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Publication Abstract from PubMed

A novel transketolase has been reconstituted from two separate polypeptide chains encoded by a 'split-gene' identified in the genome of the hyperthermophilic bacterium, Carboxydothermus hydrogenoformans. The reconstituted active alpha2beta2 tetrameric enzyme has been biochemically characterized and its activity has been determined using a range of aldehydes including glycolaldehyde, phenylacetaldehyde and cyclohexanecarboxaldehyde as the ketol acceptor and hydroxypyruvate as the donor. This reaction proceeds to near 100% completion due to the release of the product carbon dioxide and can be used for the synthesis of a range of sugars of interest to the pharmaceutical industry. This novel reconstituted transketolase is thermally stable with no loss of activity after incubation for 1 h at 70 degrees C and is stable after 1 h incubation with 50% of the organic solvents methanol, ethanol, isopropanol, DMSO, acetonitrile and acetone. The X-ray structure of the holo reconstituted alpha2beta2 tetrameric transketolase has been determined to 1.4 A resolution. In addition, the structure of an inactive tetrameric beta4 protein has been determined to 1.9 A resolution. The structure of the active reconstituted alpha2beta2 enzyme has been compared to the structures of related enzymes; the E1 component of the pyruvate dehydrogenase complex and D-xylulose-5-phosphate synthase, in an attempt to rationalize differences in structure and substrate specificity between these enzymes. This is the first example of a reconstituted 'split-gene' transketolase to be biochemically and structurally characterized allowing its potential for industrial biocatalysis to be evaluated.

A 'Split-Gene' Transketolase From the Hyper-Thermophilic Bacterium Carboxydothermus hydrogenoformans: Structure and Biochemical Characterization.,James P, Isupov MN, De Rose SA, Sayer C, Cole IS, Littlechild JA Front Microbiol. 2020 Oct 30;11:592353. doi: 10.3389/fmicb.2020.592353., eCollection 2020. PMID:33193259^[1]

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