RENEWAL OF DNA IN NON-DIVIDING CELLS AND AGEING

The investigations concerning the values of the free NH2 and COOH functional groups of dried protein resulted from the blood serum of rats of various ages, point out that the number of free anainic and carboxylic groups diminishes in course of the ageing processes, and especially that of the NH2 groups is significant (P < 0.01). The old animals (rats) submitted to a Folcysteine-Oeriu treatment present an increase of free aminic and carboxylic groups of their dried protein, in comparison with the values found in the control old ones (untreated rats). The increase of the free aminic groups is especially noteworthy (P < 0.01). We suggest that the metabolic alterations of -SH substances, characterized by an accumulation of disulphide groups (-SS-) in course of the ageing processes, lead to protein modifications. Under the action of Folcysteine-Oeriu which sets free in the organism, by enzymatic route, the activated -SH groups, we find a tendency for the giant protein molecules to split into smaller ones, proper to younger organisms.