Purification, amino-acid sequence and partial characterization of two toxins with anti-insect activity from the venom of the South American scorpion Tityus bahiensis (Buthidae).
We report here the isolation by a two-step chromatographic procedure of two new toxins from the South American scorpion Tityus bahiensis. Their amino-acid sequences and some of their biological features were established. The two toxins have different biological properties. Toxin TbIT-I had almost no activity or pharmacological effects in vertebrate tissues whereas it was lethal to house flies (LD50 80.0 ng/house fly). In contrast, Tb2-II was active against both mammals (intracerebroventricular injection of 100 ng/mouse was lethal) and insects (LD50 40.0 ng/house fly). The amino-acid sequences of these toxins were established and found to be similar (60-95%) to previously described beta-toxins from the Tityus genus. Based on the available comparative information, this study attempts identify possible structure-function relationships that may be responsible for the differences in bioactivity displayed by these toxins.
Departamento de Fisiologia e Biofísica, ICB, Universidade Federal de Minas Gerais, 31270-901, MG, Belo Horizonte, Brazil. piment@jean-roche.univ-mrs.fr
A M
AM
Pimenta
M
M
Martin-Eauclaire
H
H
Rochat
S G
SG
Figueiredo
E
E
Kalapothakis
L C
LC
Afonso
M E
ME
De Lima
D000595:Amino Acid Sequence; D000818:Animals; D002850:Chromatography, Gel; D004591:Electrophoresis, Polyacrylamide Gel; D004797:Enzyme-Linked Immunosorbent Assay; D006135:Gryllidae; D006793:Houseflies; D007313:Insecta / Q000502:physiology*; D015640:Ion Channel Gating / Q000187:drug effects; D008958:Models, Molecular; D010526:Periplaneta; D012604:Scorpion Venoms / Q000737:chemistry*; D012605:Scorpions / Q000502:physiology*; D015222:Sodium Channels / Q000187:drug effects; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D014118:Toxins, Biological / Q000737:chemistry* / Q000633:toxicity*
D012604:Scorpion Venoms; D015222:Sodium Channels; D014118:Toxins, Biological