<?xml version="1.0" encoding="UTF-8"?><xml><records><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Park, Kwang-Hyun</style></author><author><style face="normal" font="default" size="100%">Jung, Jong-Hyun</style></author><author><style face="normal" font="default" size="100%">Park, Sung-Goo</style></author><author><style face="normal" font="default" size="100%">Lee, Myeong-Eun</style></author><author><style face="normal" font="default" size="100%">Holden, James F</style></author><author><style face="normal" font="default" size="100%">Park, Cheon-Seok</style></author><author><style face="normal" font="default" size="100%">Woo, Eui-Jeon</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Structural features underlying the selective cleavage of a novel exo-type maltose-forming amylase from Pyrococcus sp. ST04.</style></title><secondary-title><style face="normal" font="default" size="100%">Acta Crystallogr D Biol Crystallogr</style></secondary-title><alt-title><style face="normal" font="default" size="100%">Acta Crystallogr. D Biol. Crystallogr.</style></alt-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Amylases</style></keyword><keyword><style  face="normal" font="default" size="100%">Catalytic Domain</style></keyword><keyword><style  face="normal" font="default" size="100%">Maltose</style></keyword><keyword><style  face="normal" font="default" size="100%">Models, Molecular</style></keyword><keyword><style  face="normal" font="default" size="100%">Mutagenesis, Site-Directed</style></keyword><keyword><style  face="normal" font="default" size="100%">Protein Conformation</style></keyword><keyword><style  face="normal" font="default" size="100%">Proteolysis</style></keyword><keyword><style  face="normal" font="default" size="100%">Pyrococcus</style></keyword><keyword><style  face="normal" font="default" size="100%">Substrate Specificity</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2014</style></year><pub-dates><date><style  face="normal" font="default" size="100%">2014 Jun</style></date></pub-dates></dates><volume><style face="normal" font="default" size="100%">70</style></volume><pages><style face="normal" font="default" size="100%">1659-68</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">&lt;p&gt;A novel maltose-forming &amp;alpha;-amylase (PSMA) was recently found in the hyperthermophilic archaeon Pyrococcus sp. ST04. This enzyme shows &amp;lt;13% amino-acid sequence identity to other known &amp;alpha;-amylases and displays a unique enzymatic property in that it hydrolyzes both &amp;alpha;-1,4-glucosidic and &amp;alpha;-1,6-glucosidic linkages of substrates, recognizing only maltose units, in an exo-type manner. Here, the crystal structure of PSMA at a resolution of 1.8 &amp;Aring; is reported, showing a tight ring-shaped tetramer with monomers composed of two domains: an N-domain (amino acids 1-341) with a typical GH57 family (&amp;beta;/&amp;alpha;)7-barrel fold and a C-domain (amino acids 342-597) composed of &amp;alpha;-helical bundles. A small closed cavity observed in proximity to the catalytic residues Glu153 and Asp253 at the domain interface has the appropriate volume and geometry to bind a maltose unit, accounting for the selective exo-type maltose hydrolysis of the enzyme. A narrow gate at the putative subsite +1 formed by residue Phe218 and Phe452 is essential for specific cleavage of glucosidic bonds. The closed cavity at the active site is connected to a short substrate-binding channel that extends to the central hole of the tetramer, exhibiting a geometry that is significantly different from classical maltogenic amylases or &amp;beta;-amylases. The structural features of this novel exo-type maltose-forming &amp;alpha;-amylase provide a molecular basis for its unique enzymatic characteristics and for its potential use in industrial applications and protein engineering.&lt;/p&gt;
</style></abstract><issue><style face="normal" font="default" size="100%">Pt 6</style></issue></record></records></xml>