Abstact

The 3D structure of bovine recombinant acyl-coenzyme A binding protein has been determined using multidimensional heteronuclear magnetic resonance spectroscopy in a study that combines investigations of 15N-labeled and unlabeled protein. The present structure determination is a refinement of the structure previously determined (Andersen, K.V. and Poulsen, F.M. (1992) J. Mol. Biol., 226, 1131-1141). It is based on 1096 distance restraints and 124 dihedral angle restraints of which 69 are for phi-angles and 8 for chiral centers and 47 for prochiral centers. The new experimental input for the structure determination has provided an increase of 263 distance restraints, 5 phi-angle restraints, and 32 chi-angle restraints in 2 chiral centers, and 31 prochiral centers restraining an additional 23 chi 1, 8 chi 2, and 1 chi 3 angles. The increase of 300 distance and dihedral angle restraints representing an additional 30% of input parameters for the structure determination has been shown to be in agreement with the first structure. A set of 29 structures has been calculated and each of the structures has been compared to a mean structure to give an atomic root mean square deviation of 0.44 +/- 0.12 A (1 A is 0.1 nm) for the backbone atoms C, C alpha, and N in the four alpha-helices A1, residues 4-15, A2, residues 21-36, A3, residues 51-62 and A4, residues 65-84. The loop-region of residues Gly45-Lys50 could not be defined by the restraints obtained by NMR. The program PRONTO has been used for the spectrum analysis, assignment of the individual nuclear Overhauser effects, the integration of the cross peaks, and the measurement of the coupling constants. The programs DIANA, X-PLOR and INSIGHT have been used in the structure calculations and evaluations.