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101.
102.
Beta-lactamases have been reported to be largely responsible for beta-lactam resistance in Mycobacteria. We report the characterization of a cell-associated beta-lactamase from Mycobacterium smegmatis. The enzyme hydrolyzed the "beta-lactamase-stable" oximinocephalosporins. Nitrocefin was the best substrate. 6-Beta-iodopenicillanate, clavulanate and sulbactam were effective inhibitors, whereas the Ki value for aztreonam was high. From its substrate and inhibitor profile, the enzyme appeared to be a cephalosporinase of group 2e. 相似文献
103.
HY Song CH Régnier CJ Kirschning DV Goeddel M Rothe 《Canadian Metallurgical Quarterly》1997,94(18):9792-9796
104.
A gene encoding a bifunctional homodimeric dihydrofolate reductase-
thymidylate synthase (DHFR-TS) was constructed by destroying the stop codon
of Escherichia coli dihydrofolate reductase (DHFR) and joining the coding
sequences of the monofunctional enzymes by a five amino acid linker. The
protein was designed to mimic features of active site proximity and
electrostatics in the protozoan DHFR-TSs which are believed to be important
in channeling of the DHFR substrate, H2folate, to TS. The genetically
engineered catalytically active homodimeric bifunctional DHFR-TS was
expressed, purified and characterized. The component activities of the
purified bifunctional enzyme had kinetic properties similar to those of the
monofunctional TS and DHFR, but unlike the authentic bifunctional enzymes
from protozoa this enzyme did not kinetically channel dihydrofolate from
DHFR to TS.
相似文献
105.
佳能针对家居、商务、旅游、摄影爱好等不同消费群,推出了ZR 60、ZR65MC、ZR 70MC、ELURA 50MC以及OPTURA 10/20等六款全新数码摄像机,让你随时记录生活点滴,回味快乐时光。佳能新一代数码摄像机具有突破性的设计,流线动感的外型,包覆铝镁合金机身,采用了Canon引以为傲的二 相似文献
106.
Recent evidence suggests that conservative elites' claims of a liberal media are having an impact upon public perceptions of news coverage. With this in mind, we examined two related questions in the context of the 1988, 1992, and 1996 presidential elections. First, what factors may be prompting conservative elites to make allegations of liberal media bias? Second, what factors may influence when news media report these criticisms during presidential campaigns? Findings suggest that these criticisms of news media are at least partly strategic and reflect a dynamic relationship between political elites and journalists during a presidential campaign. 相似文献
107.
108.
LC Lastoria DV Opromolla RN Fleury F Habermann PR Curi 《Canadian Metallurgical Quarterly》1998,66(2):190-200
The authors studied the Mitsuda reaction in 37 leprosy patients (18 reactional tuberculoid, 19 reactional borderline cases) and compared the results with clinical findings, histopathology and bacilloscopy. Evaluation of the Mitsuda reaction was carried out on days 30, 60, 90 and 120. Most of the reactional tuberculoid patients showed a Mitsuda reaction of +3 in opposition to the reactional borderline patients who showed only +. Bacilloscopic analysis revealed that in 75% of the reactional tuberculoid cases there were rare or no bacilli; bacilli were present in 95% of the reactional borderline cases. The authors conclude that reactional tuberculoid cases have a greater ability to clear bacilli than reactional borderline cases, and that the Mitsuda reaction is a useful tool for the differentiation between these two types of leprosy. 相似文献
109.
110.