15 research outputs found
Molecular characterization of a human G20P[28] rotavirus a strain with multiple genes related to bat rotaviruses
Group A rotaviruses are the major cause of severe gastroenteritis in the young of mammals and birds. This report describes characterization of an unusual G20P[28] rotavirus strain detected in a 24 month old child from Suriname. Genomic sequence analyses revealed that the genotype constellation of the Suriname strain RVA/Human-wt/SUR/2014735512/2013/G20P[28] was G20-P[28]-I13-R13-C13-M12-A23-N13-T15-E20-H15. Genes VP1, VP2, VP3, NSP1, NSP2, NSP3, NSP4 and NSP5 were recently assigned novel genotypes by the Rotavirus Classification Working Group (RCWG). Three of the 11 gene segments (VP7, VP4, VP6) were similar to cognate gene sequences of bat-like human rotavirus strain Ecu534 from Ecuador and the VP7, NSP3 and NSP5 gene segments of strain RVA/Human-wt/SUR/2014735512/2013/G20P[28] were found to be closely related to gene sequences of bat rotavirus strain 3081/BRA detected in Brazil. Although distantly related, the VP1 gene of the study strain and bat strain BatLi09 detected in Cameroon in 2014 are monophyletic. The NSP1 gene was found to be most closely related to human strain QUI-35-F5 from Brazil. These findings suggest that strain RVA/Human-wt/SUR/2014735512/2013/G20P[28] represents a zoonotic infection from a bat host
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Hydride transfer made easy in the oxidation of alcohols catalyzed by choline oxidase
Choline oxidase (E.C. 1.1.3.17) catalyzes the two-step, four-electron oxidation of choline to glycine betaine with betaine aldehyde as enzyme-associated intermediate and molecular oxygen as final electron acceptor (Scheme 1). The gem-diol, hydrated species of the aldehyde intermediate of the reaction acts as substrate for aldehyde oxidation, suggesting that the enzyme may use similar strategies for the oxidation of the alcohol substrate and aldehyde intermediate. The determination of the chemical mechanism for alcohol oxidation has emerged from biochemical, mechanistic, mutagenetic, and structural studies. As illustrated in the mechanism of Scheme 2, the alcohol substrate is initially activated in the active site of the enzyme by removal of the hydroxyl proton. The resulting alkoxide intermediate is then stabilized in the enzyme-substrate complex via electrostatic interactions with active site amino acid residues. Alcohol oxidation then occurs quantum mechanically via the transfer of the hydride ion from the activated substrate to the N(5) flavin locus. An essential requisite for this mechanism of alcohol oxidation is the high degree of preorganization of the activated enzyme-substrate complex, which is achieved through an internal equilibrium of the Michaelis complex occurring prior to, and independently from, the subsequent hydride transfer reaction. The experimental evidence that support the mechanism for alcohol oxidation shown in Scheme 2 is briefly summarized in the Results and Discussion section