Analysis, distribution and function of unnatural glycerophospholipids in marine organisms

本研究的目的是阐明不寻常的甘油磷脂和糖脂在海洋生物中的分布和生理功能。为此，采用手性相、反相和反相高效液相色谱与电喷雾电离质谱仪(ESI-MS)相结合的方法分离和鉴定甘油酯的立体异构体和区域异构体。利用这些技术，我们从包括海洋细菌在内的各种微生物中发现了一种非天然的磷脂酰甘油(1，2-diacyl-sn-glycero-3-phospho-3‘-sn-glycerol，R，R构型)。R、R异构体含量随着培养温度的升高而增加。结果表明，细菌不仅通过改变磷脂酰甘油的不饱和度，而且通过改变磷脂酰甘油的立体异构体组成来适应温度。在本研究中，我们还对甘油磷脂…的反向异构体进行了分离和鉴定。反相高效液相色谱-电喷雾电喷雾质谱分离得到较多的DS(PtdCho、PtdEtn、PtdIno)和甘油酯(MGDG、DGDG、SQDG)。这些甘油脂被层析为从母体分子衍生的1，2-二酰基-SN-甘油的完整形式或3，5-二硝基苯基氨酯。在高效的C18色谱柱上，对非常不同的酰基对的反相异构体，如20：5-16：0和22：6-16：0，获得了很好的拆分。用该方法对几种鱼类和海藻的甘油脂进行了分析，发现只有条斑紫菜和江豚等海洋红藻的甘油酯有两个清晰可分辨的峰，分别为20：5(sn-1)/16：0(sn-2)和16：0(sn-1)/20：5(sn-2)和20：4(sn-1)/16：0(sn-2)和16：0(sn-1)/20：5(sn-2)。本方法首次直接证明了天然甘油三脂中存在反向异构体，有助于促进红藻中反向异构体的生物合成途径和生理意义的研究。较少

The aim of this study was to clarify the distribution and physiological function of unusual glycerophospho- and glycolipids in marine organisms. For this purpose, chiral phase HPLC, reversed-phase HPLC and reversed-phase HPLC in conjunction with electrospray ionization mass spectrometry(ESI-MS) were applied to the separation and identification of stereoisomeric and regio-isomeric glycerolipids. Using these techniques, we found an unnatural phosphatidylglycerol (1,2-diacyl-sn-glycero-3-phospho-3'-sn-glycerol, R, R configurations at the two chiral centers) from various kinds of microorganisms including marine bacteria. The R, R isomer content increased with increasing culture temperature. The results strongly suggest that the bacteria adapt to temperature by alternating not only the degree of unsaturation but also the stereoisomer composition of phosphatidylglycerols. In the present study, we also investigated the separation and identification of the reverse isomers of glycerophospholipi … More ds (PtdCho,PtdEtn,PtdIno) and glycoglycerolipids (MGDG,DGDG,SQDG) by reversed-phase HPLC/ESI-MS. These glycerolipids were chromatographed as intact forms or 3,5-dinitrophenylurethanes of the 1,2-diacyl-sn-glycerols derived from the parent molecules. Excellent resolution was achieved for reverse isomers of very different pairs of acyl groups, such as 20:5-16:0 and 22:6-16:0, on highly efficient C18 columns. Using the method, we analyzed the glycerolipids from some fish and marine algae, and found that only MGDG from marine red algae, such as Porphyra yezoensis and Gracilaria verrucosa, gave two clearly resolved peaks, representing the reverse isomers of 20:5(sn-1)/16:0(sn-2) and 16:0(sn-1)/20:5(sn-2), and 20:4(sn-1)/16:0(sn-2) and 16:0(sn-1)/20:5(sn-2), respectively. The present method provides the first direct demonstration of the occurrence of reverse isomers in natural glycoglycerolipids and should be helpful in promoting work on the biosynthetic pathway and physiological importance of the reverse isomers in the red algae. Less