Phylogenetic relationships of snake venom toxic proteins.

Two kinds of distance matrices have been formed from minimum mutational distances and absolute hydrophobicity differences obtained by comparison of aligned homologous sequences of 56 toxins from venom of snakes belonging to 7 genera. Phylogenetic trees were constructed from these distance matrices, employing the unweighted pair-group method using arithmetic averages (UPGMA). The Pearson product-moment correlation coefficient has been used to estimate the agreement between the original distance matrix and that obtained directly from the dendrogram. For all these procedures the set of computer programs PHYTREE (written in BASIC for micro-computer, and available from the author) has been used.