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Carlos Gutiérrez-merino - One of the best experts on this subject based on the ideXlab platform.
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The content of Glycogen Phosphorylase and Glycogen in preparations of sarcoplasmic reticulum-Glycogenolytic complex is enhanced in diabetic rat skeletal muscle.
Diabetologia, 2001Co-Authors: E. Garduño, Carlos Gutiérrez-merino, Manuel Nogues, Jaime M. Merino, Fernando HenaoAbstract:We have examined the effect of diabetes and pharmacological insulin treatment on the content of Glycogen Phosphorylase and Glycogen associated with the sarcoplasmic reticulum–Glycogenolytic complex from rat skeletal muscle. Diabetes was induced in rats by streptozotocin injection. Enzymatic activities were measured using spectrophotometric methods. Glycogen Phosphorylase was determined measuring the pyridoxal-5' -phosphate content and using polyacrylamide gel electrophoresis. Glycogen content was measured by enzymatic and the phenol sulfuric methods. The content of Glycogen Phosphorylase associated with the sarcoplasmic reticulum Glycogenolytic complex gradually arises after diabetes induction. The content of Glycogen Phosphorylase was restored to a control value by pharmacological insulin treatment. In addition, the content of Glycogen in preparations of sarcoplasmic reticulum–Glycogenolytic complex of diabetic animals was also increased, whereas the content of Glycogen in total muscle of diabetic rats was similar to that of the control rats. The absolute and relative amount of Glycogen associated with sarcoplasmic reticulum seemed to increase in diabetic animals. These effects on the compartmentalisation of Glycogen were suppressed by insulin treatment. Additionally, the rate of conversion of Glycogen Phosphorylase b to a, an index of the Phosphorylase kinase activity, was 50 % lower in diabetic rats, increasing the dephosphorylated form of Glycogen Phosphorylase and, as a consequence, its association with sarcoplasmic reticulum membranes. These results suggest that under diabetic conditions, both Glycogen Phosphorylase and a small percentage of muscle Glycogen are relocalized in the sarcoplasmic reticulum–Glycogenolytic complex. [Diabetologia (2001) 44: 1238–1246]
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Interaction between Glycogen Phosphorylase and Sarcoplasmic Reticulum Membranes and Its Functional Implications
The Journal of biological chemistry, 1995Co-Authors: Ana Cuenda, Manuel Nogues, Fernando Henao, Carlos Gutiérrez-merinoAbstract:Abstract Skeletal muscle Glycogen Phosphorylase b binds to sarcoplasmic reticulum (SR) membranes with a dissociation constant of 1.7 ± 0.6 mg of Phosphorylase/ml at 25°C at physiological pH and ionic strength. Raising the temperature to 37°C produced a 2-3-fold decrease in the dissociation constant. The SR membranes could bind up to 1.1 ± 0.1 mg of Glycogen Phosphorylase b/mg of SR protein, whereas liposomes prepared with endogenous SR lipids and reconstituted Ca-ATPase were unable to bind Glycogen Phosphorylase. Binding of Glycogen Phosphorylase b to SR membranes is accompanied by inhibition of its activity in the presence of AMP. The Vmax for Glycogen Phosphorylase b associated with SR membranes is 40 ± 5% of that for purified Glycogen Phosphorylase and shows a decreased affinity for its allosteric activators, AMP and IMP. These kinetic effects are also observed with purified Glycogen Phosphorylase b when starch or α-amylose is used as substrate instead of Glycogen. Treatment of SR membranes with α-amylase produced dissociation of Glycogen Phosphorylase b from the SR membranes. Thus, linear polysaccharide fragments of Glycogen bound to the SR membranes are likely mediating the binding of Glycogen Phosphorylase b to these membranes.
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Differential scanning calorimetry study of Glycogen Phosphorylase b-detergent interactions.
Journal of bioenergetics and biomembranes, 1992Co-Authors: Francisco Centeno, Pedro M. Fernandez-salguero, José Laynez, Carlos Gutiérrez-merinoAbstract:The overall thermal denaturation of Glycogen Phosphorylase b is irreversible and our results conform to the theoretical prediction of a reversible process followed by a slower irreversible process. The basic thermodynamic parameters of Glycogen Phosphorylase b denaturation have been worked out and found to be: critical temperature 57.0 +/- 0.5 degrees C, transition half-width 8 +/- 1 degrees C, and calorimetric enthalpy change and Van't Hoff enthalpy change of the denaturation process 450 +/- 50 and 105 +/- 15 kcal/mol of enzyme monomer, respectively, at pH 7.4. These parameters have been found to be largely altered by the detergents octylglucoside, cholate, and deoxycholate at or below their critical micelle concentration, but not by Triton X-100 nor by lecithin liposomes. Organic solvents, such as dimethyl sulfoxide and methanol, and the presence of sarcoplasmic reticulum membranes produces an alteration of the denaturation thermogram of Glycogen Phosphorylase b similar to that produced by the above-mentioned detergents. These results allow us to hypothesize that hydrophobic domains of Glycogen Phosphorylase b are involved in its association to sarcoplasmic reticulum membranes in the sarcoplasmic reticulum/Glycogenolytic complex of mammalian skeletal muscle.
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Modulation by phosphorylation of Glycogen Phosphorylase-sarcoplasmic reticulum interaction.
FEBS letters, 1991Co-Authors: Ana Cuenda, Francisco Centeno, Carlos Gutiérrez-merinoAbstract:Abstract Glycosen Phosphorylase b at concentrations close to those found in skeletal muscle interacts with sarcoplasmic reticulum membranes, but not with liposomes made of lipids extracted from these membranes, and is inhibited upon binding to the membrane. The interaction of Glycogen Phosphorylase with the sarcoplasmic reticulum membrane is modulated by phosphorylation, for the a form of this enzyme shows a K0.5 of interaction about 10-fold lower than the b form. Upon association to the membrane the fluorescence properties of the coenzymes of Glycogen Phosphorylase, pyridoxal-5′-phosphate, are strongly altered, for the fluorescence at 535 nm is partially quenched and the fluorescence at 415–420 nm increases. Using fluorescein labeled sarcoplasmic reticulum membranes we have found that average conformation of the Ca2+ + Mg2+-ATPaze is also altered on binding or Phosphorylase b. In conclusion, the results reported in this paper suggest that Glycogen Phosphorylase and Ca2+ + Mg2+-ATPase directly interact under experimental conditions similar to those found in the sarcoplasm, and that this interaction is modulated by phosphorylation of the Phosphorylase.
Catherine Bielajew - One of the best experts on this subject based on the ideXlab platform.
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Histochemical mapping of the substrate for brain-stimulation reward with Glycogen Phosphorylase.
Journal of neuroscience methods, 1999Co-Authors: Anne T. M. Konkle, Patricia Wilson, Catherine BielajewAbstract:Glycogen Phosphorylase is the enzyme that regulates Glycogenolysis and it appears that there is a relationship between central levels of Glycogen and neuronal activity, which is influenced by a variety of neurotransmitters. In the present study, Glycogen Phosphorylase histochemistry was used to correlate changes in metabolic activity in response to rewarding lateral hypothalamic stimulation. Rats were allowed to self-stimulate for 1 h per day for ten consecutive days following which postmortem Phosphorylase a activity was examined. Significant differences in optical density between the stimulated and contralateral hemispheres were found in three of the eight analyzed structures, two of which, the diagonal band of Broca and the caudate nucleus, showed a greater density of Glycogen Phosphorylase a on the stimulated side and the third, the habenula, had greater contralateral activity. In conclusion, our data suggest that Glycogen Phosphorylase activity is a viable but not weighty marker of energy alterations induced by chronic exposure to intracranial self-stimulation, and that it is generally consistent with the patterns revealed by other metabolic indices such as cytochrome oxidase and 2-deoxyglucose autoradiography.
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A comparison of Glycogen Phosphorylase a and cytochrome oxidase histochemical staining in rat brain.
The Journal of comparative neurology, 1992Co-Authors: Carolyn A. Harley, Catherine BielajewAbstract:The utility of metabolic markers that index functional neuronal circuits is widely appreciated. The present study asks whether patterns of the metabolic enzyme, active Glycogen Phosphorylase, parallel those of the neuronal marker, cytochrome oxidase. Fresh frozen rat brain sections (30 μm) were processed for either active Glycogen Phosphorylase or cytochrome oxidase at each often levels of the neuraxis. Although these metabolic markers predominate in different cellular compartments–Glycogen Phosphorylase in the astrocytic compartment and cytochrome oxidase in the neuronal compartment–the patterns of high, moderate, and low levels of activity for both enzymes were generally parallel. These similarities extended to detailed patterns of heterogeneous staining within structures, in particular, to laminated and modular distribution within cerebral and cerebellar cortical structures. The modular distribution was evident in barrel structures in the cerebral cortex and in parasagittal compartments in the vermis of the cerebellum. Conspicuous differences between the two patterns occurred in white matter, in subcortical grey matter regions such as the nucleus accumbens, diagonal band, amygdala, and globus pallidus, and in the superior olivary nuclei of the brainstem as well as in nonneural structures such as the choroid plexus and ependyma. Discrete patchiness was characteristic of active Glycogen Phosphorylase distribution in the limbic neuropil of the dentate gyrus and entorhinal cortex. The strong parallels between active Glycogen Phosphorylase and cytochrome oxidase distribution support the view that Glycogen Phosphorylase, despite its glial localization, can reflect neuronal metabolic demands. © 1992 Wiley-Liss, Inc.
B A Kornilaev - One of the best experts on this subject based on the ideXlab platform.
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Dissociative Mechanism of Thermal Denaturation of Rabbit Skeletal Muscle Glycogen Phosphorylase b
Biochemistry, 2000Co-Authors: B A Kornilaev, Natalia A. Chebotareva, Viacheslav Malikov, Victor N. Orlov, And Arkadii E. LyubarevAbstract:The thermal stability of rabbit skeletal muscle Glycogen Phosphorylase b was characterized using enzymological inactivation studies, differential scanning calorimetry, and analytical ultracentrifugation. The results suggest that denaturation proceeds by the dissociative mechanism, i.e., it includes the step of reversible dissociation of the active dimer into inactive monomers and the following step of irreversible denaturation of the monomer. It was shown that glucose 1-phosphate (substrate), glucose (competitive inhibitor), AMP (allosteric activator), FMN, and glucose 6-phosphate (allosteric inhibitors) had a protective effect. Calorimetric study demonstrates that the cofactor of Glycogen Phosphorylase spyridoxal 5'- phosphatesstabilizes the enzyme molecule. Partial reactivation of Glycogen Phosphorylase b preheated at 53 °C occurs after cooling of the enzyme solution to 30 °C. The fact that the rate of reactivation decreases with dilution of the enzyme solution indicates association of inactive monomers into active dimers during renaturation. The allosteric inhibitor FMN enhances the rate of Phosphorylase b reactivation.
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structure regulation and denaturation of muscle Glycogen Phosphorylase b
Biochemistry, 1996Co-Authors: N B Livanova, B A KornilaevAbstract:The review summarizes data on structure, allosteric regulation, and denaturation of muscle Glycogen Phosphorylase b. Specific attention is paid to correlations between the structure and function of Phosphorylase b and molecular mechanism of its allosteric regulation. Chemical and thermal denaturation of Phosphorylase b is reviewed.
Fernando Henao - One of the best experts on this subject based on the ideXlab platform.
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The content of Glycogen Phosphorylase and Glycogen in preparations of sarcoplasmic reticulum-Glycogenolytic complex is enhanced in diabetic rat skeletal muscle.
Diabetologia, 2001Co-Authors: E. Garduño, Carlos Gutiérrez-merino, Manuel Nogues, Jaime M. Merino, Fernando HenaoAbstract:We have examined the effect of diabetes and pharmacological insulin treatment on the content of Glycogen Phosphorylase and Glycogen associated with the sarcoplasmic reticulum–Glycogenolytic complex from rat skeletal muscle. Diabetes was induced in rats by streptozotocin injection. Enzymatic activities were measured using spectrophotometric methods. Glycogen Phosphorylase was determined measuring the pyridoxal-5' -phosphate content and using polyacrylamide gel electrophoresis. Glycogen content was measured by enzymatic and the phenol sulfuric methods. The content of Glycogen Phosphorylase associated with the sarcoplasmic reticulum Glycogenolytic complex gradually arises after diabetes induction. The content of Glycogen Phosphorylase was restored to a control value by pharmacological insulin treatment. In addition, the content of Glycogen in preparations of sarcoplasmic reticulum–Glycogenolytic complex of diabetic animals was also increased, whereas the content of Glycogen in total muscle of diabetic rats was similar to that of the control rats. The absolute and relative amount of Glycogen associated with sarcoplasmic reticulum seemed to increase in diabetic animals. These effects on the compartmentalisation of Glycogen were suppressed by insulin treatment. Additionally, the rate of conversion of Glycogen Phosphorylase b to a, an index of the Phosphorylase kinase activity, was 50 % lower in diabetic rats, increasing the dephosphorylated form of Glycogen Phosphorylase and, as a consequence, its association with sarcoplasmic reticulum membranes. These results suggest that under diabetic conditions, both Glycogen Phosphorylase and a small percentage of muscle Glycogen are relocalized in the sarcoplasmic reticulum–Glycogenolytic complex. [Diabetologia (2001) 44: 1238–1246]
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Interaction between Glycogen Phosphorylase and Sarcoplasmic Reticulum Membranes and Its Functional Implications
The Journal of biological chemistry, 1995Co-Authors: Ana Cuenda, Manuel Nogues, Fernando Henao, Carlos Gutiérrez-merinoAbstract:Abstract Skeletal muscle Glycogen Phosphorylase b binds to sarcoplasmic reticulum (SR) membranes with a dissociation constant of 1.7 ± 0.6 mg of Phosphorylase/ml at 25°C at physiological pH and ionic strength. Raising the temperature to 37°C produced a 2-3-fold decrease in the dissociation constant. The SR membranes could bind up to 1.1 ± 0.1 mg of Glycogen Phosphorylase b/mg of SR protein, whereas liposomes prepared with endogenous SR lipids and reconstituted Ca-ATPase were unable to bind Glycogen Phosphorylase. Binding of Glycogen Phosphorylase b to SR membranes is accompanied by inhibition of its activity in the presence of AMP. The Vmax for Glycogen Phosphorylase b associated with SR membranes is 40 ± 5% of that for purified Glycogen Phosphorylase and shows a decreased affinity for its allosteric activators, AMP and IMP. These kinetic effects are also observed with purified Glycogen Phosphorylase b when starch or α-amylose is used as substrate instead of Glycogen. Treatment of SR membranes with α-amylase produced dissociation of Glycogen Phosphorylase b from the SR membranes. Thus, linear polysaccharide fragments of Glycogen bound to the SR membranes are likely mediating the binding of Glycogen Phosphorylase b to these membranes.
James G. Tidball - One of the best experts on this subject based on the ideXlab platform.
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Identification of a putative collagen-binding protein from chicken skeletal muscle as Glycogen Phosphorylase
Biochimica et biophysica acta, 1992Co-Authors: Douglas J. Law, James G. TidballAbstract:We have purified and generated antisera to 1 95 kDa skeletal muscle protein that constitutes the largest mass fraction of gelatin-agarose binding proteins in skeletal muscle. Preliminary results indicated that this 95 kDa chicken skeletal muscle protein bound strongly to gelatin-agarose and type IV collagen-agarose, suggesting a possible function in muscle cell adhesion to collagen. However, N-terminal sequencing of proteolytic fragments of the 95 kDa protein indicates that it is the chicken skeletal muscle form of Glycogen Phosphorylase, the binding of which to gelatin-agarose is unlikely to be biologically relevant. Further characterization showed that the skeletal muscle form of Glycogen Phosphorylase is immunologically distinct from the liver and brain forms in the chicken, and suggests that, unlike mammalian skeletal muscle, chicken skeletal muscle may have two phosphorylate isoforms. Furthermore, immunolocalization data and solubility characteristics of Glycogen Phosphorylase in muscle extraction experiments suggest the enzyme may interact strongly with an unidentified component of the muscle cytoskeleton. Thus, this study yields a novel purification technique for skeletal muscle Glycogen Phosphorylase, provides new information on the distribution and isoforms of Glycogen Phosphorylase, and provides a caveat for using gelatin affinity chromatography as a primary step in purifying collagen-binding proteins from skeletal muscle.