1esw
From Proteopedia
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'''X-RAY STRUCTURE OF ACARBOSE BOUND TO AMYLOMALTASE FROM THERMUS AQUATICUS. IMPLICATIONS FOR THE SYNTHESIS OF LARGE CYCLIC GLUCANS''' | '''X-RAY STRUCTURE OF ACARBOSE BOUND TO AMYLOMALTASE FROM THERMUS AQUATICUS. IMPLICATIONS FOR THE SYNTHESIS OF LARGE CYCLIC GLUCANS''' | ||
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[[Category: Takaha, T.]] | [[Category: Takaha, T.]] | ||
[[Category: Terada, Y.]] | [[Category: Terada, Y.]] | ||
| - | [[Category: | + | [[Category: Acarbose]] |
| - | [[Category: | + | [[Category: Alpha-amylase family]] |
| - | + | [[Category: Glucanotransferase]] | |
| - | [[Category: | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 15:29:00 2008'' |
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| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | |
Revision as of 12:29, 2 May 2008
X-RAY STRUCTURE OF ACARBOSE BOUND TO AMYLOMALTASE FROM THERMUS AQUATICUS. IMPLICATIONS FOR THE SYNTHESIS OF LARGE CYCLIC GLUCANS
Overview
As a member of the alpha-amylase superfamily of enzymes, amylomaltase catalyzes either the transglycosylation from one alpha-1,4 glucan to another or an intramolecular cyclization. The latter reaction is typical for cyclodextrin glucanotransferases. In contrast to these enzymes, amylomaltase catalyzes the formation of cyclic glucans with a degree of polymerization larger than 22. To characterize the factors that determine the size of the synthesized cycloamyloses, we have analyzed the X-ray structure of amylomaltase from Thermus aquaticus in complex with the inhibitor acarbose, a maltotetraose derivative, at 1.9 A resolution. Two acarbose molecules are bound to the enzyme, one in the active site groove at subsite -3 to +1 and a second one approximately 14 A away from the nonreducing end of the acarbose bound to the catalytic site. The inhibitor bound to the catalytic site occupies subsites -3 to +1. Unlike the situation in other enzymes of the alpha-amylase family, the inhibitor is not processed and the inhibitory cyclitol ring of acarbose, which mimicks the half chair conformation of the transition state, does not bind to catalytic subsite -1. The minimum ring size of cycloamyloses produced by this enzyme is proposed to be determined by the distance of the specific substrate binding sites at the active site and near Tyr54 and by the size of the 460s loop. The 250s loop might be involved in binding of the substrate at the reducing end of the scissile bond.
About this Structure
1ESW is a Single protein structure of sequence from Thermus aquaticus. Full crystallographic information is available from OCA.
Reference
X-ray structure of acarbose bound to amylomaltase from Thermus aquaticus. Implications for the synthesis of large cyclic glucans., Przylas I, Terada Y, Fujii K, Takaha T, Saenger W, Strater N, Eur J Biochem. 2000 Dec;267(23):6903-13. PMID:11082203 Page seeded by OCA on Fri May 2 15:29:00 2008
