BORONIC ACID INHIBITORS OF BETA-LACTAMASES

在我们的初步研究中，我的团队收集了大肠杆菌的动力学数据 RTEM-2β-内酰胺酶。这样做是为了了解这种机制。 这种酶的作用。 我们研究了这种A类B-内酰胺酶的底物专一性。 两种头孢菌素类药物PADAC和Nitrocefin。我们发现了 游离酶上的必需基团的pKs分别为5.5和7.5。这些 PKS暂时归属于活性基团Glu-166和Lys-73。PK2 被底物结合所改变，而pK1不变。 硼酸对大肠杆菌RTEM-2β-内酰胺酶的抑制作用较快， 在混合后的一分钟内发生的。在测试的硼酸中， 具有大体积疏水取代基的芳基硼酸是最有效的 抑制剂。在其他取代的苯硼酸中，那些 吸电子取代基是较好的缓蚀剂。PH依赖关系 对这组化合物的抑制作用显示出碱性的电离 群的PK约为5.3。PK2反映了细胞的电离 取代苯硼酸。 在这项提案中，我建议让MBR的学生有机会 制备一对潜在的B-过渡态类似物抑制剂 内酰胺酶，一种硼酸和一种类似的醛。硼酸有 L-已经被证明是很好的缓蚀剂；对于醛，情况是 不太清楚。一种特定的醛应该能澄清醛是否能抑制 这些丝氨酸酶和丝氨酸蛋白酶一样。另外，一种特殊的硼酸 酸性抑制剂可以帮助阐明或观察酶的作用机制。

In our preliminary studies, my group has collected kinetic data for E. coli RTEM-2 Beta-lactamase. This was done in order to understand the mechanism of action of this enzyme. We studied the substrate specificity of this Class A B-lactamase for the two cephalosporins PADAC and nitrocefin. We found the presence of essential groups on the free enzyme which have pKs of 5.5 and 7.5. These pKs are tentatively assigned to the active groups Glu-166 and Lys-73. pK2 was shifted by substrate binding, while pK1 was unchanged. Inhibition of E. coli RTEM-2 B-lactamase by boronic acids was rapid, occurring within a minute of mixing. Of the tested boronic acids, the arylboronic acids with bulky hydrophobic substituents were the most potent inhibitors. Of the other substituted benzeneboronic acids, those with electron-withdrawing substituents wee better inhibitors. The pH-dependence of inhibition for this group of compounds showed the ionization of a basic group with a pK of about 5.3. pK2 reflected the ionization of the substituted benzeneboronic acid. In this proposal, I propose to give MBRS students the opportunity to prepare a potential pair of transition state analog inhibitors of the B- lactamases, a boronic acid and an analogous aldehyde. Boronic acids have l-already been shown to be good inhibitors; with aldehydes the picture is less clear. A specific aldehyde should clarify if aldehydes can inhibit these serine enzymes as they do serine proteases. Also, A specific boronic acid inhibitor can help clarify or view of the enzyme's mechanism.