Kinetic and mechanistic characterization of the Sphingomyelinases D from Loxosceles intermedia spider venom
Contribuinte(s) |
Universidade Estadual Paulista (UNESP) |
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Data(s) |
20/05/2014
20/05/2014
15/03/2006
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Resumo |
Envenomation by arachnids of the genus Loxosceles leads to local dermonecrosis and serious systemic toxicity mainly induced by sphingomyelinases D (SMase D). These enzymes catalyze the hydrolysis of sphingomyelin resulting in the formation of ceramide-phosphate and choline as well as the cleavage of lysophosphatidyl choline generating the lipid mediator lysophosphatidic acid. We have, previously, cloned and expressed two functional SMase D isoforms, named P1 and P2, from Loxosceles intertnedia venom and comparative protein sequence analysis revealed that they are highly homologous to SMase I from Loxosceles laeta which folds to form an (alpha/beta)(8) barrel. In order to further characterize these proteins, pH dependence kinetic experiments and chemical modification of the two active SMases D isoforms were performed. We show here that the amino acids involved in catalysis and in the metal ion binding sites are strictly conserved in the SMase D isoforms from L. intermedia. However, the kinetic studies indicate that SMase P1 hydrolyzes sphingomyelin less efficiently than P2, which can be attributed to a substitution at position 203 (Pro-Leu) and local amino acid substitutions in the hydrophobic channel that could probably play a role in the substrate recognition and binding. (c) 2005 Elsevier Ltd. All rights reserved. |
Formato |
380-386 |
Identificador |
http://dx.doi.org/10.1016/j.toxicon.2005.12.005 Toxicon. Oxford: Pergamon-Elsevier B.V., v. 47, n. 4, p. 380-386, 2006. 0041-0101 http://hdl.handle.net/11449/34008 10.1016/j.toxicon.2005.12.005 WOS:000236534700002 |
Idioma(s) |
eng |
Publicador |
Elsevier B.V. |
Relação |
Toxicon |
Direitos |
closedAccess |
Palavras-Chave | #Loxosceles venoms #Sphingomyelinase D #sphingomyelin #kinetic parameters #Structure |
Tipo |
info:eu-repo/semantics/article |