C-13 NMR AND H-1-H-1 NOES OF COENZYME-A - CONFORMATION OF THE PANTOICACID MOIETY

The 3''-hydroxyl group of the pantetheine moiety of coenzyme-A generat es diastereotopic methyl groups and protons at the 2''- and 1''-carbon s, respectively. An analysis of the available crystal structures of co enzyme-if complexed at enzyme active sites suggests a common conformat ion for the pantoic acid portion of pantetheine. In this conformation, the preferred conformations about the O(1'')-C1'' bond is anti, about the C1''-C2'' bond gauche, and about the C2''-C3'' anti, The reported H-1-H-1 nuclear Overhauser enhancements between these protons are con sistent with the observed crystal structure conformations and facilita te the assignments made to the diastereotopic resonances. A HeteroCOSY spectrum allowed an unequivocal and complete assignment of the C-13 N MR for coenzyme-A, resolving the discrepancies between the assignments made by Roeder et al. (Physiol. Chem. Phys. 7, 115-122 (1975)) and Pa tel and Walt (Anal. Biochem. 170, 355-360 (1988)). (C) 1995 Academic P ress, Inc.