The distribution among ophidian venoms of a toxin isolated from the venom of the Mojave rattlesnake (Crotalus scutulatus scutulatus).

A toxin analogous to Mojave toxin or protein K' was isolated from venom of the Mojave rattlesnake (Crotalus s. scutulatus) by anion exchange and gel permeation chromatography. This toxin has an apparent native molecular weight of 20,000-22,000, a subunit molecular weight of 14,000 and a pI of 4.9-5.0. The i.p. LD50 is 0.094 mg/kg for mice. A wide variety of ophidian venoms (crotaline, viperine, elapid, hydrophid and colubrid) were examined for the presence of this toxin using Ouchterlony, immunoelectrophoresis, ELISA and Western transfer. High concentrations were found in 4 of 6 C. scutulatus venom samples, 2 of 3 C. durissus samples and samples from C. viridis concolor and C. tigris. A moderate concentration was found in 1 of 3 C. durissus samples and low to trace concentrations in 1 C. durissus sample, 1 C. scutulatus sample, 2 of 12 C. atrox samples and a Trimeresurus flavoviridis sample, the latter being the only instance of detection of the toxin in a snake other than a rattlesnake. The toxin appears in at least two phylogenetic lines of rattlesnakes, and its geographic distribution in North American rattlesnake species resembles a mosaic.