ISSN:
1573-5001
Keywords:
χ1-angle
;
flavodoxin
;
multiple-quantum line-narrowing
;
multiplet simulation
;
ribonuclease T1
;
vicinal coupling constants
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
Notes:
Abstract Constant-time 3D heteronuclear relayed E.COSY [Schmidt et al. (1996) J. Biomol. NMR, 7, 142–152], as based on generic 2D small-flip-angle HMQC-COSY [Schmidt et al. (1995) J. Biomol. NMR, 6, 95–105], has been modified to allow for quantitative determination of heteronuclear three-bond 3 J(Hα,Cγ) couplings. The method is applicable to amino acid spin topologies with carbons in the γ position which lack attached protons, i.e. to asparagine, aspartate, and aromatic residues in uniformly 13C-enriched proteins. The pulse sequence critically exploits heteronuclear triple-quantum coherence (HTQC) of CH2 moieties involving geminal Hβ proton pairs, taking advantage of improved multiple-quantum relaxation properties, at the same time avoiding scalar couplings between those spins involved in multiple-quantum coherence, thus yielding E.COSY-type multiplets with a splitting structure that is simpler than with the original scheme. Numerical least-squares 2D line-shape simulation is used to extract 3 J(Hα,Cγ) coupling constants which are of relevance to side-chain χ1 dihedral-angle conformations in polypeptides. Methods are demonstrated with recombinant 15N,13C-enriched ribonuclease T1 and Desulfovibrio vulgaris flavodoxin with bound oxidized FMN.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1008385202639
