Ultraviolet spectroscopy of renin

• 1.1. Experimental evidence has been presented to demonstrate the existence of the renin-protein complex in three distinct configurations which can be distinguished by ultraviolet spectroscopy.
• 2.2. Conditions have been established which induce the spontaneous and reversible transformation of renin into these three configurations.
• 3.3. Identical transformation reactions have not been observed under these conditions in other proteolytic enzymes such as pepsin, trypsin, and chymotrypsin, and they cannot be induced in other proteins extracted from kidney tissue.
• 4.4. The interpretation of the experimental results has been complicated by the susceptibility of highly purified renin to inactivation.
• 5.5. Transformation and inactivation of renin are not interrelated; they constitute independent processes. Reversible transformation into the three configurations can still be induced in renin preparations which are enzymatically inactive.
• 6.6. The transformation of renin as demonstrated by ultraviolet spectroscopy appears to be a reversible process, probably not of a hydrolytic nature, in contrast to the conversion of chymotrypsin previously described.
• 7.7. Tyrosine and tryptophan contents of purified renin preparations have been calculated from spectroscopic data. Other factors, in addition to the concentration of these amino acids, have been shown to affect the ultraviolet-light absorption of renin to a very pronounced degree.