EN
Proteinase inhibitors from squash seeds were analyzed for mutational variability. The non-homologous positions were subjected to an analysis of the interrelation between occurring residues and the mechanism of variability, using the algorithm of genetic semihomology [1]. The study also concerned mutational correlation at particular positions and their contact with each other. It was observed that: the number of residues occupying particular positions varies from 1 to 8 the mechanism of variability is based on single point mutation the variable positions are seldom in contact with each other the mutations in distant positions (not in contact with each other) are correlated with each other the correlated mutations refer to those positions which are far from the reactive site of the inhibitor the mutational variability in primary structure within this family is not consistent with the Markovian model of amino acid replacement.