1vah

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Revision as of 02:25, 21 November 2007

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spinqualitylabelsall models 1vah, resolution 2.40Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

Crystal structure of the pig pancreatic-amylase complexed with r-nitrophenyl-a-D-maltoside

Overview

The X-ray structure analysis of a crystal of pig pancreatic alpha-amylase, soaked with a rho-nitrophenyl-alpha-D-maltoside (pNPG2) substrate showed a, pattern of electron density corresponding to the binding of a, rho-nitrophenol unit at subsite -2 of the active site. Binding of the, product to subsite -2 after hydrolysis of the pNPG2 molecules, may explain, the low catalytic efficiency of the hydrolysis of pNPG2 by PPA. Except a, small movement of the segment from residues 304-305 the typical, conformational changes of the "flexible loop" (303-309), that constitutes, the surface edge of the substrate binding cleft, were not observed in the, present complex structure. This result supports the hypothesis that, significant movement of the loop may depend on aglycone site being filled, (Payan and Qian, J. Protein Chen. 22: 275, 2003). Structural analyses have, shown that pancreatic alpha-amylases undergo an induced conformational, change of the catalytic residue Asp300 upon substrate binding; in the, present complex the catalytic residue is observed in its unliganded, orientation. The results suggest that the induced reorientation is likely, due to the presence of a sugar unit at subsite -1 and not linked to the, closure of the flexible surface loop. The crystal structure was refined at, 2.4 A resolution to an R factor of 17.55% (Rfree factor of 23.32%).

About this Structure

1VAH is a Single protein structure of sequence from Sus scrofa with CL, CA and NPO as ligands. Active as Alpha-amylase, with EC number 3.2.1.1 Full crystallographic information is available from OCA.

Reference

Crystal structure of the pig pancreatic alpha-amylase complexed with rho-nitrophenyl-alpha-D-maltoside-flexibility in the active site., Zhuo H, Payan F, Qian M, Protein J. 2004 Aug;23(6):379-87. PMID:15517985

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