Heparin prevents the binding of phospholipase A2 to phospholipid micelles: importance of the amino-terminus.
Heparin prevents the binding of phospholipase A2 to phospholipid micelles: importance of the amino-terminus.
复制标题
肝素可阻止磷脂酶 A2 与磷脂胶束的结合：氨基末端的重要性。
DOI：
10.1021/bi00101a026
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发表时间：
1991
期刊：
影响因子：
2.9
通讯作者：
Harmony,JA
中科院分区：
文献类型：
--
作者：
Diccianni,MB;Lilly-Stauderman,M;McLean,LR;Balasubramaniam,A;Harmony,JA
1991年7月3日收到的修订版Mandarin pt摘要：猪胰磷脂酶A2（PLA 2）的主要亚型（命名为B-PLA 2）对胶束底物的活性受到肝素的抑制。抑制是酶与肝素结合的结果，由肝素诱导的B-PLA 2的固有荧光和8-苯胺基-1-萘磺酸盐荧光的改变以及活性位点残基His-48的化学修饰的增强速率记录。作为肝素结合的结果，B-PLA 2在活性位点和氨基末端的构象被改变，并且酶不结合磷脂胶束。尽管肝素诱导的构象变化，B-PLA 2保留其催化单体磷脂水解的能力。其他糖胺聚糖可以结合并抑制B-PLA 2对有机磷脂的活性，但没有一种测试像肝素一样有效。胰腺酶的同种型，命名为UB-PLA 2，对应于同种猪PLA 2，不与肝素结合，其催化活性也不受肝素影响。对应于B-PLA 2的氨基末端26个残基的肽可以从肝素抑制中拯救PLA 2。对应于UB-PLA 2的氨基末端的类似肽对肝素抑制没有影响。本文提出了肝素抑制B-PLA_2的模型，肝素的催化作用是直接与B-PLA_2的氨基端（界面识别位点）相互作用，阻止酶与胶束底物结合。核磷脂酶A2（PLA 2;* EC 3.1. 1.4)包括一类钙离子依赖性脂解酶，其在有机脂-水界面催化脂水解。PLA 2催化二酰基磷脂中sn-2脂肪酰基酯键的水解，释放游离脂肪酸和单酰基磷脂（de哈斯&货车Deenen，1964; Waite，1987）。
Revised Manuscript Received July 3, 1991 abstract: The activity of the major isoform of porcine pancreatic phospholipase A2 (PLA2), designated B-PLA2, against micellar substrates is inhibited by heparin. Inhibition is a consequence of binding of the enzyme to heparin, documented by a heparin-induced alteration in the intrinsic fluorescence of B-PLA2 and in the 8-anilino-1-naphthalene sulfonate fluorescence and by the enhanced rate of chemical modification of the active site residue His-48. As a consequence of heparin binding, the conformation of B-PLA2 at the active site and at the amino-terminus is altered, and the enzyme does not bind to phospholipid micelles. In spite of the heparin-induced conformational changes, B-PLA2 retains its ability to catalyze the hydrolysis of monomeric phospholipid. Other glycosaminoglycans can bind to and inhibit the activity of B-PLA2 toward organized phospholipids, but none tested is as effective as heparin. An isoform of the pancreatic enzyme, designated UB-PLA2 and which corresponds to iso-pig PLA2, does not bind to nor is its catalytic activity influenced by heparin. A peptide corresponding to the amino-terminal 26 residues of B-PLA2 can rescue PLA2 from heparin inhibition. A similar peptide corresponding to the amino-terminus of UB-PLA2 has no effect on heparin inhibition. A model for the inhibition of B-PLA2 by heparin is proposedin which the catalytically significant effect of heparin is to interact directlywith the amino-terminus of B-PLA2, the interfacial recognition site, to prevent the enzyme from binding to micellar substrates.^ Riospholipases A2 (PLA2;* EC 3.1. 1.4) comprise a class of calcium ion dependent lipolytic enzymes that catalyze lipid hydrolysis at an organized lipid-water interface. PLA2 cat-alyzes the hydrolysis of the sn-2 fatty acyl ester linkage in diacylphospholipids, liberating free fatty acids and mono-acylphospholipids (de Haas & van Deenen, 1964; Waite, 1987).