Kidney secretes an enzyme, which changes plasma protein angiotensinogen into angiotensin. The enzyme is

The kidney plays a critical role in blood pressure regulation through the Renin-Angiotensin-Aldosterone System (RAAS). When renal perfusion or sodium levels decrease, the juxtaglomerular cells of the kidney secrete the enzyme renin into the bloodstream [3]. Renin acts as an aspartyl-protease that catalyzes the cleavage of the plasma protein angiotensinogen, which is primarily synthesized in the liver, to form the decapeptide angiotensin I [4]. This is the rate-limiting step of the RAAS pathway [3]. Subsequently, angiotensin-converting enzyme (ACE), found primarily in the lungs and kidney vascular epithelium, converts angiotensin I into the active hormone angiotensin II [3]. While other enzymes like nitrogenase are involved in plant nitrogen fixation [5] and hydrolases catalyze bond cleavage, renin is the specific enzyme secreted by the kidney for this hormonal conversion [3].

Sources

1. [3] https://www.ncbi.nlm.nih.gov/books/NBK470410/
2. [1] https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/angiotensinogen
3. [4] https://pmc.ncbi.nlm.nih.gov/articles/PMC4137912/
4. [5] Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 25: Agriculture > Nitrogen (N) > p. 363
5. [2] https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/orange-g