Title:
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Isolation, structural characterisation and mode
of action of bioactive agents from arachnid and reptile venoms
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Selected snake and spider venom fractions were screened for in-vitro insulinotropic
activity in glucose responsive BRIN-BDll cells, with insulin secretion measured using
radioimmunoassay. Significant insulin secretion was noted for 27 snake venom
fractions, containing a diverse range of snake toxin families including phospholipases
A2, a-neurotoxins, disintegrins, serine proteinases, CRISP (cysteine-rich secretory
proteins), metalloproteinases and nucleotidases. The partial N-terminal sequences are
reported for 15 snake venom components. Elevated levels of insulin secretion were
recorded for 16 fractions from the Grammostola rosea venom and 31 fractions from the
Aphonopelma chalcodes venom. The synthetic version of a novel 28 amino acid
residue peptide isolated from the Aphonopelma chalcodes produced a significant
concentration dependent increase in insulin secretion. A number of theraphotoxins are
proposed as constituents of the active Aphonopelma chalcodes fractions. Paliial
sequences are presented for 3 unknown Grammostola rosea peptides with insulinotropic
activity reported as a novel function of a number of known Grammostola peptides.
A microtitre assay was used to assess antimicrobial activity of snake and spider
venom against both Gram-positive and Gram-negative bacteria. Snake venom fi.-actions
containing an L-amino acid oxidase or metalloproteinase component showed
preferential activity against Staphylococcus aureus, while phospholipases A2 were most
active against Bacillus subtilis. Activity against Salmonella typhimurium was greatest
for fractions containing L- amino acid oxidase. Escherichia coli was least susceptible
to the test fractions. Antimicrobial activity for the Aphonopelma chalcodes crude
venom was confmed to fractions 26 to 35, containing low mass compounds of mJz 730-
830 alongside a peptide component of mJz 2919, for which the novel sequence is
reported.
A quantitative study was performed on the selected low molecular mass
components isolated ill the Hap/ope/rna lividurn spider venom usmg liquid
chromatography / electro spray ionisation mass spectrometry. This study of the
bioactive constituents of snake and spider venom serves to enhance the existing body of
evidence supporting the study of venomics in pursuit of novel leads for pharmaceutical
research and development.
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