title: Molecular cloning and characterization of a neurotoxic phospholipase A2 from the venom of Taiwan habu (Trimeresurus mucrosquamatus).
abstract: Using gel-filtration chromatography and reverse-phase (RP) HPLC we have purified a presynaptic neurotoxin (designated as trimucrotoxin) from the crude venom of Taiwan habu (Trimeresurus mucrosquamatus). Its complete primary structure was solved by an automated N-terminal sequencing and cDNA sequencing method. The enzyme inhibited the twitch of the chick biventer cervicis muscle at 0.1-1 micrograms/ml and showed lethality in mice (LD50 = 1.2 micrograms/g, when given intravenously). Trimucrotoxin exists mainly as a homodimer of 14 kDa subunits as shown by a gel-filtration experiment, and dissociates into monomers during SDS/PAGE in the absence of Ca2+. However, most of trimucrotoxin migrated as slowly as a trimer during nondenaturing SDS/PAGE in the presence of Ca2+ or Sr2+. Its amino acid sequence identity to crotoxin B and agkistrodotoxin is about 75%, and its cDNA sequence is 82% identical to that of crotoxin B. Rabbit antiserum against trimucrotoxin also cross-reacted with the other crotalid neurotoxic phospholipases A2. Furthermore, the purified acidic subunit of crotoxin potentiated the neurotoxicity of trimucrotoxin. A comparison of the sequences of these crotalid neurotoxins revealed some common features of the possible neurotoxic sites, including residues 6, 11, 76-81 and 119-125.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002645:Chickens; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D003001:Cloning, Molecular; D003435:Crotalid Venoms / Q000201:enzymology*; D003439:Crotoxin / Q000737:chemistry* / Q000235:genetics / Q000494:pharmacology*; D018076:DNA, Complementary / Q000032:analysis / Q000235:genetics; D054501:Group II Phospholipases A2; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D051379:Mice; D008813:Mice, Inbred ICR; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009498:Neurotoxins / Q000737:chemistry* / Q000235:genetics / Q000494:pharmacology*; D010741:Phospholipases A / Q000737:chemistry* / Q000235:genetics / Q000494:pharmacology*; D054467:Phospholipases A2; D011817:Rabbits; D051381:Rats; D017208:Rats, Wistar; D017386:Sequence Homology, Amino Acid; D017841:Trimeresurus
chemical_list: D003435:Crotalid Venoms; D018076:DNA, Complementary; D009498:Neurotoxins; C029748:Trimeresurus venoms; D003439:Crotoxin; D010741:Phospholipases A; D054501:Group II Phospholipases A2; D054467:Phospholipases A2; C096805:trimucrotoxin