A peripheral cell membrane enzyme that catalyzes the oxidative decarboxylation of pyruvate to form acetate and CO(2). It channels electrons from the cytoplasm to the respiratory chain at the cell membrane via ubiquinone (By similarity) (PubMed:18988747, PubMed:2663858, PubMed:365232). The main pathway for acetate production during stationary phase (PubMed:16080684). a ubiquinone + H2O + pyruvate = a ubiquinol + acetate + CO2 Binds 1 FAD per subunit. Binds 1 Mg(2+) ion per subunit; Mn(2+) is also functional. The Me2+-thiamine diphosphate complex is the true cofactor. Binds 1 thiamine pyrophosphate per subunit. The C-terminus inhibits activity; it has to move for the enzyme to be active (PubMed:18988747). Activated by lipid-binding, which occurs via the C-terminus; detergents also activate the enzyme (PubMed:334770, PubMed:334771, PubMed:2663858, PubMed:18988747). Specifically activated by palmitic acid; 12 (lauric) and 14-carbon (myristic) fatty acids as well as unsaturated 16 and 18-carbon fatty acids also activate the enzyme (PubMed:6385860). Lipid affinity is increased in the presence of pyruvate plus the thiamine pyrophosphate cofactor (PubMed:334770, PubMed:334771, PubMed:2663858, PubMed:18988747). kcat is 7 sec(-1) for non-activated, 200 sec(-1) for activated form. Homotetramer. Activity is maximal in late exponential and early stationary phase (at protein level) (PubMed:8022274, PubMed:16080684). Expression increases at pH 6.0 (PubMed:16080684). Under control of rpoS (at protein level). Transcribed at lower levels during anaerobic growth (PubMed:8022274). Has 4 domains; the Pyr domain which binds the pyrimidine moiety of the thiamine pyrophosphate cofactor, the FAD-binding domain, the PP-binding domain which binds the pyrophosphate portion of thiamine pyrophosphate and the C-terminal membrane binding region, which includes the in vitro-derived alpha-peptide (residues 550-572). The C-terminus is held closely against the rest of the protein and covers the active site; during activation it detaches from the rest of the protein and folds into an amphipathic helix upon membrane binding. Comparison of full-length and proteolyzed structures shows activation is a result of conformational changes that expose the active site. Activated by limited proteolytic digestion in vitro. This cleavage produces a peptide (alpha-peptide) and mimics the activation of enzyme by phospholipids (PubMed:5336022, PubMed:3902830, PubMed:334770, PubMed:334771). Protease activation and lipid-activation are mutually exclusive. Proteolytic cleavage results in the loss of the high affinity lipid-binding site of the enzyme; the cleaved protein is no longer activated by lipids or detergents (PubMed:334771, PubMed:2663858). The proteolytically cleaved enzyme does not represent a functional cleavage in vivo (PubMed:3527254). Not essential it can be deleted. Belongs to the TPP enzyme family.