Forms of Energy II. Laws of Thermodynamics III. Energy and metabolism IV. ATP V. Enzymes Overview: The Energy of Life Figure 8.1 The living cell is a miniature
More informationEnzyme Catalysis & Biotechnology
L28-1 Enzyme Catalysis & Biotechnology Bovine Pancreatic RNase A Biochemistry, Life, and all that L28-2 A brief word about biochemistry traditionally, chemical engineers used organic and inorganic chemistry
More informationChapters 5-6 Enzymes. Catalyst: A substance that speeds up the rate of a chemical reaction but is not itself consumed.
hapters 56 Enzymes atalyst: A substance that speeds up the rate of a chemical reaction but is not itself consumed. Most biological catalysts are proteins but some RA are catalysts too. e.g. Peptide bonds
More informationMembrane Proteins: 1. Integral proteins: 2. Peripheral proteins: 3. Amphitropic proteins:
Membrane Proteins: 1. Integral proteins: proteins that insert into/span the membrane bilayer; or covalently linked to membrane lipids. (Interact with the hydrophobic part of the membrane) 2. Peripheral
More informationIf you like us, please share us on social media. The latest UCD Hyperlibrary newsletter is now complete, check it out.
Sign In Forgot Password Register username username password password Sign In If you like us, please share us on social media. The latest UCD Hyperlibrary newsletter is now complete, check it out. ChemWiki
More informationBiochemistry Enzyme kinetics
1 Description of Module Subject Name Paper Name Module Name/Title Enzyme Kinetics Dr. Vijaya Khader Dr. MC Varadaraj 2 1. Objectives 2. Enzymes as biological catalyst 3. Enzyme Catalysis 4. Understanding
More informationCHAPTER 8. An Introduction to Metabolism
CHAPTER 8 An Introduction to Metabolism WHAT YOU NEED TO KNOW: Examples of endergonic and exergonic reactions. The key role of ATP in energy coupling. That enzymes work by lowering the energy of activation.
More informationChapter 9 Aldehydes and Ketones Excluded Sections:
Chapter 9 Aldehydes and Ketones Excluded Sections: 9.14-9.19 Aldehydes and ketones are found in many fragrant odors of many fruits, fine perfumes, hormones etc. some examples are listed below. Aldehydes
More informationBiomolecules: lecture 9
Biomolecules: lecture 9 - understanding further why amino acids are the building block for proteins - understanding the chemical properties amino acids bring to proteins - realizing that many proteins
More informationCHEM 251 (4 credits): Description
CHEM 251 (4 credits): Intermediate Reactions of Nucleophiles and Electrophiles (Reactivity 2) Description: An understanding of chemical reactivity, initiated in Reactivity 1, is further developed based
More informationEnzyme reactions mechanisms and Immobilization of enzymes
Enzyme reactions mechanisms and Immobilization of enzymes Lecture 18.11.2016 CHEM-E3140 Bioprocess Technology II Aalto University School of Chemical Technology Ossi Turunen 1 Reaction mechanisms 1) General
More informationAdditions to the Carbonyl Groups
Chapter 18 Additions to the Carbonyl Groups Nucleophilic substitution (S N 2andS N 1) reaction occurs at sp3 hybridized carbons with electronegative leaving groups Why? The carbon is electrophilic! Addition
More informationLecture 16 (10/23/17) Lecture 16 (10/23/17)
Lecture 16 (10/23/17) Reading: Ch6; 207-210 Ch6; 192-193, 195-196, 205-206 Problems: Ch6 (text); 18, 19, 20, 21, 22 Ch6 (study guide-facts); 9, 11 Ch6 (study guide-applying); 2 NEXT Reading: Ch6; 213-218
More informationAn Introduction to Metabolism
Chapter 8 An Introduction to Metabolism Edited by Shawn Lester PowerPoint Lecture Presentations for Biology Eighth Edition Neil Campbell and Jane Reece Lectures by Chris Romero, updated by Erin Barley
More informationChapter 19 Carboxylic Acids
Carboxylic acids have the formula RCO2H. Nomenclature Chapter 19 Carboxylic Acids For the parent alkane, drop the terminal e and add the suffix oic acid. The parent alkane is the longest continuous chain
More informationMolecular Geometry: VSEPR model stand for valence-shell electron-pair repulsion and predicts the 3D shape of molecules that are formed in bonding.
Molecular Geometry: VSEPR model stand for valence-shell electron-pair repulsion and predicts the 3D shape of molecules that are formed in bonding. Sigma and Pi Bonds: All single bonds are sigma(σ), that
More informationChapter 17. Carbonyl Compounds I Nucleophilic Acyl Substitution
Chapter 17. Carbonyl Compounds I Nucleophilic Acyl Substitution Carbonyl compounds: compounds containing C=O group. 1. Class I carbonyl compounds: Carboxylic acids and derivatives containing a group (
More informationp Bonds as Electrophiles
Chapter 7 p Bonds as Electrophiles REACTIONS OF CARBONYLS AND RELATED FUNCTIONAL GROUPS Copyright 2018 by Nelson Education Limited 1 7.2.1 Orbital structure of the carbonyl group Because oxygen is more
More informationSubstitution and Elimination reactions
PART 3 Substitution and Elimination reactions Chapter 8. Substitution reactions of RX 9. Elimination reactions of RX 10. Substit n/elimin n of other comp ds 11. Organometallic comp ds 12. Radical reactions
More informationChapter 6- An Introduction to Metabolism*
Chapter 6- An Introduction to Metabolism* *Lecture notes are to be used as a study guide only and do not represent the comprehensive information you will need to know for the exams. The Energy of Life
More informationChem 204. Mid-Term Exam I. July 21, There are 3 sections to this exam: Answer ALL questions
Chem 204 Mid-Term Exam I July 21, 2009 Name: Answer Key Student ID: There are 3 sections to this exam: Answer ALL questions Section I: Multiple-Choice 20 questions, 2 pts each Section II: Fill-in-the-Blank
More informationBIOLOGY 101. CHAPTER 4: Carbon and the Molecular Diversity of Life: Carbon: the Backbone of Life
BIOLOGY 101 CHAPTER 4: Carbon and the Molecular Diversity of Life: CONCEPTS: 4.1 Organic chemistry is the study of carbon compounds 4.2 Carbon atoms can form diverse molecules by bonding to four other
More informationChapter 19. Carbonyl Compounds III Reaction at the α-carbon
Chapter 19. Carbonyl Compounds III Reaction at the α-carbon There is a basic hydrogen (α hydrogen) on α carbon, which can be removed by a strong base. 19.1 The Acidity of α-hydrogens A hydrogen bonded
More informationChapter 10: Carboxylic Acids and Their Derivatives
Chapter 10: Carboxylic Acids and Their Derivatives The back of the white willow tree (Salix alba) is a source of salicylic acid which is used to make aspirin (acetylsalicylic acid) The functional group
More informationCourtesy of Elsevier. Used with permission.
Chemistry 5.07 2013 Problem Set 5 Answers Problem 1 Succinate dehydrogenase (SDH) is a heterotetramer enzyme complex that catalyzes the oxidation of succinate to fumarate with concomitant reduction of
More informationLecture 3: Aldehydes and ketones
Lecture 3: Aldehydes and ketones I want to start by talking about the mechanism of hydroboration/ oxidation, which is a way to get alcohols from alkenes. This gives the anti-markovnikov product, primarily
More informationCHEM 3653 Exam # 1 (03/07/13)
1. Using phylogeny all living organisms can be divided into the following domains: A. Bacteria, Eukarya, and Vertebrate B. Archaea and Eukarya C. Bacteria, Eukarya, and Archaea D. Eukarya and Bacteria
More informationCHAPTER 29 HW: AMINO ACIDS + PROTEINS
CAPTER 29 W: AMI ACIDS + PRTEIS For all problems, consult the table of 20 Amino Acids provided in lecture if an amino acid structure is needed; these will be given on exams. Use natural amino acids (L)
More informationChemistry 5.07SC Biological Chemistry I Fall Semester, 2013
Chemistry 5.07SC Biological Chemistry I Fall Semester, 2013 Lecture 10. Biochemical Transformations II. Phosphoryl transfer and the kinetics and thermodynamics of energy currency in the cell: ATP and GTP.
More informationBSc and MSc Degree Examinations
Examination Candidate Number: Desk Number: BSc and MSc Degree Examinations 2018-9 Department : BIOLOGY Title of Exam: Molecular Biology and Biochemistry Part I Time Allowed: 1 hour and 30 minutes Marking
More informationProton Acidity. (b) For the following reaction, draw the arrowhead properly to indicate the position of the equilibrium: HA + K + B -
Proton Acidity A01 Given that acid A has a pk a of 15 and acid B has a pk a of 10, then: (a) Which of the two acids is stronger? (b) For the following reaction, draw the arrowhead properly to indicate
More informationPETER PAZMANY CATHOLIC UNIVERSITY Consortium members SEMMELWEIS UNIVERSITY, DIALOG CAMPUS PUBLISHER
PETER PAZMANY SEMMELWEIS CATHOLIC UNIVERSITY UNIVERSITY Development of Complex Curricula for Molecular Bionics and Infobionics Programs within a consortial* framework** Consortium leader PETER PAZMANY
More information