Specific ligand enhancement of the affinity of E. coli pyruvate oxidase for dipalmitoyl phosphatidylcholine.

H. L. Schrock, R. B. Gennis

Research output: Contribution to journalArticlepeer-review


Pyruvate oxidase (pyruvate: ferricytochrome b1 oxidoreductase, EC is a peripheral membrane flavoenzyme isolated from Escherichia coli. The enzyme catalyzes the oxidative decarboxylation of pyruvate to acetate plus CO2, and is coupled to the E. coli electron traansport chain. In vitro, pyruvate oxidase activity is measured spectrophotometrically using ferricyanide as an electron acceptor. In the presence of dipalmitoyl phosphatidylcholine or a number of other phospholipids, or detergents, the enzymatic specific activity is enhanced about 25-fold. In this paper the interaction between pyruvate oxidase and dipalmitoyl phosphatidylcholine is examined. It is demonstrated that the presence of the ligands involved in catalysis has a substantial influence on the affinity between pyruvate oxidase and dipalmitoyl phosphatidylcholine. In the absence of the substrate (pyruvate) and cofactor (thiamin pyrophosphate) there is no detectable complex formation. However, when both ligands are present, a condition which results in the reduction of the flavoprotein, the interaction between the protein and phospholipid is greatly enhanced. It is clearly shown that the protein-lipid interaction is dramatically modulated by the ligands bound at the catalytic active site on the enzyme and/or by the oxidation-reduction state of the flavin.

Original languageEnglish (US)
Pages (from-to)215-220
Number of pages6
JournalBBA - Biochimica et Biophysica Acta
Issue number1
StatePublished - Jul 10 1980
Externally publishedYes


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