title: A lethal cardiotoxic-cytotoxic protein from the Indian monocellate cobra (Naja kaouthia) venom.
abstract: A lethal cardiotoxic-cytotoxic protein (mol. wt. 6.76 kDa) has been purified from the Indian monocellate cobra (Naja kaouthia) venom by ion-exchange chromatography and HPLC. CD spectra indicated the presence of 23% alpha helix, 19% beta sheets and 35% coil. Complete amino acid sequence was determined by MALDI, which showed similar homology with cardiotoxins/cytotoxins isolated from venom of other Naja species. Intraperitoneal LD(50) was 2.5 mg kg(-1) in BalbC male mice. In vitro cardiotoxicity studies on isolated guinea pig auricle showed that the molecule produced auricular blockade that was abolished after trypsin treatment. Cytotoxicity studies on human leukemic U937 and K562 cells showed that it significantly inhibited cell proliferation in a dose and time dependent manner, as observed by trypan blue exclusion method and tetrazolium bromide reduction assay. IC(5)(0) on U937 and K562 cells were 3.5 microg/ml and 1.1 microg/ml respectively. Morphometry and cell sorting studies indicated apoptosis induction in toxin treated leukemic cells. Apoptosis was caspase 3 and 9 dependent and the treated leukemic cells were arrested in sub-G1 stage. There was an increase in Bax-Bcl2 ratio, decrease in HSP (Heat shock protein) 70 and HSP90 and induction of PARP cleavage after NK-CT1 treatment. The toxin showed low cytotoxic effect on normal human leukocytes as compared with imatinib mesylate. Further detailed cytotoxic and cardiotoxic effects at the molecular level are in progress.
authors.affiliation: Drug Development, Diagnostics and Biotechnology Division, Indian Institute of Chemical Biology, 4 Raja S. C. Mullick Road, Kolkata 700032, India.
authors.forename: Anindita
authors.initials: A
authors.lastname: Debnath
authors.forename: Archita
authors.initials: A
authors.lastname: Saha
authors.forename: Antony
authors.initials: A
authors.lastname: Gomes
authors.forename: Sumit
authors.initials: S
authors.lastname: Biswas
authors.forename: Pinakpani
authors.initials: P
authors.lastname: Chakrabarti
authors.forename: Biplab
authors.initials: B
authors.lastname: Giri
authors.forename: Ajoy K
authors.initials: AK
authors.lastname: Biswas
authors.forename: Shubho Das
authors.initials: SD
authors.lastname: Gupta
authors.forename: Aparna
authors.initials: A
authors.lastname: Gomes
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D054715:Cardiotoxins / Q000737:chemistry / Q000302:isolation & purification / Q000633:toxicity*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D004179:Cobra Cardiotoxin Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000633:toxicity*; D003603:Cytotoxins / Q000737:chemistry / Q000302:isolation & purification / Q000633:toxicity*; D006168:Guinea Pigs; D006801:Humans; D066298:In Vitro Techniques; D007928:Lethal Dose 50; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D014357:Trypsin / Q000737:chemistry
chemical_list: D054715:Cardiotoxins; D004179:Cobra Cardiotoxin Proteins; D003603:Cytotoxins; D014357:Trypsin