Relationship between molecular weight conversion and renin activity in dog renal renin

A normal size form of renin, which seems to be a storage form in renin granules, changed neither in molecular weight nor activity by acidification to pH 3.0. High molecular weight (HMW) renin fractionated by gel chromatography from crude renal extract prepared with thiol group blockers was converted into normal size renin by acdification, accompanied with an increase in renin activity by about 50%. The molecular weight conversion by acidification appeared due to destruction or loss of binding ability of the renin binding substance which was present in the cytosol of renal cortical tissue. Renin and renin binding substance could combine into HMW renin at neutral pH in the presence of thiol group blockers and renin activity decreased.