title: Heteromtoxin (HmTx), a novel heterodimeric phospholipase A(2) from Heterometrus laoticus scorpion venom.
abstract: Heteromtoxin (HmTx) is a group III phospholipase A(2) produced in Heterometrus laoticus, in Thailand. In this study, HmTx was purified from venom by separation chromatography, and the PLA(2) activity of the fractions was determined by lecithin agar assay. The enzyme is an acidic protein with a pI of 5.6 and an apparent molecular weight of 14018.4 Da. The nucleotide sequence of HmTx contains 649 bp, and the mature protein is predicted to have 131 amino acid residues-104 of which make up the large subunit, and 27 of which make up the small subunit. The subunit structure of HmTx is highly similar to that of the other toxin, Pandinus imperator imperatoxin I (IpTx(i)) and to Mesobuthus tamulus phospholipase A(2) (MtPLA(2)). The 3D-structure of HmTx consists of three conserved alpha-helices: h1 (Lys24-His34), h2 (Cys59-Asp71), and h3 (Ala80-Phe89). The beta-sheet consisted of a single stranded anti-parallel beta-sheet (b1.1 at Glu43-Lys45 and b1.2 at Lys48-Asn50) that was highly similar to the conserved sequences (-CGXG-, -CCXXHDXC- and CXCEXXXXXC-) of Apis mellifera (bee) phospholipases.
authors.affiliation: Protein and Proteomics Research Group (PPRG), Department of Biochemistry, Faculty of Science, Khon Kaen University, Khon Kaen 40002, Thailand.
authors.forename: Paroonkorn
authors.initials: P
authors.lastname: Incamnoi
authors.forename: Rina
authors.initials: R
authors.lastname: Patramanon
authors.forename: Sompong
authors.initials: S
authors.lastname: Thammasirirak
authors.forename: Arunrat
authors.initials: A
authors.lastname: Chaveerach
authors.forename: Nunthawun
authors.initials: N
authors.lastname: Uawonggul
authors.forename: Sophida
authors.initials: S
authors.lastname: Sukprasert
authors.forename: Prapenpuksiri
authors.initials: P
authors.lastname: Rungsa
authors.forename: Jureerut
authors.initials: J
authors.lastname: Daduang
authors.forename: Sakda
authors.initials: S
authors.lastname: Daduang
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D018076:DNA, Complementary / Q000235:genetics; D004591:Electrophoresis, Polyacrylamide Gel; D008957:Models, Genetic; D008958:Models, Molecular; D008969:Molecular Sequence Data; D008970:Molecular Weight; D054467:Phospholipases A2 / Q000737:chemistry* / Q000235:genetics; D010802:Phylogeny; D012604:Scorpion Venoms / Q000201:enzymology* / Q000235:genetics; D012605:Scorpions / Q000737:chemistry* / Q000235:genetics; D017386:Sequence Homology, Amino Acid
chemical_list: D018076:DNA, Complementary; D012604:Scorpion Venoms; D054467:Phospholipases A2; C581456:heteromtoxin, Heterometrus laoticus