Purification of branched-chain amino acid aminotransferase from Helicobacter pylori NCTC 11637.
Branched-chain amino acid aminotransferase was purified by several column chromatographies from Helicobacter pylori NCTC 11637, and the N-terminal amino acid sequence was analyzed. The enzyme gene was sequenced based on a putative branched-chain amino acid aminotransferase gene, ilvE of H. pylori 26695, and the whole amino acid sequence was deduced from the nucleotide sequence. The enzyme existed in a homodimer with a calculated subunit molecular weight (MW) of 37,539 and an isoelectric point (pI) of 6.47. The enzyme showed high affinity to 2-oxoglutarate (K (m) = 0.085 mM) and L-isoleucine (K (m) = 0.34 mM), and V (max) was 27.3 micromol/min/mg. The best substrate was found to be L-isoleucine followed by L-leucine and L-valine. No activity was shown toward the D-enantiomers of these amino acids. The optimal pH and temperature were pH 8.0 and 37 degrees C, respectively.
Saito
M
M
Department of Materials and Applied Chemistry, College of Science and Technology, Nihon University, Tokyo, Japan.
Nishimura
K
K
Wakabayashi
S
S
Kurihara
T
T
Nagata
Y
Y
D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification*; D016480:Helicobacter pylori / Q000201:enzymology*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007526:Isoelectric Point; D007656:Ketoglutaric Acids / Q000378:metabolism; D008969:Molecular Sequence Data; D020836:Protein Structure, Quaternary; D013379:Substrate Specificity; D000637:Transaminases / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification*; D014633:Valine / Q000378:metabolism
D001426:Bacterial Proteins; D007656:Ketoglutaric Acids; D000637:Transaminases; C019798:branched-chain-amino-acid transaminase; D014633:Valine