Arthur G, Choy P C
Biochim Biophys Acta. 1984 Sep 12;795(2):221-9. doi: 10.1016/0005-2760(84)90069-9.
The acyl specificity of 1,2-diacylglycerol: CDP-choline phosphocholine transferase (EC 2.7.8.2) for the formation of phosphatidylcholine with the appropriate acyl groups in hamster heart was investigated. Enzyme activity was determined in the microsomal fraction with 1,2-diacylglycerols of known acyl content. Maximum enzyme activity was obtained with diacylglycerol containing a monoenoic acyl group at the C-2 position of the glycerol moiety, regardless of the acyl group at the C-1 position. The specificity of the enzymes was also investigated by perfusing the isolated hamster heart with labelled glycerol. Comparison of the molecular species of the labelled diacylglycerols and phosphatidylcholine subsequent to perfusion revealed that the specificity of phosphocholine transferase was not limited to the monoenoic species of diacylglycerol. The difference in specificity observed between the in vitro assay and the perfusion study may partly be attributed to the presence of detergent in the enzyme assay mixture (to facilitate solubility of diacylglycerol). It is concluded that in the hamster heart, phosphocholine transferase has only limited ability to select the appropriate acyl groups for phosphatidylcholine biosynthesis. It appears that the majority of the newly formed phosphatidylcholine in the heart via the CDP-choline pathway is subsequently resynthesized by deacylation-reacylation process.
研究了仓鼠心脏中1,2 - 二酰基甘油：CDP - 胆碱磷酸胆碱转移酶（EC 2.7.8.2）在形成具有适当酰基的磷脂酰胆碱时的酰基特异性。用已知酰基含量的1,2 - 二酰基甘油在微粒体部分测定酶活性。无论甘油部分C - 1位的酰基如何，在甘油部分C - 2位含有单烯酰基的二酰基甘油可获得最大酶活性。还通过用标记的甘油灌注分离的仓鼠心脏来研究酶的特异性。灌注后对标记的二酰基甘油和磷脂酰胆碱的分子种类进行比较，结果表明磷酸胆碱转移酶的特异性不限于二酰基甘油的单烯种类。体外测定和灌注研究之间观察到的特异性差异可能部分归因于酶测定混合物中存在去污剂（以促进二酰基甘油的溶解性）。得出的结论是，在仓鼠心脏中，磷酸胆碱转移酶在为磷脂酰胆碱生物合成选择适当酰基方面的能力有限。看来，心脏中通过CDP - 胆碱途径新形成的大部分磷脂酰胆碱随后通过脱酰基 - 再酰基化过程重新合成。
