A combination of two chromatographic and one enzymatic methods was used for identification of the molecular species of triacylglycerols (TAGs) from Streptomyces avermitilis. Streptomyces avermitliswas cultured on various carbon sources and the ratio of iso- (i-FAs), anteiso- (ai-FAs), and straight-chain- (n-FAs) fatty acids was modified by precursor-directed biosynthesis. Saturated TAGs were separated from other lipids (including TAGs containing unsaturated FAs) using Ag⁺ ion cartridges. Analysis of TAGs wereperformed by RP-HPLC/ESI⁺ tandem mass spectrometry. Both the synthetically prepared sn-TAGs and the natural mixture of TAGmolecular species of wereseparated and identified by tandem MS. The structures of synthetic TAGs werefurther confirmed by pancreatic lipase, which cleaves sn-TAGs into sn-2-monoacylglycerols. The retention times (tR) of the individual regioisomers and enantiomers were found to be depend on the structure of the TAGs. If one branched acyl (iso or anteiso) is present in the TAG molecule, then the elution order is enantiomer (n/n/br), opposite enantiomer (br/n/n), regioisomer (n/br/n). In the case where two branched acyls are in the TAG molecule, the order of the elution is different, that is, br/n/br, n/br/br, br/br/n. In all cases, it was further demonstrated that tandem MS of either synthetically prepared TAGs or TAGs obtained from natural material, that is, n-16:0/ai-15:0/n-16:0 and i-16:0/n-15:0/i-16:0 are identical. Unfortunately, it is not possible to distinguish by ESI⁺ tandem MS such TAGs, which differ only in the branching of the acyls. The results of our analyses of TAGs are in good agreement with previously published data in other streptomycetes.

中文翻译：

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分离含有支链脂肪酸（异和/或反异）的三酰基甘油的区域异构体和对映异构体

两种色谱法和一种酶法的组合用于鉴定来自阿维链霉菌的三酰基甘油 (TAG) 的分子种类。Streptomyces avermitlis在各种碳源上培养，异-(i-FAs)、反异-(ai-FAs) 和直链-(n-FAs) 脂肪酸的比例通过前体定向生物合成进行了修改。^{使用 Ag +}离子盒将饱和 TAG 与其他脂质（包括含有不饱和 FA 的 TAG）分离。TAG的分析通过RP-HPLC/ESI ⁺串联质谱法进行。合成制备的sn-TAG和TAG分子种类的天然混合物通过串联MS分离和鉴定。合成 TAG 的结构进一步通过胰脂肪酶得到证实，该酶将sn -TAG 切割成sn -2-单酰基甘油。保留时间（tR) 的单个区域异构体和对映异构体被发现取决于 TAG 的结构。如果 TAG 分子中存在一个支链酰基（异或反异），则洗脱顺序为对映异构体 (n/n/br)、相反对映异构体 (br/n/n)、区域异构体 (n/br/n)。在TAG分子中有两个支链酰基的情况下，洗脱顺序不同，即br/n/br、n/br/br、br/br/n。在所有情况下，进一步证明了合成制备的 TAG 或从天然材料获得的 TAG 的串联 MS，即 n-16:0/ai-15:0/n-16:0 和 i-16:0/ n-15:0/i-16:0 是相同的。不幸的是，无法通过 ESI ^{+进行区分}串联 MS 这样的 TAG，其不同之处仅在于酰基的支化。我们对 TAG 的分析结果与之前在其他链霉菌中公布的数据非常一致。