Crystallization and preliminary X-ray crystallographic analysis of α-glucosidase HaG from Halomonas sp. strain H11

The α-glucosidase HaG from the halophilic bacterium Halomonas sp. strain H11 catalyzes the hydrolysis of the glucosidic linkage at the nonreducing end of α-glucosides, such as maltose and sucrose, to release α-glucose. Based on its amino-acid sequence, this enzyme is classified as a member of glycoside hydrolase family 13. HaG has three unique characteristics: (i) a very narrow substrate specificity, almost exclusively hydrolyzing disaccharides; (ii) activation by monovalent cations, such as K+, Rb+, Cs+ and NH4+; and (iii) high transfer activity of the glucose moiety to the OH group of low-molecular-weight compounds, including glycerol and 6-gingerol. Crystallographic studies have been performed in order to understand these special features. An expression vector was constructed and recombinant HaG protein was overexpressed, purified and crystallized. A data set to 2.15 Å resolution was collected and processed. The crystal belonged to space group P212121, with unit-cell parameters a = 60.2, b = 119.2, c = 177.2 Å. The structure has been determined by molecular replacement using the isomaltulose synthase PalI as the search model (PDB entry 1m53).

Source: Acta Crystallographica Section F - March 25, 2014 Category: Biochemistry Authors: Shen, X.Saburi, W.Gai, Z.-Q.Komoda, K.Yu, J.Ojima-Kato, T.Kido, Y.Matsui, H.Mori, H.Yao, M. Tags: HaG Halomonas sp. strain H11 crystallization communications Source Type: research