NOEY and ROEY type experiments explorin internuclear distances Assistant Professor Kenneth Konstad Bioanalytical Chemistry and Metabolomics Research Group ection for Natural Products and Peptides Department of Dru Desin and Pharmacoloy Faculty of Health and Medical ciences University of Copenhaen Phone: +45 3533 6411; Fax: +45 3533 6041 E-mail: kenneth.konstad@sund.ku.dk Bioanalytical Chemistry and Metabolomics Research Group
Department of Dru Desin and Pharmacoloy Lecture outline ü Nuclear Overhauser Effect (a.k.a. the NOE) ü 1D NOE experiments ü D NOE experiments Dias
Dias 3 Department of Dru Desin and Pharmacoloy Relaxation in a two-spin system Two-spin system with the followin characteristics and definitions: ü Nuclei ( saturated ) ü Nuclei ( insensitive/interestin ) ü Not necessarily J-coupled but miht be ü Two spectral lines ü Close enouh to interact via dipole-dipole interaction (= T 1 relaxation) R 1 r -6 (DD) = = n 1 CH! CH T 1(DD) t c
Dias 4 Department of Dru Desin and Pharmacoloy ntroducin the enery diaram (two spin system)
Department of Dru Desin and Pharmacoloy Relaxation in a two-spin system enery diaram bb ba W 0 W ab aa Dias 5 inle-, zero- and double-quantum transitions ü NOE: Peak intensity of one nucleus chanes when equilibrium population of states of another nucleus is chaned (by saturation, inversion pulse) ü Necessity: The nuclei are close in space = able to undero T 1 relaxation ( dipole-dipole coupled spins ) ü NOE is due to W 0 and W processes (cross-relaxation between dipole-dipole coupled spins)
ú û ù ê ë é + µ ) (1 3 6 1 c c r W w t t [ ] ú ú û ù ê ê ë é + µ 6 0 ) ( 1 c c r W t w w t [ ] ú ú û ù ê ê ë é + + µ 6 ) ( 1 1 c c r W t w w t ú û ù ê ë é µ 6 1 3 r W c t ú û ù ê ë é µ 6 0 r W c t ú ú û ù ê ê ë é µ 6 1 r W c t 3 1 Transition probabilities (relaxation rates) Dias 6 Department of Dru Desin and Pharmacoloy
Department of Dru Desin and Pharmacoloy teady state NOE bb ba W 0 W ab W 0 W aa rapidly saturated (situation immediately after saturation) W Dias 7 W 0 relaxation via W (rapidly tumblin molecules) saturated (situation after relaxation has occurred: THE NTENTY OF NCREAED!)
Dias 8 Department of Dru Desin and Pharmacoloy bb Maximum homonuclear NOE effect mall molecules Rapid tumblin ba W W 0 aa ab Macromolecules low tumblin
Department of Dru Desin and Pharmacoloy 1D NOE experiment teady-state (equilibrium) NOE: ü Lon saturation period ü Applicable to small molecules ü Positive NOE ü Difficult to use for determination of (relative) intramolecular distances because it is a result of complex kinetics involvin many neihborin spins. elective saturation Dias 9
Department of Dru Desin and Pharmacoloy 1D NOE experiments Transient NOE: ü elective inversion (with transient = RF pulse) rather than saturation ü Build-up curves can be constructed with increasin t m - thereby allowin measurin internuclear distances t m t 1 180 90 Dias 10
Department of Dru Desin and Pharmacoloy D transient NOE experiment: NOEY t 1 t m t 90 90 90 preparation evolution mixin detection t 1 t Dias 11
Dias 1 Department of Dru Desin and Pharmacoloy D transient NOE experiment: NOEY FT(F) FT(F1) preparation evolution mixin detection t 1 t
Dias 13 Department of Dru Desin and Pharmacoloy D transient NOE experiment: NOEY A W BA B W 0 BA B A COY B A NOEY
Department of Dru Desin and Pharmacoloy D transient NOE experiment: NOEY ome experimental/practical considerations: ü t m of the order of T 1 ü Receiver ain: luckily the first increment ives the larest FD intensity ü Artefacts: Antiphase cross peaks ( COY-type cross peaks ) between coupled nuclei (maximized if second and third pulse 90 ) ü Cross peaks have the same sin as diaonal (slow tumblin) or opposite (rapid tumblin). ü Processin: p/ shifted sine bell or squared sine bell in both dimensions Dias 14
Dias 15 Department of Dru Desin and Pharmacoloy Maximum homonuclear NOE effect No NOE = no sinals in D NOEY for lare small-molecules
Dias 16 Department of Dru Desin and Pharmacoloy ROEY (= CAMELPN)
Department of Dru Desin and Pharmacoloy ROEY (= CAMELPN) ROEY: ü Rotatin frame Overhauser Effect pectroscopy CAMELPN: ü Cross-relaxation Appropriate for Mini-molecules EmuLated by PNlockin t 1 t m t p/ spin-lock y ROE cross-peaks neative, chemical exchane positive, complications due to TOCY transfers Dias 17
Department of Dru Desin and Pharmacoloy D NOEY spectrum OH H 3 C O O N H Dias 18 tandard NOEY experiment at 400 MHz; t m = 600 ms
Dias 19 Department of Dru Desin and Pharmacoloy D NOEY experiment cross peak intensity Lare molecules Biopharmaceuticals mall molecules Natural products
Department of Dru Desin and Pharmacoloy Other NOE experiments - HOEY Heteronuclear Overhauser Effect pectroscopy: ü Double resonance experiment ü nterestin for other nuclei than 13 C t 1 t m t t m 90 90 decouple 180 90 Refocusin pulse Dias 0
Department of Dru Desin and Pharmacoloy Other NOE experiments - HOEY Heteronuclear Overhauser Effect pectroscopy: ü Double resonance experiment ü nterestin for other nuclei than 13 C ü pecial probe miht be needed Li N N CH 3 THF-d 8, 0 C, 400 MHz Dias 1