1UH2

Thermoactinomyces vulgaris R-47 alpha-amylase/malto-hexaose complex

Summary for 1UH2

• Entry DOI: 10.2210/pdb1uh2/pdb
• Related: 1UH3 1UH4 1ji1
• Related PRD ID: PRD_900010 PRD_900030
• Descriptor: alpha-amylase I, alpha-D-glucopyranose-(1-4)-alpha-D-glucopyranose-(1-4)-alpha-D-glucopyranose-(1-4)-alpha-D-glucopyranose-(1-4)-alpha-D-glucopyranose, alpha-D-glucopyranose-(1-4)-alpha-D-glucopyranose-(1-4)-alpha-D-glucopyranose-(1-4)-alpha-D-glucopyranose, ... (5 entities in total)
• Functional Keywords: starch binding domain, hydrolase
• Biological source: Thermoactinomyces vulgaris
• Total number of polymer chains: 1
• Total formula weight: 73390.44

Authors

Abe, A.,Tonozuka, T.,Sakano, Y.,Kamitori, S. (deposition date: 2003-06-23, release date: 2004-01-13, Last modification date: 2023-12-27)

Primary citation

Abe, A.,Tonozuka, T.,Sakano, Y.,Kamitori, S.
Complex Structures of Thermoactinomyces vulgaris R-47 alpha-Amylase 1 with Malto-oligosaccharides Demonstrate the Role of Domain N Acting as a Starch-binding Domain
J.Mol.Biol., 335:811-822, 2004

PubMed Abstract: The X-ray structures of complexes of Thermoactinomyces vulgaris R-47 alpha-amylase 1 (TVAI) with an inhibitor acarbose and an inactive mutant TVAI with malto-hexaose and malto-tridecaose have been determined at 2.6, 2.0 and 1.8A resolution, and the structures have been refined to R-factors of 0.185 (R(free)=0.225), 0.184 (0.217) and 0.164 (0.200), respectively, with good chemical geometries. Acarbose binds to the catalytic site of TVAI, and interactions between acarbose and the enzyme are very similar to those found in other structure-solved alpha-amylase/acarbose complexes, supporting the proposed catalytic mechanism. Based on the structure of the TVAI/acarbose complex, the binding mode of pullulan containing alpha-(1,6) glucoside linkages could be deduced. Due to the structural difference caused by the replaced amino acid residue (Gln396 for Glu) in the catalytic site, malto-hexaose and malto-tridecaose partially bind to the catalytic site, giving a mimic of the enzyme/product complex. Besides the catalytic site, four sugar-binding sites on the molecular surface are found in these X-ray structures. Two sugar-binding sites in domain N hold the oligosaccharides with a regular helical structure of amylose, which suggests that the domain N is a starch-binding domain acting as an anchor to starch in the catalytic reaction of the enzyme. An assay of hydrolyzing activity for the raw starches confirmed that TVAI can efficiently hydrolyze raw starch.

PubMed: 14687576
DOI: 10.1016/j.jmb.2003.10.078

Experimental method

X-RAY DIFFRACTION (2 Å)