Stereospecific ¹H and ¹³C NMR assignments of crotonyl CoA and hexadienoyl CoA: Conformational analysis and comparison with protein-CoA complexes

Stereospecific ¹H and ¹³C resonance assignments of hexadienoyl-CoA and crotonyl-CoA have been determined. The two diastereotopic methyl groups at the C2' carbon were assigned via transferred nuclear Overhauser effect experiments on the complex of hexadienoyl-CoA with the enzyme enoyl-CoA hydratase. The two diastereotopic 1' protons were assigned using heteronuclear multiple-bond correlation experiments in conjunction with rotating frame nuclear Overhauser spectroscopy. This represents the first set of complete stereospecific assignments for any CoA derivative. The assignments allow a detailed quantitative conformational analysis of the uncomplexed form of the molecule. In particular, the relative population of the various rotamers about the C1'-C2' and the C2'-C3' bonds have been determined. The database of protein-bound CoA structures has been surveyed and used to compare the structure(s) of CoA in protein-CoA complexes with the conformational preferences of free CoA.