Inhibition of acetylcholinesterase of mice erythrocytes & synaptosomes by dimethylsulfoxide.

ABSTRACT

In vitro inhibitory effect of dimethylsulfoxide (DMSO) on acetylcholinesterase of erythrocyte membranes and synaptosomes of mice was observed using acetylthiocholine as substrate. DMSO inhibited the enzyme from both sources and the effect was concentration dependent. It produced an inhibition of 26 to 28 per cent at a concentration of 0.13 mM and 92 to 95 per cent at a higher concentration of 1.91 mM. The Km of bound and solubilized enzyme of the synaptosomes was 0.2 and 0.15 mM while that of erythrocyte membranes 0.5 and 0.33 mM respectively. The Vmax was 0.4 and 0.4 (for synaptosomes) and 0.67 and 0.59 (for erythrocyte membranes) Mmoles/mg protein/min, respectively for bound and solubilized forms. The Ki of solubilized enzyme of synaptosomes was 0.11 mM. Kinetic studies showed that the inhibition was competitive in nature.