PJB-1982-1
Aldehyde dehydrogenase from photohetero- Trophically grown rhodospirillum rubrum
Ashraf H.
chaudhry and albert W. frenkel
Abstract
Extracts from cells of rhodospirillum
rubrum cultured photohetero-
trophically under anaerobic conditions exhibits an NAD+-dependent , soluble aldehyde dehydrogenase which catalyses the dehydrogenation of acetaldehyde to acetate (aldehyde: NAD+ oxidoreductase . EC 1.2, 1.3 ) the enzyme is NAD+ specific with thw aldehydes tested, no activity is observed with NADP+ or in the absence of NAD+. Sulfhydryl reagents markedly increase the aldehyde dehydrogenase activity. For initial reaction rates of acetaldehyde dehydrogenation the optimum activity of the enzyme is between pH 9.0 to 9.5 , with an apparent michaelis constant for acetaldehyde of
10-5 M. no requirements for potassium or
orthophosphate are apparent . extracts from cells cultured anaerobically on ethanol, as the sole carbon, source, exhibit five to ten times the specific aldehyde dehydrogenase activity compard to cell cultured on malate plus glutamate . this increase in the specific activity of aldehyde dehydrogenase preparations from cells cultured on ethanol is inhibited by proflavin or chloramphenicol . the evidence suggests that the aldehyde dehydrogenase in R. rubrum ia sn inducible enzyme.
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