SNX-325, a novel calcium antagonist from the spider Segestria florentina.

A novel selective calcium channel antagonist peptide, SNX-325, has been isolated from the venom of the spider Segestria florentina. The peptide was isolated using as bioassays the displacement of radioiodinated omega-conopeptide SNX-230 (MVIIC) from rat brain synaptosomal membranes, as well as the inhibition of the barium current through cloned expressed calcium channels in oocytes. The primary sequence of SNX-325 is GSCIESGKSCTHSRSMKNGLCCPKSRCNCRQIQHRHDYLGKRKYSCRCS, which is a novel amino acid sequence.

Fluorescence spectroscopy studies of the effects of pyrethroids on the DPPC vesicles.

The interactions of pyrethroids with membrane lipids have been studied by means of fluorescent membrane probe DPH. Pyrethroids located in the interior hydrophobic regions of the lipid bilayer, differed in their effectiveness of lowering the phase transition temperature and in their ability to broaden the temperature range of this transition. With the increase in the concentrations of pyrethroids, the effects of disordering hydrocarbon packing were increased by pyrethroids.