Activities of the multicatalytic proteinase complex (MPC) were detected in turtle (Trachemys scripta elegans) liver. The ratio of peptidylglutamyl-peptide bond hydrolyzing, trypsin-like, and chymotrypsin-like activities was 6:2.7:1 for the MPC partially purified by Sepharose CL-6B gel filtration. Molecular mass of the turtle liver enzyme was 940 ± 46 kD. Nondenaturing PAGE revealed a single band containing MPC activity reacting with peptide substrate. In vivo anoxia exposure (20 h submergence in N2-bubbled water) and subsequent 24 h aerobic recovery stimulated changes in liver protease activity. Peptidylglutamyl-peptide bond hydrolyzing activity of the partially purified MPC increased by 29% during aerobic recovery. Elevated MPC activity during recovery may serve to catabolize specific stress-related proteins or to remove proteins damaged by oxygen free radicals generated upon the reintroduction of oxygen.

Anoxia tolerance, Extralysosomal proteolysis, Intracellular protein turnover, Metabolic arrest, Trachemys scripta, Turtle hepatic protein catabolism
Biochemistry and Molecular Biology International
Department of Biology

Willmore, W, & Storey, K. (1996). Multicatalytic proteinase activity in turtle liver: Responses to anoxia stress and recovery. Biochemistry and Molecular Biology International, 38(3), 445–451.