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Abstract
Summary: Pyruvate decarboxylase from the obligate anaerobe Sarcina ventriculi was purified eightfold. The subunit M r was 57000 ± 3000 as estimated from SDS-PAGE, and the native M r estimated by gel filtration on a Superose 6 column was 240000, indicating that the enzyme is a tetramer. The M r values are comparable to those for pyruvate decarboxylase from Zymomonas mobilis and Saccharomyces cerevisiae, which are also tetrameric enzymes. The enzyme was oxygen stable, and had a pH optimum within the range 6·3-6·7. It displayed sigmoidal kinetics for pyruvate, with a S 0·5 of 13 mm, kinetic properties also found for pyruvate decarboxylase from yeast and differing from the Michaelis-Menten kinetics of the enzyme from Z. mobilis. No activators were found. p-Chloromercuri-benzoate inhibited activity and the inhibition was reversed by the addition of dithiothreitol, indicating that cysteine is important in the active site. The N-terminal amino acid sequence of pyruvate decarboxylase was more similar to the sequence of S. cerevisiae than Z. mobilis pyruvate decarboxylase.
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Funding
- National Science Foundation and Technology Center (Award DE-FG02- 87ER-13719)