TY - JOUR
T1 - A new amino acid racemase with threonine α-epimerase activity from Pseudomonas putida
T2 - Purification and characterization
AU - Lim, Y. H.
AU - Yokoigawa, K.
AU - Esaki, N.
AU - Soda, K.
PY - 1993
Y1 - 1993
N2 - 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.
AB - 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.
UR - http://www.scopus.com/inward/record.url?scp=0027197398&partnerID=8YFLogxK
U2 - 10.1128/jb.175.13.4213-4217.1993
DO - 10.1128/jb.175.13.4213-4217.1993
M3 - Article
C2 - 8320235
AN - SCOPUS:0027197398
SN - 0021-9193
VL - 175
SP - 4213
EP - 4217
JO - Journal of Bacteriology
JF - Journal of Bacteriology
IS - 13
ER -