CONVERSION OF LOW MOLECULAR WEIGHT RENIN INTO THE HIGH MOLECULAR WEIGHT FORM BY Cu²⁺ IN THE RAT KIDNEY

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The low molecular weight form of renin (M.W. 40000) in the extract of rat kidneycortex was converted into the high molecular weight form (M.W. 60000) in the presence of Cu²⁺ and this conversion was abolished following pretreatment of the extract with disodium ethylenediaminetetraacetic acid. Fe³⁺, Fe(CN)₆^3-, Cd²⁺ and Zn²⁺ had no effects on the reaction of the molecular weight conversion of this enzyme. The reactivity in the formation of high molecular weight renin catalyzed by Cu²⁺ increased when the extract was previously dialyzed, indicating the presence of substance (s) that interfere with the binding reaction of renin. The high molecular weight renin produced Cu²⁺ was stable against dithiothreitol, suggesting that the formation of disulphide bridge (s) is not involved in the reaction of renin with the renin binding substance. We also confirmed that for formation of the high molecular weight renin, Cu²⁺ must react with both the renin enzyme and the renin binding substance. Our findings provide new evidence related to the mechanism of molecular weight conversion of renin in the rat kidney.