
Full text loading...
Summary: The pyruvate dehydrogenase complex from the thermophilic bacterium Thermus aquaticus was purified by Triton X-100 extraction and chromatography on phenyl-Sepharose CL-4B and HPLC-hydroxyapatite. The electrophoretic pattern of the purified enzyme complex was similar to that of the enzyme complex from Bacillus subtilis, with four bands: the α-chain (M r 39600) and β-chain (M r 37500) of the pyruvate dehydrogenase component, the dihydrolipoamide acetytransferase component (M r 58500) and the dihydrolipoamide dehydrogenase component (M r 53900). Antibodies against the purified T. aquaticus pyruvate dehydrogenase complex cross-reacted with the enzyme complex from B. subtilis and, to a minor extent, with that from bovine heart. No cross-reactivity could be observed with the enzyme complex from Escherichia coli. The T. aquaticus enzyme complex had a temperature maximum at 72°C. 2-Oxobutyrate was a poor substrate and other 2-oxoacids were competitive inhibitors of the overall reaction. Long-chain 2-oxoacids showed a greater inhibitory effect, possibly caused by hydrophobic interactions. GTP inhibited the enzyme activity. Regulation of the pyruvate dehydrogenase complex from T. aquaticus by allosteric mechanisms or by reversible phosphorylation could not be demonstrated.
Article metrics loading...
Full text loading...
References
Data & Media loading...