| Literature DB >> 19269582 |
Jiansong Ju1, Shujing Xu, Jianxin Wen, Gang Li, Kouhei Ohnishi, Yanfen Xue, Yanhe Ma.
Abstract
An open reading frame of 1100 bp in the partially sequenced genome sequence of alkaliphilic Bacillus pseudofirmus OF4 was identified as a putative alanine racemase gene (dadX(OF4)), which was cloned and expressed in Escherichia coli BL21 (DE3). The encoded protein DadX(OF4) was purified to homogeneity by His(6)-tag affinity column, gel filtration and ion-exchange chromatography. The amino acid sequence has highest identity with the known alanine racemase from Oceanobacillus iheyensis HTE831 (48%). The protein was a dimeric, endogenous PLP-dependent enzyme, which was demonstrated by absorption spectra and enzyme activity with or without PLP. The racemization temperature optimum was 40 degrees C and the optimal pH was 10.5. The kinetic parameters K(m) and V(max) at 40 degrees C of alanine racemase, determined by HPLC analysis, were 41.79 mM, 10,500 units/mg for L-alanine and 14.91 mM, 3708 units/mg for D-alanine, respectively.Entities:
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Year: 2009 PMID： 19269582 DOI： 10.1016/j.jbiosc.2008.11.005
Source DB: PubMed Journal: J Biosci Bioeng ISSN： 1347-4421 Impact factor: 2.894