IN-VITRO ACTIVATION OF THE 20S PROTEASOME

The effect of chemical compounds like sodium dodecyl sulfate (SDS), fa tty acid esters of glycerol, carnitine and coenzyme A, phospholipids, histones, polylysines as well as homobifunctional chemical cross-linke rs on the various proteolytic activities of mammalian proteasomes have been tested. Most of the reagents enhance these activities, and some, e.g. fatty acid CoA esters, histones and the chemical cross-linkers, exert dual effects, i.e. activation and inhibition at the same time, d epending on the activity measured. With optimally activating concentra tions of SDS, no structural changes in proteasomes can be detected by electron microscopy. Formation of micelles at supra-optimal detergent concentrations may be a reason for irreversible denaturation of the pr oteasome.