BORONIC ACID INHIBITORS OF BETA-LACTAMASES

在我们的初步研究中，我的小组收集了E.杆菌 RTEM-2 β-内酰胺酶。 这样做是为了了解机制 这种酶的作用。 我们研究了这种A类B-内酰胺酶对大肠杆菌的底物特异性， 两种头孢菌素PADAC和硝头孢菌素。 我们发现了 游离酶上pK为5.5和7.5的必需基团。 这些 pK暂时归属于活性基团Glu-166和Lys-73。 PK2 通过底物结合转移，而pK 1不变。 对E. coliRTEM-2B-内酰胺酶酶解速度快， 在混合的一分钟内发生。 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 抑制剂的 在其他取代的苯硼酸中，具有 吸电子取代基是较好的抑制剂。 pH依赖性 这组化合物的抑制作用显示了碱性离子的电离， pK约为5.3。pK 2反映了电离的 取代苯硼酸 在这个建议中，我建议给MBRS学生机会， 制备一对潜在的B-过渡态类似物抑制剂， 内酰胺酶、硼酸和类似醛。 硼酸具有 L-已被证明是良好的抑制剂;与醛的图片是 不太清楚。 一种特定的醛应该澄清醛是否可以抑制 这些丝氨酸酶和丝氨酸蛋白酶一样。 另外，一种特殊的硼 酸抑制剂有助于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.