Purification and characterization of pyruvate decarboxylase from Sarcina ventriculi. |
| |
Authors: | S E Lowe J G Zeikus |
| |
Affiliation: | Department of Biochemistry, Michigan State University, East Lansing 48824. |
| |
Abstract: | Pyruvate decarboxylase from the obligate anaerobe Sarcina ventriculi was purified eightfold. The subunit Mr was 57,000 +/- 3000 as estimated from SDS-PAGE, and the native Mr estimated by gel filtration on a Superose 6 column was 240,000, indicating that the enzyme is a tetramer. The Mr 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 S0.5 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-Chloromercuribenzoate 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. |
| |
Keywords: | |
|
|