Department of Biotechnology and Food Engineering, Technion-Israel Institute of Technology, Haifa 32000, Israel.
FEBS Lett. 2012 Jul 30;586(16):2436-42. doi: 10.1016/j.febslet.2012.05.062. Epub 2012 Jun 8.
In this study we demonstrate that the abp gene in Geobacillus stearothermophilus T-6 encodes a family 27 glycoside hydrolase β-L-arabinopyranosidase. The catalytic constants towards the chromogenic substrate pNP-β-L-arabinopyranoside were 0.8±0.1 mM, 6.6±0.3 s(-1), and 8.2±0.3 s(-1) mM(-1) for K(m), k(cat) and k(cat)/K(m), respectively. (13)C NMR spectroscopy unequivocally showed that Abp is capable of removing β-L-arabinopyranose residues from the natural arabino-polysaccharide, larch arabinogalactan. Most family 27 enzymes are active on galactose and contain a conserved Asp residue, whereas in Abp this residue is Ile67, which shifts the specificity of the enzyme towards arabinopyranoside.
在这项研究中，我们证明了嗜热脂肪地芽孢杆菌 T-6 中的 abp 基因编码一种属于家族 27 的糖苷水解酶β-L-阿拉伯吡喃糖苷酶。对于显色底物 pNP-β-L-阿拉伯吡喃糖苷，其催化常数分别为 0.8±0.1 mM、6.6±0.3 s(-1) 和 8.2±0.3 s(-1) mM(-1)，对应的是 K(m)、k(cat) 和 k(cat)/K(m)。(13)C NMR 光谱学明确表明，Abp 能够从天然阿拉伯聚糖，落叶松阿拉伯半乳聚糖中去除β-L-阿拉伯吡喃糖残基。大多数家族 27 酶对半乳糖有活性，并且含有保守的天冬氨酸残基，而在 Abp 中，该残基是异亮氨酸 67，这使酶的特异性向阿拉伯吡喃糖苷转移。
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