[Age changes in the allosteric properties of brain acetylcholinesterase]

d-tubocurarine and procaine have been shown to inhibit the acetylcholinesterase of rat brain homogenate by coupled and non-competitive mechanism respectively, which suggests binding to enzyme peripheral sites. Judging by values of Hill coefficient negative cooperativity in interactions between procaine sites is characteristic of all ages (n=0,8 and 0,53 for young and old rats) while such cooperativity for d-tubocurarine sites appears only at old age (n=1 and 0,6 for young and old animals). Values of Ki changed in opposite directions for each of the substances with aging. Modification of the enzyme membrane microenvironment with aging was suggested as a reason for differences in enzyme allosteric behaviour.