Bulloch Esther M M, Jones Michelle A, Parker Emily J, Osborne Andrew P, Stephens Elaine, Davies Gareth M, Coggins John R, Abell Chris
Department of Chemistry, University of Cambridge, University Chemical Laboratory, Lensfield Road, Cambridge CB2 1EW, UK.
J Am Chem Soc. 2004 Aug 18;126(32):9912-3. doi: 10.1021/ja048312f.
(6S)-6-Fluoroshikimate has antimicrobial activity. The molecular basis of this effect had not been identified, but there was speculation that (6S)-6-fluoroshikimate is first converted in vivo into 2-fluorochorismate, which then could inhibit 4-amino-4-deoxychorismate synthase (ADCS). 2-Fluorochorismate was prepared from E-fluorophosphoenolpyruvate and erythose-4-phosphate by the sequential reactions of DAHP synthase, dehydroquinate synthase, dehydroquinase, shikimate dehydrogenase, EPSP synthase, and chorismate synthase. Inhibition studies on ADCS showed that it was inhibited rapidly and irreversibly by 2-fluorochorismate. Electrospray mass spectrometry of the inactivated enzyme showed an additional mass of 198 +/- 10 Da. A novel peptide of 1087.6 Da was identified in the HPLC trace for the tryptic digest of 2-fluorochorismate-inactivated ADCS. Sequencing of this peptide by MS/MS showed that the peptide corresponded to residues 272-279 with a modification of 206.1 Da on Lys-274. This observation is particularly exciting in the context of a recent proposal for the catalytic mechanism of ADCS.
(6S)-6-氟莽草酸具有抗菌活性。这种效应的分子基础尚未确定，但有人推测(6S)-6-氟莽草酸在体内首先转化为2-氟分支酸，然后它可能抑制4-氨基-4-脱氧分支酸合酶（ADCS）。2-氟分支酸由E-氟磷酸烯醇丙酮酸和赤藓糖-4-磷酸通过DAHP合酶、脱氢奎尼酸合酶、脱氢奎尼酸酶、莽草酸脱氢酶、EPSP合酶和分支酸合酶的连续反应制备而成。对ADCS的抑制研究表明，它被2-氟分支酸快速且不可逆地抑制。失活酶的电喷雾质谱显示额外增加了198±10 Da的质量。在2-氟分支酸失活的ADCS的胰蛋白酶消化产物的HPLC图谱中鉴定出一种1087.6 Da的新肽段。通过串联质谱对该肽段进行测序表明，该肽段对应于272-279位残基，且在274位赖氨酸上有206.1 Da的修饰。在最近关于ADCS催化机制的提议背景下，这一观察结果特别令人兴奋。
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