1wu4: Difference between revisions

[[Image:1wu4.gif|left|200px]]<br /><applet load="1wu4" size="350" color="white" frame="true" align="right" spinBox="true"  

Reducing end xylose-releasing exo-oligoxylanase from Bacillus halodurans C-125 (Rex) hydrolyzes xylooligosaccharides whose degree of polymerization is greater than or equal to 3, releasing the xylose unit at the reducing end. It is a unique exo-type glycoside hydrolase that recognizes the xylose unit at the reducing end in a very strict manner, even discriminating the beta-anomeric hydroxyl configuration from the alpha-anomer or 1-deoxyxylose. We have determined the crystal structures of Rex in unliganded and complex forms at 1.35-2.20-A resolution and revealed the structural aspects of its three subsites ranging from -2 to +1. The structure of Rex was compared with those of endo-type enzymes in glycoside hydrolase subfamily 8a (GH-8a). The catalytic machinery of Rex is basically conserved with other GH-8a enzymes. However, subsite +2 is blocked by a barrier formed by a kink in the loop before helix alpha10. His-319 in this loop forms a direct hydrogen bond with the beta-hydroxyl of xylose at subsite +1, contributing to the specific recognition of anomers at the reducing end.

1WU4 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Bacteria Bacteria] with <scene name='pdbligand=NI:'>NI</scene> and <scene name='pdbligand=GOL:'>GOL</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Oligosaccharide_reducing-end_xylanase Oligosaccharide reducing-end xylanase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.2.1.156 3.2.1.156] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1WU4 OCA].  

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