Preparation of active, drug-metabolizing, microsomal enzymes under optimal conditions and by iso-electric precipitation

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Abstract
The influences of homogenization technique and of relative centrifugal force on the enzyme activity of hepatic microsomes have been investigated to establish optimal conditions for preparation. In general, a glass or Ultra Turrax homogenizer provided a satisfactory homogenate having maximal enzyme activity when nuclear and mitochondrial material were removed by centrifugation at >6500 g for 20 min. Esterase, UDP-transglucuronylase, reductase and oxidase activities of microsomes prepared from liver breis under optimal conditions from guinea-pig, rabbit and rat have been compared. The enzyme activities in microsomes prepared by isoelectric precipitation at pH 5·0 were similar to those prepared by differential centrifugation except for a 50–75% reduction in glucuronyl transferase activity observed in rabbit and guinea-pig.