کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
2066250 1076982 2006 7 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Kinetic and mechanistic characterization of the Sphingomyelinases D from Loxosceles intermedia spider venom
موضوعات مرتبط
علوم زیستی و بیوفناوری بیوشیمی، ژنتیک و زیست شناسی مولکولی بیوشیمی، ژنتیک و زیست شناسی مولکولی (عمومی)
پیش نمایش صفحه اول مقاله
Kinetic and mechanistic characterization of the Sphingomyelinases D from Loxosceles intermedia spider venom
چکیده انگلیسی

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 intermedia venom and comparative protein sequence analysis revealed that they are highly homologous to SMase I from Loxosceles laeta which folds to form an (α/β)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.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Toxicon - Volume 47, Issue 4, 15 March 2006, Pages 380–386
نویسندگان
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