NMR ~(h3)J_(NC') Couplings Provide Comprehensive Geometrical Constraints for Protein H-bonds in Solution

摘要

Protein backbone H-bonds ( > N-H···O-C < ) show relationships between NMR ~(h3)J_(NC') couplings measured in solution and H-bond geometry parameters seen in X-ray crystal structures. Assuming that the solution and crystal structure of protein backbone is the same, the ~(h3)J_(NC') couplings can be calibrated to provide good estimates of both angular and radial H-bond parameters in a solution. The crucial premise of equality between the solution and the crystal structure of protein backbone we validated on the level of the NH-bonds orientation, by comparing the orientations inferred from X-ray crystal structures with the solution ones determined from NMR residual dipolar couplings.%Prikazana je korelacija između ~(h3)J_(NC'') NMR sprega izmjerenih u otopini i geometrijskih parametara vodikovih veza ( > N-H···O-C < ) glavnog proteinskog lanca u kristalnoj strukturi. Uz pretpostavku da su geometrije proteinskih lanaca u otopini jednake onima u kristalnim strukturama, moguće je kalibrirati ~(h3)J_(NC'') sprege za procjenu kutova i duljina vodikovih veza u otopinama. Bitna pretpostavka o očuvanju geometrije proteinskog lanca iz kristalne strukture u otopini potvrđena je usporedbom orijentacija N-H veza iz kristalne strukture s onima u otopini, određenima iz rezidualnih dipolarnih NMR sprega.