[The identification of Ca2+-dependent nucleases activated in the nuclei of rat thymocytes under the action of glucocorticoids].

Spectra of thymocyte's nuclear nucleases of control and glucocorticoid treated (5 mg/kg body weight) adrenalectomized rats have been investigated. Using the method of SDS-electrophoresis of nuclear proteins in 3H-DNA-polyacrylamide gel (PAAG) the authors managed to discover a number of polypeptides of 35, 32, 17.7, 17.0, 16.4 kDa molecular mass possessing a nuclease activity. The enzyme of 35 kDa is only active in the presence of Ca2+ and Mg2+ ions and inhibited by cycloheximide. Nucleases of 32, 17.7, 17.0, 16.4 kDa are active in the presence of Ca2+ ions. The enzymic activity of these nucleases increases 60 min after steroid treatment. Nuclease of 17.7, 17.0, 16.4 kDa are poly(ADP-ribosylated). Glucocorticoid mediated activation don't blocked by poly(ADP-ribosylation). Possible role and mechanism of discovered nucleases are discussed.