Interaction of Ca 2+ with endoplasmic reticulum of rat liver: a standardized procedure for the isolation of rat liver microsomes

A standardized method has been developed for the rapid isolation of rat liver microsomes using Ca²⁺ and its advantages over other available methods have been outlined. In addition to hydrolytic enzymes and chemical composition, the important enzymes in the electron transport system were determined in Ca²⁺ microsomes and normal 105,000g microsomes and indicate only minor differences between the two preparations. Two classes of microsomes—smooth and rough particles prepared with or without the addition of Ca²⁺—were compared for their chemical and biochemical properties and indicated little differences within each microsomal fraction. The ability of other divalent cations like Mg²⁺, Fe²⁺, Ba²⁺, Zn²⁺, and Hg²⁺ to aggregate the microsomes was observed while the monovalent and trivalent cations tested did not appreciably sediment the microsomes under the present experimental conditions.