title: Structural and functional analyses of DM43, a snake venom metalloproteinase inhibitor from Didelphis marsupialis serum.
abstract: DM43, an opossum serum protein inhibitor of snake venom metalloproteinases, has been completely sequenced, and its disulfide bond pattern has been experimentally determined. It shows homology to human alpha(1)B-glycoprotein, a plasma protein of unknown function and a member of the immunoglobulin supergene family. Size exclusion and dynamic laser light scattering data indicated that two monomers of DM43, each composed of three immunoglobulin-like domains, associated to form a homodimer in solution. Analysis of its glycan moiety showed the presence of N-acetylglucosamine, mannose, galactose, and sialic acid, most probably forming four biantennary N-linked chains. DM43 inhibited the fibrinogenolytic activities of bothrolysin and jararhagin and formed 1:1 stoichiometric stable complexes with both metalloproteinases. DM43 was ineffective against atrolysin C or A. No complex formation was detected between DM43 and jararhagin C, indicating the essential role of the metalloproteinase domain for interaction. Homology modeling based on the crystal structure of a killer cell inhibitory receptor suggested the existence of an I-type Ig fold, a hydrophobic dimerization surface and six surface loops potentially forming the metalloproteinase-binding surface on DM43.
authors.affiliation: Departamento de Fisiologia e Farmacodinâmica, Instituto Oswaldo Cruz, Fiocruz, 21045-900 Rio de Janeiro, Brazil.
authors.forename: Ana G C
authors.initials: AG
authors.lastname: Neves-Ferreira
authors.forename: Jonas
authors.initials: J
authors.lastname: Perales
authors.forename: Jay W
authors.initials: JW
authors.lastname: Fox
authors.forename: John D
authors.initials: JD
authors.lastname: Shannon
authors.forename: Débora L
authors.initials: DL
authors.lastname: Makino
authors.forename: Richard C
authors.initials: RC
authors.lastname: Garratt
authors.forename: Gilberto B
authors.initials: GB
authors.lastname: Domont
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001798:Blood Proteins / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D017837:Bothrops; D003435:Crotalid Venoms / Q000201:enzymology*; D008666:Metalloendopeptidases / Q000037:antagonists & inhibitors*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009893:Opossums; D011480:Protease Inhibitors / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D020836:Protein Structure, Quaternary; D017386:Sequence Homology, Amino Acid
chemical_list: D001798:Blood Proteins; D003435:Crotalid Venoms; C454462:DM43 protein, Didelphis marsupialis; D011480:Protease Inhibitors; D008666:Metalloendopeptidases