5ca3: Difference between revisions

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== Function ==

[[http://www.uniprot.org/uniprot/YGJK_ECOLI YGJK_ECOLI]] Glucoside hydrolase that cleaves the alpha-1,3-glucosidic linkage in nigerose. Has very low activity towards maltooligosaccharides, soluble starch, nigerotriose, kojibiose and trehalose.

== Publication Abstract from PubMed ==

Glycoside hydrolases are divided into two groups, known as inverting and retaining enzymes, based on their hydrolytic mechanisms. Glycoside hydrolase family 63 (GH63) is composed of inverting alpha-glycosidases, which act mainly on alpha-glucosides. We previously found that Escherichia coli GH63 enzyme, YgjK, can hydrolyze 2-O-alpha-d-glucosyl-d-galactose. Two constructed glycosynthase mutants, D324N and E727A, which catalyze the transfer of a beta-glucosyl fluoride donor to galactose, lactose, and melibiose. Here, we determined the crystal structures of D324N and E727A soaked with a mixture of glucose and lactose at 1.8- and 2.1-A resolutions, respectively. Because glucose and lactose molecules are found at the active sites in both structures, it is possible that these structures mimic the enzyme-product complex of YgjK. A glucose molecule found at subsite -1 in both structures adopts an unusual 1S3 skew-boat conformation. Comparison between these structures and the previously determined enzyme-substrate complex structure reveals that the glucose pyranose ring might be distorted immediately after nucleophilic attack by a water molecule. These structures represent the first enzyme-product complex for the GH63 family, as well as the structurally-related glycosidases, and it may provide insight into the catalytic mechanism of these enzymes.

Crystal structure of the enzyme-product complex reveals sugar ring distortion during catalysis by family 63 inverting alpha-glycosidase.,Miyazaki T, Nishikawa A, Tonozuka T J Struct Biol. 2016 Sep 26. pii: S1047-8477(16)30204-0. doi:, 10.1016/j.jsb.2016.09.015. PMID:27688023<ref>PMID:27688023</ref>

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.<br>

</div>

== References ==

__TOC__

</StructureSection>

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 == Function ==
 [[http://www.uniprot.org/uniprot/YGJK_ECOLI YGJK_ECOLI]] Glucoside hydrolase that cleaves the alpha-1,3-glucosidic linkage in nigerose. Has very low activity towards maltooligosaccharides, soluble starch, nigerotriose, kojibiose and trehalose.
+<div style="background-color:#fffaf0;">
+== Publication Abstract from PubMed ==
+Glycoside hydrolases are divided into two groups, known as inverting and retaining enzymes, based on their hydrolytic mechanisms. Glycoside hydrolase family 63 (GH63) is composed of inverting alpha-glycosidases, which act mainly on alpha-glucosides. We previously found that Escherichia coli GH63 enzyme, YgjK, can hydrolyze 2-O-alpha-d-glucosyl-d-galactose. Two constructed glycosynthase mutants, D324N and E727A, which catalyze the transfer of a beta-glucosyl fluoride donor to galactose, lactose, and melibiose. Here, we determined the crystal structures of D324N and E727A soaked with a mixture of glucose and lactose at 1.8- and 2.1-A resolutions, respectively. Because glucose and lactose molecules are found at the active sites in both structures, it is possible that these structures mimic the enzyme-product complex of YgjK. A glucose molecule found at subsite -1 in both structures adopts an unusual 1S3 skew-boat conformation. Comparison between these structures and the previously determined enzyme-substrate complex structure reveals that the glucose pyranose ring might be distorted immediately after nucleophilic attack by a water molecule. These structures represent the first enzyme-product complex for the GH63 family, as well as the structurally-related glycosidases, and it may provide insight into the catalytic mechanism of these enzymes.
+Crystal structure of the enzyme-product complex reveals sugar ring distortion during catalysis by family 63 inverting alpha-glycosidase.,Miyazaki T, Nishikawa A, Tonozuka T J Struct Biol. 2016 Sep 26. pii: S1047-8477(16)30204-0. doi:, 10.1016/j.jsb.2016.09.015. PMID:27688023<ref>PMID:27688023</ref>
+From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
+</div>
+<div class="pdbe-citations 5ca3" style="background-color:#fffaf0;"></div>
+== References ==
+<references/>
 __TOC__
 </StructureSection>