a 2-oxocarboxylate + H(+) = an aldehyde + CO2 Binds 1 Mg(2+) per subunit. Binds 1 thiamine pyrophosphate per subunit. Homotetramer. Rapid and exclusive production of ethanol as the end product of sugar fermentation by the bacterium Zymononas mobilis is due to the presence of pyruvate decarboxylase. Belongs to the TPP enzyme family.