Heterogeneity of renin

Renin is an aspartyl protease mainly synthesized in juxtaglomerular cells, located in the glomerular afferent arteriole in the kidney and released into the blood stream. Despite numerous attempts to purify the angiotensin converting enzyme from the kidney, the complete isolation of pure and stable renal renin from the kidney proved to be most, difficult due to its extremely low concentration and rapid inactivation by co-eluted proteases. One of the important and interesting characteristics of renin is its heterogeneity. Generally, renin has a molecular weight of around 40000, but renin with a molecular weight over 40000 has been found in plasma, amniotic fluid, and kidney in many species. The fractions containing renin eluted with the same buffer were pooled, concentrated, adjusted to pH 4.5 by ultrafiltration with 0.01 M Na-acetate buffer, and centrifuged at 3000 rpm for 10 min.