Stereochemistry of family 52 glycosyl hydrolases: a β‐xylosidase from Bacillus stearothermophilus T‐6 is a retaining enzyme

FEBS Letters

Shoham, Gil³  Zolotnitsky, Gennady¹  Shoham, Yuval²  Shulami, Smadar²  Baasov, Timor⁴  Solomon, Dmitry⁴  Belakhov, Valery⁴  Bravman, Tsafrir² 

[1] Interdepartmental Program in Biotechnology, Technion Israel Institute of Technology, Haifa 32000, Israel;Department of Food Engineering and Biotechnology, Technion Israel Institute of Technology, Haifa 32000, Israel;Department of Inorganic Chemistry and The Laboratory for Structural Chemistry and Biology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel;Department of Chemistry, Technion Israel Institute of Technology, Haifa 32000, Israel

关键词: β-Xylosidase;    Nuclear magnetic resonance;    Retaining mechanism;    Glycosyl hydrolase family 52;    Catalytic residue;    Bacillus stearothermophilus;   

DOI  :  10.1016/S0014-5793(01)02360-2

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

A β-xylosidase from Bacillus stearothermophilus T-6 assigned to the uncharacterized glycosyl hydrolase family 52 was cloned, overexpressed in Escherichia coli and purified. The enzyme showed maximum activity at 65°C and pH 5.6–6.3. The stereochemistry of the hydrolysis of p-nitrophenyl β-D-xylopyranoside was followed by ¹H-nuclear magnetic resonance. Time dependent spectrum analysis showed that the configuration of the anomeric carbon was retained, indicating that a retaining mechanism prevails in family 52 glycosyl hydrolases. Sequence alignment and site-directed mutagenesis enabled the identification of functionally important amino acid residues of which Glu337 and Glu413 are likely to be the two key catalytic residues involved in enzyme catalysis.

【 授权许可】

Unknown