Heck A J, Bonnici P J, Breukink E, Morris D, Wills M
Department of Biomolecular Mass Spectrometry, Bijvoet Center for Biomolecular Research and Utrecht Institute for Pharmaceutical Sciences, Utrecht University, The Netherlands.
Chemistry. 2001;7(4):910-6. doi: 10.1002/1521-3765(20010216)7:4<910::aid-chem910>3.0.co;2-u.
It is shown that several vancomycin group antibiotics (vancomycin, eremomycin, and avoparcin) undergo spontaneous chemical modifications when kept at room temperature at neutral pH in aqueous solutions containing traces of formaldehyde or acetaldehyde. This chemical modification predominantly results in a mass increase of 12 Da in the reaction with formaldehyde and 26 Da in the case of acetaldehyde. By using tandem mass spectrometry the modification can unambiguously be identified as originating from the formation of a ring-closed 4-imidazolidinone moiety at the N-terminus of the glycopeptide antibiotics, that is, near the receptor binding pocket of the glycopeptide antibiotics. Bioaffinity mass spectrometry shows that this ring-closure results in a dramatically decreased affinity for the peptidoglycan-mimicking D-alanyl-D-alanine receptor. Additionally, in vitro inhibition measurements on two different strains of bacteria have revealed that the modified antibiotics display reduced antibacterial activity. The ring-closure is also shown to have a dissociative effect on the dimerization of the vancomycin-analogue eremomycin. The spontaneous reaction of vancomycin with formaldehyde or acetaldehyde may have implications not only for the clinical use of this class of antibiotics, but also for the effectiveness of these antibiotics when they are used in chiral separation chromatography or capillary electrophoresis.
结果表明，几种万古霉素类抗生素（万古霉素、埃瑞霉素和阿伏帕星）在室温下、中性pH值、含有痕量甲醛或乙醛的水溶液中会发生自发化学修饰。这种化学修饰主要导致与甲醛反应时质量增加12 Da，与乙醛反应时质量增加26 Da。通过串联质谱法，这种修饰可以明确鉴定为糖肽抗生素N端形成了一个闭环4-咪唑烷酮部分，即靠近糖肽抗生素的受体结合口袋处。生物亲和质谱显示，这种环化导致对模拟肽聚糖的D-丙氨酰-D-丙氨酸受体的亲和力显著降低。此外，对两种不同细菌菌株的体外抑制测量表明，修饰后的抗生素抗菌活性降低。环化还显示对万古霉素类似物埃瑞霉素的二聚化有解离作用。万古霉素与甲醛或乙醛的自发反应不仅可能对这类抗生素的临床应用有影响，而且对它们在手性分离色谱或毛细管电泳中的有效性也有影响。
