Jurkowitz M S, Horrocks L A, Litsky M L
Department of Medical Biochemistry, College of Medicine, Room 471, Hamilton Hall, 1645 Neil Avenue, The Ohio State University, Columbus, OH 43210, USA.
Biochim Biophys Acta. 1999 Feb 25;1437(2):142-56. doi: 10.1016/s1388-1981(99)00013-x.
A lysoplasmalogenase (EC 3.3.2.2; EC 3.3.2.5) that liberates free aldehyde from 1-alk-1'-enyl-sn-glycero-3-phospho-ethanolamine or -choline (lysoplasmalogen) was identified and characterized in rat gastrointestinal tract epithelial cells. Glycerophosphoethanolamine was produced in the reaction in equimolar amounts with the free aldehyde. The microsomal membrane associated enzyme was present throughout the length of the small intestines, with the highest activity in the jejunum and proximal ileum. The rate of alkenyl ether bond hydrolysis was dependent on the concentrations of microsomal protein and substrate, and was linear with respect to time. The enzyme hydrolyzed both ethanolamine- and choline-lysoplasmalogens with similar affinities; the Km values were 40 and 66 microM, respectively. The enzyme had no activity with 1-alk-1'-enyl-2-acyl-sn-glycero-3-phospho-ethanolamine or -choline (intact plasmalogen), thus indicating enzyme specificity for a free hydroxyl group at the sn-2 position. The specific activities were 70 nmol/min/mg protein and 57 nmol/min/mg protein, respectively, for ethanolamine- and choline-lysoplasmalogen. The pH optimum was between 6.8 and 7.4. The enzyme required no known cofactors and was not affected by low mM levels of Ca2+, Mg2+, EDTA, or EGTA. The detergents, Triton X-100, deoxycholate, and octyl glucoside inhibited the enzyme. The chemical and physical properties of the lysoplasmalogenase were very similar to those of the enzyme in liver and brain microsomes. In developmental studies the specific activities of the small intestinal and liver enzymes increased markedly, 11.1- and 3.4-fold, respectively, in the first approximately 40 days of postnatal life. A plasmalogen-active phospholipase A2 activity was identified in the cytosol of the small intestines (3.3 nmol/min/mg protein) and liver (0.3 nmol/min/mg protein) using a novel coupled enzyme assay with microsomal lysoplasmalogenase as the coupling enzyme.
在大鼠胃肠道上皮细胞中鉴定并表征了一种溶血缩醛磷脂酶（EC 3.3.2.2；EC 3.3.2.5），该酶可从1-烯基-1'-烯基-sn-甘油-3-磷酸乙醇胺或 - 胆碱（溶血缩醛磷脂）中释放出游离醛。甘油磷酸乙醇胺在反应中与游离醛以等摩尔量产生。与微粒体膜相关的酶存在于小肠全长，在空肠和回肠近端活性最高。烯基醚键的水解速率取决于微粒体蛋白和底物的浓度，并且随时间呈线性关系。该酶以相似的亲和力水解乙醇胺 - 和胆碱 - 溶血缩醛磷脂；Km值分别为40和66 microM。该酶对1-烯基-1'-烯基-2-酰基-sn-甘油-3-磷酸乙醇胺或 - 胆碱（完整缩醛磷脂）无活性，因此表明该酶对sn-2位的游离羟基具有特异性。乙醇胺 - 和胆碱 - 溶血缩醛磷脂的比活性分别为70 nmol/分钟/毫克蛋白和57 nmol/分钟/毫克蛋白。最适pH在6.8至7.4之间。该酶不需要已知的辅因子，并且不受低毫摩尔水平的Ca2+、Mg2+、EDTA或EGTA的影响。去污剂Triton X-100、脱氧胆酸盐和辛基葡糖苷可抑制该酶。溶血缩醛磷脂酶的化学和物理性质与肝脏和脑微粒体中的酶非常相似。在发育研究中，小肠和肝脏酶的比活性在出生后大约40天内分别显著增加，分别增加了11.1倍和3.4倍。使用以微粒体溶血缩醛磷脂酶作为偶联酶的新型偶联酶测定法，在小肠（3.3 nmol/分钟/毫克蛋白）和肝脏（0.3 nmol/分钟/毫克蛋白）的胞质溶胶中鉴定出一种具有缩醛磷脂活性的磷脂酶A2活性。
