Sidorov Roman A, Shashkov Alexander S, Solovyev Pavel A, Gorshkova Elena N, Tsydendambaev Vladimir D
Laboratory of Lipid metabolism, K.A. Timiryazev Institute of Plant Physiology, Russian Academy of Sciences, Moscow, Russia, 127276.
N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, Russia, 119991.
Lipids. 2018 Apr;53(4):437-445. doi: 10.1002/lipd.12025. Epub 2018 May 2.
Asymmetric, optically active sn-1,2-diacyl-3-acetyl-glycerols (AcDAG) have been known to scientists for several decades. However, to date, the problem of their structure has not been definitely resolved, which has led to a vast diversity of terms used for their designation in the literature. Using two-dimensional nuclear magnetic resonance, we have investigated AcDAG from the mature seeds of Euonymus maximowiczianus, from which we have been able to both identify a correlation of the methyl group in acetic acid residue with protons at the carbon atom at sn-3 position in the glycerol residue of the AcDAG molecule and, for the first time, demonstrate that this correlation is observed exclusively with one carbon atom at the α-position, but not with two as would have been expected in case of a racemic mixture. Moreover, results of our analysis of AcDAG isolated from the seeds of E. maximowiczianus directly confirm that diacylglycerol-3-acetyl-transferase is responsible for their biosynthesis, which reveals a strict specificity not only to acetyl-CoA as one of the substrates but also to the sn-3-position of the glycerol residue in sn-1,2-diacylglycerol during their biosynthesis.
不对称、具有旋光活性的sn-1,2-二酰基-3-乙酰甘油（AcDAG）已被科学家们知晓数十年。然而，迄今为止，其结构问题尚未得到明确解决，这导致文献中用于指代它们的术语种类繁多。利用二维核磁共振技术，我们研究了卫矛成熟种子中的AcDAG，从中我们既能确定乙酸残基中的甲基与AcDAG分子甘油残基sn-3位碳原子上的质子之间的相关性，又首次证明这种相关性仅在α位的一个碳原子上观察到，而不是像外消旋混合物那样在两个碳原子上观察到。此外，我们对从卫矛种子中分离出的AcDAG的分析结果直接证实，二酰甘油-3-乙酰转移酶负责它们的生物合成，这揭示了在其生物合成过程中，不仅对作为底物之一的乙酰辅酶A具有严格的特异性，而且对sn-1,2-二酰甘油中甘油残基的sn-3位也具有严格的特异性。
