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Determination of ψ Torsion Angle Restraints from 3J(Cα,Cα) and 3J(Cα,HN) Coupling Constants in Proteins
journal contribution
posted on 2000-06-14, 00:00 authored by Mirko Hennig, Wolfgang Bermel, Harald Schwalbe, Christian GriesingerHomonuclear 3J(Cα,Cα) and heteronuclear 3J(Cα,HN) coupling constants have been determined in
the protein ubiquitin. Despite the fact that all amide bonds in ubiquitin have a trans conformation, considerable
spread in the size of the coupling constants can be observed. The 3J(Cα,HN) coupling constants vary from 0.0
to 1.0 Hz, and the 3J(Cα,Cα) coupling constants that could be determined vary from 1.1 to 2.2 Hz. Interpretation
of the coupling constants reveals a non-Karplus-type dependence and suggests that vicinal homonuclear 3J(Cα,Cα)
and heteronuclear 3J(Cα,HN) depend on the ψi-1 torsion angle. The proposed sensitive E.COSY-type HNCO[Cα]
experiment for the measurement of vicinal 3J(Cα,HN) coupling constants can be used in protonated and deuterated
proteins, and the quantitative J correlation experiment HN(COCA)CA can be carried out on perdeuterated
proteins for the measurement of 3J(Cα,Cα) that provide unique torsion angle information in these proton sparse
proteins.