A quantitative assessment of variation in venom constituents within and between three nominal rattlesnake subspecies.

Gel filtration profiles of crude snake venoms from 38 Crotalus viridis, representing the nominal subspecies concolor, viridis and lutosus, were compared. Mean protein concentration is greatest in C. v. concolor. Individual fractions show up to 9-fold variation in protein content within taxa, and 23-fold with all specimens considered together. Small myotoxins are the major components in C. v. concolor and C. v. viridis venoms, comprising an average of 37% and 44% of total venom protein, respectively. In C. v. lutosus, fractions 1 and 2 each account for 26% of total protein. The three taxa are readily distinguished on the basis of quantitative and qualitative differences in gel filtration elution profiles.