Bongaerts G P, Molendijk L
Antimicrob Agents Chemother. 1984 Feb;25(2):234-7. doi: 10.1128/AAC.25.2.234.
The relationship between plasmid-coded aminoglycoside 2"-O-nucleotidyltransferase [ANT(2")] activity and the minimum inhibitory concentration for aminoglycosides was studied. ANT(2") was very unstable, and therefore, procedures for handling this enzyme were optimized. Escherichia coli L58058.1 producing ANT(2") was resistant to gentamicin, sisomicin, kanamycin, tobramycin, and dibekacin but susceptible to netilmicin, amikacin, and neomycin. However, only amikacin and neomycin were not modified by ANT(2"). A correlation between the substrate profile of the enzyme tested at 0.15 mM and the minimum inhibitory concentrations of the aminoglycosides could not be demonstrated. The substrate concentration-dependent enzyme activity curves proved to be a better alternative than a substrate profile based on tests at one concentration. At concentrations of greater than 10(-2) mM, ANT(2") demonstrated substrate inhibition that explains the discrepancy between ANT(2") activity and the minimum inhibitory concentrations. A close correlation was found between the physiological efficiency (Vmax/Km ratio) of ANT(2") and the minimum inhibitory concentrations for the enzyme-producing strain.
研究了质粒编码的氨基糖苷2”-O-核苷酸转移酶[ANT(2”)]活性与氨基糖苷类药物最低抑菌浓度之间的关系。ANT(2”)非常不稳定，因此，对处理该酶的程序进行了优化。产生ANT(2”)的大肠杆菌L58058.1对庆大霉素、西索米星、卡那霉素、妥布霉素和地贝卡星耐药，但对奈替米星、阿米卡星和新霉素敏感。然而，只有阿米卡星和新霉素未被ANT(2”)修饰。在0.15 mM下测试的该酶底物谱与氨基糖苷类药物最低抑菌浓度之间未显示出相关性。底物浓度依赖性酶活性曲线被证明是比基于单一浓度测试的底物谱更好的选择。在浓度大于10(-2) mM时，ANT(2”)表现出底物抑制，这解释了ANT(2”)活性与最低抑菌浓度之间的差异。发现ANT(2”)的生理效率（Vmax/Km比值）与产酶菌株的最低抑菌浓度之间存在密切相关性。
