L-amino acid oxidase from Naja atra venom activates and binds to human platelets

Acta Biochimica Et Biophysica Sinica
Rui LiKenneth J Clemetson

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 peroxide itself had little activation effect on platelets. NA-LAAO induced tyrosine phosphorylation of a number of platelet proteins including Src kinase, spleen tyrosine kinase, and phospholipase Cgamma2. Unlike convulxin, Fc receptor gamma 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.

Citations

Jun 19, 2014·The Journal of Venomous Animals and Toxins Including Tropical Diseases·Tássia R CostaSuely V Sampaio
Jun 16, 2009·Toxicon : Official Journal of the International Society on Toxinology·Shu-Rong ZhongQiu-Min Lu
Apr 28, 2009·Toxicon : Official Journal of the International Society on Toxinology·Ji-Fu WeiShao-Heng He
Aug 15, 2015·The Journal of Venomous Animals and Toxins Including Tropical Diseases·Karla C F BordonEliane C Arantes
Feb 1, 2011·Toxicon : Official Journal of the International Society on Toxinology·Tamara SajevicIgor Križaj
Nov 27, 2020·International Journal of Biological Macromolecules·Luana Gonçalves BarbosaRenata Santos Rodrigues
Aug 17, 2021·The Journal of Venomous Animals and Toxins Including Tropical Diseases·Emídio BeraldoDaniel Carvalho Pimenta
May 5, 2011·Biochimica Et Biophysica Acta·Gustavo B NaumannEladio F Sanchez

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