1g66
From Proteopedia
OCA (Talk | contribs)
(New page: 200px<br /><applet load="1g66" size="450" color="white" frame="true" align="right" spinBox="true" caption="1g66, resolution 0.90Å" /> '''ACETYLXYLAN ESTERASE...)
Next diff →
Revision as of 13:37, 20 November 2007
|
ACETYLXYLAN ESTERASE AT 0.90 ANGSTROM RESOLUTION
Overview
Acetylxylan esterase (AXEII; 207 amino acids) from Penicillium, purpurogenum has substrate specificities toward acetate esters of, d-xylopyranose residues in xylan and belongs to a new class of alpha/beta, hydrolases. The crystal structure of AXEII has been determined by single, isomorphous replacement and anomalous scattering, and refined at 0.90- and, 1.10-A resolutions with data collected at 85 K and 295 K, respectively., The tertiary structure consists of a doubly wound alpha/beta sandwich, having a central six-stranded parallel beta-sheet flanked by two parallel, alpha-helices on each side. The catalytic residues Ser(90), His(187), and, Asp(175) are located at the C-terminal end of the sheet, an exposed region, of the molecule. The serine and histidine side chains in the 295 K, structure show the frequently observed conformations in which Ser(90) is, trans and the hydroxyl group is in the plane of the imidazole ring of, His(187). However, the structure at 85 K displays an additional, conformation in which Ser(90) side-chain hydroxyl is away from the plane, of the imidazole ring of His(187). The His(187) side chain forms a, hydrogen bond with a sulfate ion and adopts an altered conformation. The, only other known hydrolase that has a similar tertiary structure is, Fusarium solani cutinase. The exposed nature of the catalytic triad, suggests that AXEII is a pure esterase, i.e. an alpha/beta hydrolase with, specificity for nonlipidic polar substrates.
About this Structure
1G66 is a Single protein structure of sequence from Penicillium purpurogenum with SO4 and GOL as ligands. Active as Acetylesterase, with EC number 3.1.1.6 Full crystallographic information is available from OCA.
Reference
Multiple conformations of catalytic serine and histidine in acetylxylan esterase at 0.90 A., Ghosh D, Sawicki M, Lala P, Erman M, Pangborn W, Eyzaguirre J, Gutierrez R, Jornvall H, Thiel DJ, J Biol Chem. 2001 Apr 6;276(14):11159-66. Epub 2000 Dec 29. PMID:11134051
Page seeded by OCA on Tue Nov 20 15:44:41 2007
