PENICILLIN-BINDING SITE ON THE ESCHERICHIA-COLI CELL-ENVELOPE
PENICILLIN-BINDING SITE ON THE ESCHERICHIA-COLI CELL-ENVELOPE
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DOI：
10.1128/jb.167.2.492-495.1986
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发表时间：
1986-08-01
影响因子：
3.2
通讯作者：
LORIAN, V
中科院分区：
文献类型：
--
作者：
AMARAL, L;LEE, Y;LORIAN, V
研究了35s标记的青霉素在不同ph值（4 ~ 11）范围内与大肠杆菌超声检测获得的“细胞包膜”中不同的青霉素结合蛋白（PBPs）的结合。在低pH下，PBPs、1b、1c、2和3显示出最大的结合量。在高pH下，这些PBPs结合的青霉素最少。PBPs 1a和5/6在pH值为10时结合量最大，在pH值为4时结合量最小。除PBP 5/6外，pH对青霉素的结合有直接影响。将pH对PBP 5/6与青霉素结合的影响与对β -内酰胺酶活性的影响区分开来的实验表明，尽管在最低pH时发生了实质性的结合(4)，但结合量随着pH的增加而增加，在pH 10时达到最大值。根据早期的研究，提出在高pH下的结合涉及青霉素的C-7和PBPs的游离epsilon氨基之间形成共价键。在ph值从4到8的范围内，青霉素的1号位置被硫占据，被认为是与PBP 5的巯基建立共价键的位置。对游离epsilon氨基或巯基的特异性阻滞剂的使用表明，无论PBP 5的存在对青霉素的结合影响很小或没有影响，两者的存在都完全阻止了青霉素的结合。丝氨酸羟基的特异性阻滞剂不影响青霉素的结合。这些观察结果表明，青霉素分子在1号位置的S和PBP 5的巯基之间以及PBP 5的C-7和游离的ε -氨基之间形成同步键。
The binding of 35S-labeled penicillin to distinct penicillin-binding proteins (PBPs) of the "cell envelope" obtained from the sonication of Escherichia coli was studied at different pHs ranging from 4 to 11. At low pH, PBPs, 1b, 1c, 2, and 3 demonstrated the greatest amount of binding. At high pH, these PBPs bound the least amount of penicillin. PBPs 1a and 5/6 exhibited the greatest amount of binding at pH 10 and the least amount at pH 4. With the exception of PBP 5/6, the effect of pH on the binding of penicillin was direct. Experiments distinguishing the effect of pH on penicillin binding by PBP 5/6 from its effect on beta-lactamase activity indicated that although substantial binding occurred at the lowest pH (4), the amount of binding increased with pH, reaching a maximum at pH 10. Based on earlier studies, it is proposed that the binding at high pH involves the formation of a covalent bond between the C-7 of penicillin and free epsilon amino groups of the PBPs. At pHs ranging from 4 to 8, position 1 of penicillin, occupied by sulfur, is considered to be the site that establishes a covalent bond with the sulfhydryl groups of PBP 5. The use of specific blockers of free epsilon amino groups or sulfhydryl groups indicated that wherever the presence of each had little or no effect on the binding of penicillin by PBP 5, the presence of both completely prevented binding. The specific blocker of the hydroxyl group of serine did not affect the binding of penicillin. These observations suggest that a molecule of penicillin forms simultaneous bonds between its S at position 1 and sulfhydryl groups of PBP 5 and between its C-7 and free epsilon amino groups of PBP 5.