Evidence for a posttranslational covalent modification of liver glyceraldehyde-3-phosphate dehydrogenase in hibernating jerboa (Jaculus orientalis) |
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| Institution: | 1. Laboratoire de Biochimie, Biologie Cellulaire et Moléculaire, Faculté de Sciences-Ain Chock, BP 5366 Maarif, Casablanca, Morocco;2. Instituto de Bioquímica Vegetal y Fotosíntesis, Consejo Superior de Inuestigaciones Científicas y Universidad de Seuilla, Apdo. 1113, 41080-Sevilla, Spain;1. Faculté de médecine Paris-Diderot, UMR-S1144, 10, avenue de Verdun, 75010 Paris, France;2. Service de médecine interne A, clinique thérapeutique, hôpital Lariboisière, AP–HP, 2, rue Ambroise-Paré, 75010 Paris, France;1. Ningbo Institute of Materials Technology & Engineering, Chinese Academy of Sciences, Ningbo, 315201, PR China;2. University of Chinese Academy of Sciences, Beijing, 100049, PR China;3. Southern University of Science and Technology of China, Shenzhen, 518055, PR China;1. State Key Lab of Fine Chemicals, Liaoning Key Lab for Energy Materials and Chemical Engineering, PSU-DUT Joint Center for Energy Research, School of Chemical Engineering, Dalian University of Technology, Dalian 116024, China;2. School of Chemistry, Dalian University of Technology, Dalian 116024, China;1. Department of Physics, E.R.K. Arts and Science College, Erumiyampatti, Dharmapuri, 636 905, Tamil Nadu, India;2. Department of Physics, Periyar University, Salem, 636 011, Tamil Nadu, India;3. Department of Energy Science, Periyar University, Salem, 636 011, Tamil Nadu, India;1. Laboratory of Physiopathology, Molecular Genetics & Biotechnology, Faculty of Sciences Ain Chock, Health and Biotechnology Research Centre, Hassan II University of Casablanca, Maarif, B.P 5366, Casablanca, Morocco;2. Department of Food Science, University of Agricultural Science and Veterinary Medicine, 3-5 Calea M?n??tur, 400372, Cluj-Napoca, Romania;3. Molecular Nutrition and Proteomics Lab, CDS3, Life Science Institute, University of Agricultural Sciences and Veterinary Medicine, Calea M?n??tur 3-5, 400372, Cluj-Napoca, Romania;4. Food Biotechnology and Molecular Gastronomy, CDS7, Life Science Institute, University of Agricultural Science and Veterinary Medicine, Calea M?n??tur 3-5, 400372, Cluj-Napoca, Romania |
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| Abstract: | The specific activity of d-glyceraldehyde-3-phosphate (G3P) dehydrogenase (phosphorylating) (GPDH, EC 1.2.1.12) found in liver of induced hibernating jerboa (Jaculus orientalis) was 2–3-fold lower than in the euthermic animal. However, the comparative analysis of the soluble protein fraction of these tissues by SDS-PAGE and Western blotting showed no significant changes in the intensity of the 36 kDa protein band of the GPDH subunit. After using the same purification procedure, the GPDH from liver of hibernating jerboa exhibited lower values for both apparent optimal temperature and specific activity than the enzyme from the euthermic animal. Similar non-linear Arrhenius plots were obtained, but the Ea values calculated for the GPDH from hibernating tissue were higher. Although in both purified enzyme preparations four isoelectric GPDH isoforms were resolved by chromatofocusing, those of hibernating liver exhibited more acidic pI values (pI 7.3–6.1) than the hepatic isoforms of euthermic animals (pI 8.7–8.1). However, all liver GPDH isoforms exhibited similar native and subunit molecular masses and cross-reacted with an antibody raised against muscle GPDH. The comparison of the kinetic parameters of both purified preparations and the main isoforms isolated from euthermic and hibernating tissues showed the decreased catalytic efficiency of hibernating enzyme being exclusively due to a lower Vmax for both substrates G3P and NAD+. Phosphodiesterase treatment of cell-free extracts increased GPDH activity in the case of hibernating liver only. The pI of the main isoform purified from this tissue, about 6.9, changed after this treatment to an alkaline value (pI 8.44) similar to those of the euthermic GPDH isoforms. Differential ultraviolet absorption spectra of these isoforms indicated that a substance absorbing at 260 nm, that was released by the phosphodiesterase digestion, was present in the enzyme of hibernating tissue. Incubation of purified GPDH with the NO-releasing agent sodium nitroprussite produced under conditions that promote mono-ADP-ribosylation a dramatic decrease of activity (up to 60%) of both euthermic and phosphodiesterase-treated hibernating preparations but only a marginal inhibition of the hibernating enzyme. These data suggest that liver GPDH of hibernating jerboa exhibits a posttranslational covalent modification, being probably a mono-ADP-ribosylation. The resulting inhibition of enzyme activity could contribute to the wide depression of the glycolytic metabolic flow associated with mammalian hibernation. |
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