M. Kumar et al., A METHYLNICKEL INTERMEDIATE IN A BIMETALLIC MECHANISM OF ACETYL-COENZYME-A SYNTHESIS BY ANAEROBIC-BACTERIA, Science, 270(5236), 1995, pp. 628-630
Resonance Raman (RR) spectroscopy was used to identify a methylnickel
adduct (nu(Ni-C) = 422 wave numbers) of carbon monoxide dehydrogenase
(CODH) from Clostridium thermoaceticum. Formed at a nickel/iron-sulfur
cluster on CODH called center A, the methylnickel species is the prec
ursor of the methyl group of acetyl-coenzyme A in an anaerobic pathway
of carbon monoxide or carbon dioxide fixation. Rapid kinetic and RR s
tudies demonstrated that methylation of nickel occurs by heterolysis o
f the methyl-cobalt bond (nu(Co-C) = 429 wave numbers) of a methylated
corrinoid/iron-sulfur protein. In combination with the earlier findin
g of an iron-carbonyl adduct at center A, defection of the methylnicke
l intermediate establishes a bimetallic mechanism for acetyl-coenzyme
A synthesis.