CHEMISTRY OF NATURAL COMPOUNDS AND BIOORGANIC CHEMISTRY - RADIATION-INDUCED INACTIVATION OF ANGIOTENSIN-CONVERTING ENZYME IN AQUEOUS-SOLUTIONS .1. THE EFFECT OF IRRADIATION CONDITIONS

Radiation-induced inactivation of angiotensin-converting enzyme (ACE) was studied. The relationship of this process to damage to aromatic amino acid residues (tyrosine and tryptophan) was demonstrated by the method of second derivatives of UV spectra. In some cases, the dependence of inactivation on dose had an induction period. The comparison of the radiation-induced inactivation parameters of ACE, serine proteinases, and horseradish peroxidase points to a significant stabilizing effect of carbohydrate residues in glycoproteins (''autoprotective mechanism''). At pH 7.5, conformational changes occur in ACE. Low accessibility of the active center of this enzyme was suggested.