Accurate molecular mass determination of mycolic acids by MALDI-TOF mass spectrometry
Accurate molecular mass determination of mycolic acids by MALDI-TOF mass spectrometry
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DOI：
10.1021/ac0105181
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发表时间：
2001-09-15
影响因子：
7.4
通讯作者：
Daffé, M
中科院分区：
文献类型：
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作者：
Laval, F;Lanéelle, MA;Daffé, M
利用基质辅助激光解吸电离飞行时间(MALDI-TOF)质谱仪，首次对分枝杆菌细胞膜中主要和特定的长链脂肪酸(C70-C90)组成的霉菌酸进行了分析。以2，5-DHB为基质分析了典型分枝杆菌菌剂的各种类型的纯化产物，因为少于10pmoL的分枝杆菌化合物足以获得完全由伪分子[M+Na](+)离子组成的分辨良好的质谱图，该结构与应用于这些分子的化学分析技术推导的结构一致。对MALDI质谱图的检测表明，各种分枝杆菌的链长与分枝杆菌菌株的生长速度有关。尽管生长缓慢的细菌，如结核分枝杆菌和溃疡分枝杆菌，会产生一系列奇数碳数(C74-C82)的α-霉菌酸，但快速生长细菌会合成奇数碳数和偶数碳数。此外，来自慢速生长的含氧真菌酸的主链比相应的α-真菌酸长4到6个碳原子，而快速生长的真菌酸精制的含氧同系物具有与其α-真菌酸相同的链长。此外，用MALDI质谱仪对结核分枝杆菌野生型菌株及其同基因突变株的粗脂肪酸混合物合成含氧菌酯的影响进行了比较分析，揭示了两株菌株的α-菌酯之间的结构差异。因此，该技术不仅提供了准确的分子质量和新的结构信息，而且还减少了样品消耗和节省了时间，因此似乎是一种快速和高灵敏度的真菌酸分析技术。
Mycolic acids, major and specific long-chain fatty (C70-C90) acid components of the mycobacterial cell envelope, were analyzed for the first time using matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry operating in a reflectron mode. The various types of purified mycolates from representative mycobacterial species were analyzed using 2,5-DHB as matrix, because less than 10 pmol of mycolates was sufficient to obtain well-resolved mass spectra composed exclusively of pseudomolecular [M + Na](+) ions consistent with the structures deduced from the chemical analytical techniques applied to these molecules. Examination of the MALDI mass spectra demonstrated that the chain lengths of the various mycolates correlated with the growth rate of mycobacterial strains. Although slow growers, such as Mycobacterium tuberculosis and Mycobacterium ulcerans, produced a series of odd carbon numbers (C74-C82) of alpha -mycolic acids, rapid growers synthesized both odd and even carbon numbers. In addition, the main chain of oxygenated mycolic acids from slow growers were four to six carbon atoms longer than the corresponding alpha -mycolic acids, whereas rapid growers elaborated oxygenated homologues possessing the same chain lengths as their alpha -mycolic acids. Furthermore, a comparative analysis of the crude fatty acid mixtures from a wild-type strain of M. tuberculosis and its isogenic mutant effected in the synthesis of oxygenated mycolates by MALDI mass spectrometry revealed structural differences between the alpha -mycolates from the two strains. Thus, this technique appeared to be a rapid and highly sensitive technique for the analysis of mycolic acids, not only by providing accurate molecular masses and new structural information, but also by both reducing sample consumption and saving time.