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61.
Incubation of [14C] caffeine with hepatic microsomes from male AKR/J mice resulted in the formation of several metabolites including 1, 3, 7-trimethylurate and 6-amino-5-(N-formylmethyl-amino)-1, 3-dimethyluracil. These two compounds comprised about 60% of products and are major urinary metabolites in several animals. When cytosol was included during incubation, there was a 14-fold increase in yield of the uracil at the expense of the urate; the combination of the two metabolites remained about 60% of total products. Cytosol alone was catalytically inert. Glutathione and other sulfhydryl compounds reproduced the effect of cytosol, and the action of cytosol was accounted for quantitatively by its sulfhydryl content. We propose that an oxidized intermediate of caffeine en route to trimethylurate is reduced by glutathione to the ring-opened uracil derivative. 相似文献
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Michitaro Nagasawa James Amigo Chan Charles J. Sih 《Prostaglandins & other lipid mediators》1974,8(3):221-230
Prostaglandins E1, F1α and A2 were covalently joined to the surface of Sepharose as carboxamide linkages. The insolubilized prostaglandins were shown to function effectively in the purification of 15(S) -hydroxyprostaglandin dehydrogenase. 相似文献
64.
Serotyping is the foundation of pathogenic Escherichia coli diagnostics; however, few laboratories have this capacity. We developed a molecular serotyping protocol that targets, genetically, the same somatic and flagellar antigens of E. coli O26:H11 used in traditional serotyping. It correctly serotypes strains untypeable by traditional methods, affording primary laboratories serotyping capabilities. 相似文献
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E. coli cells containing a temperature-sensitivednaE mutation, in the α-subunit of holoenzyme DNA polymerase III, do not survive at the restrictive temperature. Such cells may
survive in the presence of thepcbA1 mutation, an allele of thegyrB gene. Such survival is dependent on an active DNA polymerase I. Evidence indicates that DNA polymerase I interacts directly
in the replisome (REP·A). Despite normal survival for cells using thepcbA replication pathway after some type of DNA damage, we have noted a failure of damage-induced mutagenesis. Here we present
evidence supporting a model of replisome pausing in cells dependent upon thepcbA replication pathway. The model argues that the (REP·A) complex pauses longer at the site of the lesion, allowing excision
repair to occur completely. In the normal replication pathway (REP·E) bypass of the lesion occurs, fixing the mutation. 相似文献
68.
Summary The kinetics of thermal deactivation for thermostable DNA polymerase enzymes were investigated by using the experimental data published elsewhere (Nielson et al. 1996. Strategies. 9, 7–8). The order of deactivation (a) and the deactivation rate constants (k
d) were determined for different Taq DNA polymerase enzymes and were found to be of first order. 相似文献
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