Effects of disulphides and α-oxoglutarate on nuclear thiol formation and thiol content of chromatin in lysed rat spleen nuclei

Abstract

1. 1. During incubation of lysed rat spleen nuclei, there was a noted increase in total SH, accompanied by a slight decrease of chromatin SH and a more pronounced increase in SH of the non-sedimentable fraction. 2. 2. During incubation, chromatin nucleolytic cleavage was completely inhibited by 1 mM cystamine and 1 mM oxidized glutathione (GSSG). 3. 3. In nucleus lysates, glutathione reductase activity dependent on NADPH, and disulphide reductase NADH-dependent reducing disulphides of the non-sedimentable fraction, but not affecting GSSG, were demonstrated. 4. 4. In the presence of 1 mM GSSG there was a transfer of SH from the non-sedimentable fraction to the rat spleen chromatin, while 1 mM 6,8-thioctic acid exerted an opposite effect. Cystamine (1 mM) was found to decrease SH content of either chromatin and the non-sedimentable fraction. 5. 5. Reduced glutathione (GSH) and cysteamine (MEA) and CoA did not change chromatin SH. 6. 6. In the presence of α-oxoglutarate, as in the presence of GSSG, an increase in chromatin SH was found, indicating the role of dihydrolipoate in the control of chromatin SH level.