Effects of anoxia on protein phosphatase in turtle organs: purification and properties of protein phosphatase type-1 from turtle liver.
Protein phosphatase type 1 (PP-1) was analyzed in organs of the red-eared slider turtle, Trachemys scripta elegans, a species capable of long-term anoxia survival. During anoxic submergence at 7 degrees C, PP-1 activity in liver rapidly decreased to 63% of the control value within the first hour and remained suppressed over the subsequent 20 h of anoxia. PP-1 activity was also suppressed in red skeletal muscle during anoxia and dropped transiently (after 1 h) in brain but did not change in heart or white muscle. PP-1 was purified from turtle liver using polyethylene glycol fractionation and chromatography on DEAE-cellulose, blue dextran, Sephacryl S-200, and ADP-agarose. A 3000-fold purification was achieved with a final specific activity of 3156 nmol released min-1 mg protein-1 using 32P-labeled phosphorylase a as the substrate. Turtle liver PP-1 was a monomer of molecular mass 37 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis or 38 +/- 2 kDa by Sephacryl S-200 gel filtration. The enzyme was inhibited by okadaic acid (Ki 12.6 +/- 1.4 nM) and AMP (Ki 23 +/- 2 microM) as well as by ADP, ATP, and IMP. Regulation of liver PP-1 appears to be an integral part of anoxia-induced changes in liver glycogenolysis and metabolic rate suppression.
Mehrani
H
H
Institute of Biochemistry, Carleton University, Ottawa, Ontario, Canada.
Storey
K B
KB
D000249:Adenosine Monophosphate / Q000494:pharmacology; D000818:Animals; D001921:Brain / Q000201:enzymology / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D004988:Ethers, Cyclic / Q000494:pharmacology; D006321:Heart / Q000502:physiology; D000860:Hypoxia / Q000378:metabolism*; D008099:Liver / Q000201:enzymology / Q000502:physiology*; D018482:Muscle, Skeletal / Q000201:enzymology / Q000502:physiology; D009206:Myocardium / Q000201:enzymology; D019319:Okadaic Acid; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors / Q000187:drug effects / Q000302:isolation & purification / Q000378:metabolism*; D014018:Tissue Distribution; D014426:Turtles / Q000502:physiology*
D004988:Ethers, Cyclic; D019319:Okadaic Acid; D000249:Adenosine Monophosphate; D010749:Phosphoprotein Phosphatases