Sulbactam形式只有少量的不可逆acrylate-enzyme SHV-1 beta-lactamase。

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Totir马女士希尔芬迪,凯里MP,谢,Buynak JD, Bonomo RA,凯里公关

Sulbactam形式只有少量的不可逆acrylate-enzyme SHV-1 beta-lactamase。

生物化学。2007年8月7日,46 (31):8980 - 7。Epub 2007年7月13日。

PubMed ID
17630699 (在PubMed
]
文摘

Sulbactam是一个系统,即beta-lactamase酶的抑制剂在临床实践中使用。它经历了一系列复杂的化学反应的活性部位已经被广泛的研究在过去的三十年。然而,实际的物种产生抑制作用在临床环境尚未建立。最近我们组的研究,利用拉曼显微镜和x射线晶体学,发现大量enamine-based酰基酶物种存在几分钟的单晶SHV-1 beta-lactamases可导致显著的抑制作用。的烯胺是由分解形成循环beta-lactam结构进一步转换导致亚胺的形成和随后的异构化顺式或反式烯胺。另一个受欢迎的形式的抑制起源于第二次亲核攻击亚胺氨基酸侧链,例如,从丝氨酸130年,形成交联的物种在活动网站,可以降低acrylate-like物种不可逆转地绑定到酶。因此,亚胺是一个分支点的反应途径。使用sulbactam和6,6-dideuterated sulbactam我们遵循这些WT的替代途径,E166A SHV-1 beta-lactamase通过拉曼显微研究单一酶晶体。无标号sulbactam,拉曼数据显示一个acrylate-like物种的存在,可能3-serine丙烯酸酯,反应开始后的几个小时的晶体。然而,6,6-dideutero模拟丙烯酸酯的签名出现在几分钟的时间尺度。 The Raman signatures, principally an intense feature near 1530 cm-1, are assigned based on quantum mechanical calculations on model compounds that mimic acrylate species in the active site. The different time scales observed for acrylate-like product formation are ascribed to different rates of reaction involving the imine intermediate. It is proposed that for the unsubstituted sulbactam the conversion from imine to enamine, which involves breaking a C-H bond, is aided by quantum mechanical tunneling. For the 6,6-dideutero-sulbactam the same step involves breaking a C-D bond, which has little or no assistance from tunneling. Consequently the conversion to enamines is slower, and a higher population of imine results, presenting the opportunity for the competing reaction with the second nucleophile, serine 130 being the prime candidate. The hydrolysis of the resulting cross-linked intermediate leads to the observed rapid buildup of the acrylate product in the Raman spectra from the dideutero analogue. The protocol used here, essentially running the reactions with the two forms of sulbactam in parallel, provides an element of control and enables us to conclude that, for the unsubstituted sulbactam, the formation of the cross-linked intermediate and the final irreversible acrylate product is not a significant route to inhibition of SHV-1.

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药物
药物靶点
药物 目标 类 生物 药理作用 行动
Sulbactam Beta-lactamase 蛋白质 金黄色葡萄球菌
是的
抑制剂
 细节