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Publication Abstract from PubMed

The crystal structures of the wild type and catalytic mutant Asp-312-->Gly in complex with isomaltohexaose of endo-1,6-dextranase from the thermophilic bacterium Thermoanaerobacter pseudethanolicus (TpDex), belonging to the glycoside hydrolase family 66, were determined. TpDex consists of three structural domains, a catalytic domain comprising an (beta/alpha)8-barrel and two beta-domains located at both N- and C-terminal ends. The isomaltohexaose-complex structure demonstrated that the isomaltohexaose molecule was bound across the catalytic site, showing that TpDex had six subsites (-4 to +2) in the catalytic cleft. Marked movement of the Trp-376 side-chain along with loop 6, which was the side wall component of the cleft at subsite +1, was observed to occupy subsite +1, indicating that it might expel the cleaved aglycone subsite after the hydrolysis reaction. Structural comparison with other mesophilic enzymes indicated that several structural features of TpDex, loop deletion, salt bridge and surface-exposed charged residue, may contribute to thermostability.

Crystal structure of thermophilic dextranase from Thermoanaerobacter pseudethanolicus.,Suzuki N, Kishine N, Fujimoto Z, Sakurai M, Momma M, Ko JA, Nam SH, Kimura A, Kim YM J Biochem. 2016 Mar;159(3):331-9. doi: 10.1093/jb/mvv104. Epub 2015 Oct 21. PMID:26494689^[1]

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