Effect of dithiothreitol of the reaction of renin and angiotensinogen.

Effects of several sulfhydryl reagents on the reaction of renin and angiotensinogen were investigated by measuring the production of angiotensin I. Renin and angiotensinogen were prepared from the kidneys of dogs and from plasma of nephrectomized dogs, respectively. The amount of angiotensin I generated was increased with application of dithiothreitol, dithioerythritol and 2,3-mercapto-1-propanol. The greatest enhancement of the generation of angiotensin I was observed with dithiothreitol. Dithiothreitol had no influence on renin activity, on radioimmunoassay for angiotensin I and the recovery of synthetic angiotensin I from the incubation medium. When heterologous angiotensinogen was used, a great enhancement of generation of angiotensin I was observed. Dithiothreitol did not accelerate the reaction following replacement of the natural substrate, angiotensinogen, with the synthetic tetradecapeptide as substrate. It is postulated that dithiothreitol augments angiotensin I generation by acting on the angiotensinogen and not on the renin.