CHARACTERIZATION OF PHOSPHATIDYLGLYCEROL IN PLANT CHLOROPLASTS BY

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 磷脂酰甘油(PG)是植物叶绿体的主要磷脂。拟南芥PG在主要18：3/D316：1-PG、18：2/D316：1-PG和16：0/D316：1-PG中都有一个不寻常的脂肪酰基链，3，4-反式-十六碳烯基(D316：1)位于sn-2位。当在串联四极杆或离子陷阱质谱仪中进行低能碰撞激活解离(CAD)时，含有D316：1-PG的PG分子的[M-H]离子给出的乘积离子光谱很容易与不含D316：1物种的PG产生的乘积离子光谱区分开来。含有D316：1-脂肪酸的PG通过MS2乘积-离子质谱图进行了表征，其中包含主要的[M-H-236]离子，这些离子是由于失去D316：1-脂肪酸取代基烯酮而产生的。这是由于烯酮损失中涉及的D316：1-脂肪酸取代基的-氢是非常不稳定的烯丙基氢。这导致了236的优先中性损失，并提供了一种灵敏的串联四极杆质谱学手段来鉴定脂质混合物中含有D316：1的PG物种。低能串联质谱学方法还允许揭示由两个同分异构体组成的拟南芥PGs的结构。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Phosphatidylglycerol (PG) is the major phospholipid of plant chloroplasts. PG from Arabidopsis thaliana has an unusual fatty acyl chain, 3,4-trans-hexdecenoyl (D316:1) in the sn-2 position of the major 18:3/D316:1-PG species, as well as in 18:2/D316:1-PG and 16:0/ D316:1-PG. Upon low-energy collisionally activated dissociation (CAD) in a tandem quadrupole or in an ion-trap mass spectrometer, the [M - H] ions of the PG molecules, containing D316:1-PG give product-ion spectra that are readily distinguishable from those arising from PGs without the D316:1 species. The D316:1-fatty acid-containing PGs are characterized by MS2 product-ion mass spectra that contain predominant [M - H - 236], ions arising from loss of the D316:1-fatty acid substituent as a ketene. This is attributable to the fact that the ¿-hydrogen of the D316:1-fatty acid substituent involved in the ketene loss is an allylic hydrogen, which is very labile. This leads to preferential neutral loss of 236 and provides a sensitive tandem quadrupole mass spectrometric means to identify D316:1-containing PG species in lipid mixtures. The low-energy tandem mass spectrometric approach also permits the structures of the Arabidopsis PGs that consist of two isomeric structures to be unveiled.