, Volume 152, Issue 6, pp 584-588

Isolation and characterization of oxaloacetate decarboxylase of Salmonella typhimurium, a sodium ion pump

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Abstract

Anaerobic growth of Salmonella typhimurium on citrate is Na+-dependent and requires induction of the necessary enzymes during a 20–40 h lag phase. The citrate fermentation pathway involves citrate lyase and oxaloacetate decarboxylase. The decarboxylase is a membrane-bound. Na+-activated, biotin-containing enzyme that functions as a Na+ pump. Oxaloacetate decarboxylase was isolated by affinity chromatography of a Triton X-100 extract of the bacterial membranes on avidin-Sepharose. The enzyme consists of three subunits α, β, γ, with apparent molecular weights of 63800, 34500 and 10600. The α-chain contains a covalently attached biotin group and binds to antibodies raised against the α-subunit of oxaloacetate decarboxylase from Klebsiella pneumoniae. The Na+ transport function was reconstituted by incorporation of the puriried enzyme into proteoliposomes.