title: Conformational changes of Loxosceles venom sphingomyelinases monitored by circular dichroism.
abstract: Envenomation by arachnids of the genus Loxosceles can induce a variety of biological effects, including dermonecrosis and hemolysis. We have previously identified in L. intermedia venom two highly homologous proteins with sphingomyelinase activity, termed P1 and P2, responsible for all these pathological events, and also an inactive isoform P3. The toxins P1 and P2 displayed 85% identity with each other at the amino acid level and showed a 57% identity with SMase I, an active toxin from L. laeta venom. Circular dichroism was used to determine and compare the solution structure of the active and inactive isoforms. Effects of pH and temperature change on the CD spectra of the toxins were investigated and correlated with the biological activities. This study sheds new light on the structure-function relationship of homologous proteins with distinct biological properties and represents the first report on the structure-function relationship of Loxosceles sphingomyelinases D.
authors.affiliation: Laboratório de Imunoquímica, Instituto Butantan, SP, Brazil.
authors.forename: Sonia A
authors.initials: SA
authors.lastname: de Andrade
authors.forename: Matheus F Fernandes
authors.initials: MF
authors.lastname: Pedrosa
authors.forename: Rute M Gonçalves
authors.initials: RM
authors.lastname: de Andrade
authors.forename: Maria Luiza Vilela
authors.initials: ML
authors.lastname: Oliva
authors.forename: Carmen W
authors.initials: CW
authors.lastname: van den Berg
authors.forename: Denise V
authors.initials: DV
authors.lastname: Tambourgi
mesh_terms: D000818:Animals; D001665:Binding Sites; D002942:Circular Dichroism; D006461:Hemolysis; D006863:Hydrogen-Ion Concentration; D010727:Phosphoric Diester Hydrolases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D020033:Protein Isoforms / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017433:Protein Structure, Secondary; D013108:Sphingomyelin Phosphodiesterase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D013111:Spider Venoms / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D013112:Spiders / Q000201:enzymology / Q000235:genetics; D013696:Temperature
chemical_list: D020033:Protein Isoforms; D013111:Spider Venoms; C055161:loxosceles venom; D010727:Phosphoric Diester Hydrolases; D013108:Sphingomyelin Phosphodiesterase