Mass spectrometric analysis of O-peracetylated derivatives of 1-monomycoloylglycerol isolated from Corynebacterium pseudotuberculosis, Rhodococcus rhodochrous and R. lentifragmentus.
1-Monomycoloylglycerols from Corynebacterium pseudotuberculosis, Rhodococcus rhodochrous and R. lentifragmentus were reacted with acetic acid ahydride in the presence of pyridine. On infrared spectra the reaction products showed a sharp characteristic absorption of the acetyl ester group at 1235 cm-1; the hydroxyl group absorption (3400 cm-1) was absent. O-Peracetylated monomycoloylglycerols were analyzed by mass spectrometry under electron impact mode. The most common and representative peaks were associated to the following remarkable fragments: (a) peak at m/z 159 represented the backbone of the glycerol unit of peracetylated monomycoloylglycerols; it constituted the diagnostic and base peak of that group of compounds; (b) peak representing the glycerol moiety together with the alpha-subunit of the mycolic acid moiety; it gave the size of the chain length of the hydrocarbon side chain of that mycolic acid; and (c) a series of peaks of acylium ions minus 60 mass units (acetic acid) indicated the size of the chain length of the esterified mycolic acid. Therefore, acetylation of monomycoloylglycerol becomes the derivatized compound suitable for mass spectrometry. Moreover, the derivatives are more thermostable and resistant to pyrolysis. By associating these properties, separation and identification of homologs of monomycoloylglycerols are further expected.
Ioneda
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Universidade de São Paulo, Instituto de Química B9T, Brazil.
D003352:Corynebacterium / Q000032:analysis*; D013058:Mass Spectrometry; D009171:Mycolic Acids / Q000032:analysis* / Q000737:chemistry; D012240:Rhodococcus / Q000032:analysis*; D014280:Triglycerides / Q000032:analysis* / Q000737:chemistry
D009171:Mycolic Acids; C066432:O-peracetylmonomycoloylglycerol; D014280:Triglycerides