Renin granules isolated from rat kidney cortex by continuous colloidal silica (Percoll) density gradient centrifugation.

Renin granules were isolated from rat kidney cortex by a continuous polyvinyl-pyrrolidone-coated colloidal silica (Percoll) density gradient centrifugation. A major peak of renin activity was found at a density of 1.12-1.13 g/ml, and the specific activity of renin in the peak fraction was increased by approximately 70-fold, as compared with that in the kidney cortex homogenate. On the other hand, activities of other reference enzymes, such as succinate dehydrogenase, acid phosphatase and glucose-6-phosphatase, were not detectable in the peak fraction. When the extract of the peak fraction was applied to a pepstatin column, trypsin-activated renin could not be detected in the breakthrough fractions. These results indicate that renin granules of the rat kidney cortex contain only active renin.