Biosynthesis of vitamin B12: stereochemistry of transfer of a hydride equivalent from NADPH by precorrin-6x reductase
摘要:
Deuterium labelling with NMR analysis demonstrates that the enzyme precorrin-6x reductase transfers HR from C-4 of the pyridine residue of NADPH as the first step in the sequence leading from precorrin-6x to hydrogenobyrinic acid.
Biosynthesis of vitamin B12: the structure of factor IV, the oxidized form of precorrin-4
摘要:
13
C Labelling and NMR experiments establish the structure of factor IV, the oxidized form of the tetramethylated intermediate on the biosynthetic pathway to precorrin-6x 2 in Pseudomonas denitrificans, thus demonstrating that the contraction of the macrocycle leads to an acetyl derivative at C-1.