title: Fibrinogenolytic toxin from Indian monocled cobra (Naja kaouthia) venom.
abstract: A fibrinogenolytic toxin of molecular weight 6.5 kDa has been purified from the venom of Indian monocled cobra (Naja kaouthia) by repeated cation exchange chromatography on CM-sephadex C-50. The purified toxin did not show any phospholipase activity but was mildly hemolytic on human erythrocytes. This toxin, called Lahirin, cleaved fibrinogen in a dose- and time-dependent manner. The digestion process apparently started with the A alpha chain, and gradually other lower-molecular-weight chains were also cleaved to low-molecular-weight peptides. The fibrinolytic activity was completely lost after treatment with ethylene di-amine tetra acetic acid (EDTA). However, exposure to 100 degree C for 1 min or pre-treatment with phenyl methyl sulfonyl fluoride (PMSF) did not affect the fibrinolytic activity. Cleavage of di-sulphide bonds by beta-mercaptoethanol or unfolding the protein with 4 M urea caused complete loss of activity of pure Lahirin.
authors.affiliation: Department of Biological Sciences, Birla Institute of Technology and Science-Pilani, KK Birla Goa Campus, Zuarinagar, Goa 403726, India.
authors.forename: C Chandra
authors.initials: CC
authors.lastname: Sekhar
authors.forename: Dibakar
authors.initials: D
authors.lastname: Chakrabarty
mesh_terms: D000818:Animals; D004546:Elapid Venoms / Q000494:pharmacology*; D017815:Elapidae; D057075:Enzyme Assays; D004795:Enzyme Stability; D004912:Erythrocytes / Q000187:drug effects; D005340:Fibrinogen / Q000737:chemistry; D005343:Fibrinolytic Agents / Q000302:isolation & purification / Q000494:pharmacology*; D053878:Hemolytic Agents / Q000494:pharmacology*; D006801:Humans; D008970:Molecular Weight; D010455:Peptides / Q000302:isolation & purification / Q000494:pharmacology*
chemical_list: D004546:Elapid Venoms; D005343:Fibrinolytic Agents; D053878:Hemolytic Agents; D010455:Peptides; C561570:lahirin protein, Naja kaouthia; D005340:Fibrinogen