L-amino acid oxidase from Naja atra venom activates and binds to human platelets |
| |
Authors: | Li Rui Zhu Shaowen Wu Jianbo Wang Wanyu Lu Qiumin Clemetson Kenneth J |
| |
Institution: | Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650223, China;Theodor Kocher Institute, University of Berne, Berne CH-3012, Switzerland |
| |
Abstract: | An L -amino acid oxidase (LAAO), NA-LAAO, was purified from the venom of Naja atra. Its N-terminal sequence shows great similarity with LAAOs from other snake venoms. NA-LAAO dose-dependently induced aggregation of washed human platelets. However, it had no activity on platelets in platelet-rich plasma. A low concentration of NA-LAAO greatly promoted the effect of hydrogen peroxide, whereas hydrogen per oxide itself had little activation effect on plate lets. NA-LAAO induced tyrosine phosphorylation of a number of platelet proteins including Src kinase, spleen tyrosine kinase, and phospholipase C γ2. Unlike convulxin, Fc receptor γ chain and T lymphocyte adapter protein are not phosphorylated in NA-LAAO-activated platelets, suggesting an activation mechanism different from the glycoprotein VI pathway. Catalase inhibited the platelet aggregation and platelet protein phosphorylation induced by NA-LAAO. NA-LAAO bound to fixed platelets as well as to platelet lysates of Western blots. Furthermore, affinity chromatography of platelet proteins on an NA-LAAO-Sepharose 4B column isolated a few platelet membrane proteins, suggesting that binding of NA-LAAO to the platelet membrane might play a role in its action on platelets. |
| |
Keywords: | L-amino acid oxidase Naja atra platelet hydrogen peroxide |
本文献已被 维普 PubMed 等数据库收录! |
|