Gene Cloning, Purification, and Characterization of 2, 3-Diaminopropionate Ammonia-lyase from Escherichia coli(Biochemistry & Molecular Biology)

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2, 3-Diaminopropionate ammonia-lyase (DAPAL), which catalyzes α, β-elimination of 2, 3-diaminopropionate regardless of its stereochemistry, was purified from Salmonella typhimurium. We cloned the Escherichia coli ygeX gene encoding a putative DAPAL and purified the gene product to homogeneity. The protein obtained contained pyridoxal 5'-phosphate and was composed of two identical subunits with a calculated molecular weight of 43,327. It catalyzed the α, β-elimination of both D- and L-2, 3-diaminopropionate. The results confirmed that ygeX encoded DAPAL. The enzyme acted on D-serine, but its catalytic efficiency was only 0.5% that with D-2, 3-diaminopropionate. The enzymologic properties of E. coli DAPAL resembled those of Salmonella DAPAL, except that L-serine, D- and L-β-Cl-alanine were inert as substrates of the enzyme from E. coli. DAPAL had significant sequence similarity with the catalytic domain of L-threonine dehydratase, which is a member of the fold-type II group of pyridoxal phosphate enzymes, together with D-serine dehydratase and mammalian serine racemase.
社団法人日本農芸化学会の論文
2002-12-23