A new amino acid racemase with threonine α-epimerase activity from Pseudomonas putida

Purification and characterization

Young Hee Lim, K. Yokoigawa, N. Esaki, K. Soda

Research output: Contribution to journalArticle

36 Citations (Scopus)

Abstract

We have found that Pseudomonas putida ATCC 17642 cells grown in a medium containing D-threonine as the sole nitrogen source produce an enzyme that catalyzes epimerization of threonine. Proton nuclear magnetic resonance analysis of the enzyme reaction in deuterium oxide clearly showed epimerization from L- to D-allo-threonine and also from D- to L-allo- threonine. This is the first example of an enzyme that was clearly shown to epimerize threonine. The enzyme has been purified to homogeneity, which was shown by polyacrylamide gel electrophoresis. The enzyme has a molecular weight of about 82,000 and consists of two subunits identical in molecular weight (about 41,000). The enzyme contains 1 mol of pyridoxal 5'-phosphate per mol of subunit as a cofactor, and its absorption spectrum exhibits absorption maxima at 280 and 420 nm. The enzyme catalyzes not only epimerization of threonine by stereoconversion at the α position but also racemization of various amino acids, except acidic and aromatic amino acids. The enzyme is similar to amino acid racemase with low substrate specificity (EC 5.1.1.10) in enzymological properties but is distinct from it in the action on threonine.

Original languageEnglish
Pages (from-to)4213-4217
Number of pages5
JournalJournal of Bacteriology
Volume175
Issue number13
Publication statusPublished - 1993 Jan 1
Externally publishedYes

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Amino Acid Isomerases
Racemases and Epimerases
Pseudomonas putida
Threonine
Enzymes
Molecular Weight
Deuterium Oxide
Acidic Amino Acids
Aromatic Amino Acids
Pyridoxal Phosphate
Substrate Specificity
Protons
Polyacrylamide Gel Electrophoresis
Magnetic Resonance Spectroscopy
Nitrogen

ASJC Scopus subject areas

  • Applied Microbiology and Biotechnology
  • Immunology

Cite this

A new amino acid racemase with threonine α-epimerase activity from Pseudomonas putida : Purification and characterization. / Lim, Young Hee; Yokoigawa, K.; Esaki, N.; Soda, K.

In: Journal of Bacteriology, Vol. 175, No. 13, 01.01.1993, p. 4213-4217.

Research output: Contribution to journalArticle

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