Multicatalytic proteinase activity in turtle liver: responses to anoxia stress and recovery.
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.
Willmore
W G
WG
Institute of Biochemistry, Carleton University, Ottawa, Ontario, Canada.
Storey
K B
KB
D000332:Aerobiosis; D000595:Amino Acid Sequence; D000818:Animals; D002384:Catalysis; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D004734:Energy Metabolism; D006706:Homeostasis; D000860:Hypoxia / Q000201:enzymology*; D008099:Liver / Q000201:enzymology*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009097:Multienzyme Complexes / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex; D014176:Protein Biosynthesis; D011506:Proteins / Q000378:metabolism*; D013312:Stress, Physiological / Q000201:enzymology*; D014426:Turtles / Q000378:metabolism*
D009097:Multienzyme Complexes; D011506:Proteins; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex