1WP6

Crystal structure of maltohexaose-producing amylase from alkalophilic Bacillus sp.707.

Summary for 1WP6

• Entry DOI: 10.2210/pdb1wp6/pdb
• Descriptor: Glucan 1,4-alpha-maltohexaosidase, CALCIUM ION, SODIUM ION, ... (6 entities in total)
• Functional Keywords: alpha-amylase, maltohexaose, hydrolase
• Biological source: Bacillus sp.
• Cellular location: Secreted: P19571
• Total number of polymer chains: 1
• Total formula weight: 55799.23

Authors

Kanai, R.,Haga, K.,Akiba, T.,Yamane, K.,Harata, K. (deposition date: 2004-08-31, release date: 2004-11-30, Last modification date: 2023-10-25)

Primary citation

Kanai, R.,Haga, K.,Akiba, T.,Yamane, K.,Harata, K.
Biochemical and crystallographic analyses of maltohexaose-producing amylase from alkalophilic Bacillus sp. 707
Biochemistry, 43:14047-14056, 2004

PubMed Abstract: Maltohexaose-producing amylase, called G6-amylase (EC 3.2.1.98), from alkalophilic Bacillus sp.707 predominantly produces maltohexaose (G6) from starch and related alpha-1,4-glucans. To elucidate the reaction mechanism of G6-amylase, the enzyme activities were evaluated and crystal structures were determined for the native enzyme and its complex with pseudo-maltononaose at 2.1 and 1.9 A resolutions, respectively. The optimal condition for starch-degrading reaction activity was found at 45 degrees C and pH 8.8, and the enzyme produced G6 in a yield of more than 30% of the total products from short-chain amylose (DP = 17). The crystal structures revealed that Asp236 is a nucleophilic catalyst and Glu266 is a proton donor/acceptor. Pseudo-maltononaose occupies subsites -6 to +3 and induces the conformational change of Glu266 and Asp333 to form a salt linkage with the N-glycosidic amino group and a hydrogen bond with secondary hydroxyl groups of the cyclitol residue bound to subsite -1, respectively. The indole moiety of Trp140 is stacked on the cyclitol and 4-amino-6-deoxyglucose residues located at subsites -6 and -5 within a 4 A distance. Such a face-to-face short contact may regulate the disposition of the glucosyl residue at subsite -6 and would govern the product specificity for G6 production.

PubMed: 15518553
DOI: 10.1021/bi048489m

Experimental method

X-RAY DIFFRACTION (2.1 Å)