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Anionic modulation of the catalytic activity of hydrogenase from Chlamydomonas reinhardtii

Journal Article · · Arch. Biochem. Biophys.; (United States)
Hydrogen production by cell-free extracts of Chlamydomonas reinhardtii is stimulated by anions when methyl viologen, reduced by dithionite, is used as the electron donor to hydrogenase. The increasing effectiveness of various anions closely follows their position in the Hofmeister chaotropic sequence. The most stimulatory anion tested, I/sup -/, gives a six-fold increase in activity at a concentration of 0.5 N. The K/sub m/ of the enzyme for methyl viologen is not affected by anions, while the V is greatly increased. H/sub 2/ oxidation coupled to methyl viologen reduction is also greatly stimulated by anions. However, when reduced ferredoxin is used as the electron donor to hydrogenase, there is a very strong inhibition of H/sub 2/ production by salts. In this case, the V of the enzyme is unaffected, but there is a large increase in the K/sub m/ of the enzyme for ferredoxin. The most inhibitory salt tested, KI, decreases hydrogenase activity by 93% at a concentration of 0.2 N.
Research Organization:
Solar Energy Research Inst., Golden, CO
DOE Contract Number:
AC02-77CH00178
OSTI ID:
5036660
Journal Information:
Arch. Biochem. Biophys.; (United States), Journal Name: Arch. Biochem. Biophys.; (United States) Vol. 213:1; ISSN ABBIA
Country of Publication:
United States
Language:
English