Biochemical and physicochemical studies on renin

Abstract

1. 1. Enzymatic and chemical properties of renin of various degrees of purity were investigated. 2. 2. The stability of renin in such preparations was determined under various conditions of temperature, pH, ionic strength, and alcohol and acetone concentrations. With this information available, optimum conditions were selected for the isolation of renin in large-scale preparations, for its purification and storage, and for the separation of undesirable substances. 3. 3. Various aspects of the bio-assay for renin have been investigated, such as the detection of shock-producing substances and the response to increasing amounts of renin or to repeated injections. A survey has also been made to ascertain possible interference by chemicals used routinely for the fractionation of renin or for its stabilization. 4. 4. Some of the biochemical properties of renin such as the “ in vitro” formation of hypertensin and the neutralization by antirenin have been considered briefly. 5. 5. Electrophoretic analysis revealed the presence of two components in a renin preparation obtained after 34,000-fold purification, indicating a purity of about 65 % with respect to renin, in a renin preparation with a specific activity of 470 units/mg. 6. 6. Highly purified renin was found to be very susceptible to inactivation, but stabilization could be accomplished by pyrophosphate, by glycine, or merely by the presence of inert proteins. On this basis, incidental traces of metal were suspected as a possible cause for the inactivation, but this could not be confirmed by the direct addition of metal salts in low concentrations. 7. 7. Metal salts, e.g., 0.001 M gold chloride, were found to abolish all of the biochemical properties of renin, the ability to elevate blood pressure, to induce formation of antirenin in animals, and to cause proteinuria and diuresis in the rat. 8. 8. The solubility of renin as a function of ammonium sulfate and renin concentration has been investigated.