Comparative properties of glycogen phosphorylase. VIII. Phosphorylase from dogfish skeletal muscle. Purification and a comparison of its physical properties to those of rabbit muscle phosphorylase

Biochemistry ◽  
1971 ◽  
Vol 10 (14) ◽  
pp. 2683-2694 ◽  
Author(s):  
Philip Cohen ◽  
Theresa Duewer ◽  
Edmond H. Fischer
Keyword(s):  
Skeletal Muscle ◽  
Physical Properties ◽  
Glycogen Phosphorylase ◽  
Rabbit Muscle ◽  
Muscle Phosphorylase

Fish muscle glycogen phosphorylase

1968 ◽  
Vol 46 (5) ◽  
pp. 423-432 ◽  
Author(s):  
M. Yamamoto
Keyword(s):  
Skeletal Muscle ◽  
Glycogen Phosphorylase ◽  
Active Form ◽  
Maximal Activity ◽  
Fish Muscle ◽  
Salmo Gairdneri ◽  
Rabbit Muscle ◽  
Muscle Phosphorylase

Glycogen phosphorylase b was purified 70- to 90-fold from skeletal muscle of rainbow trout (Salmo gairdneri). The purified enzyme exhibited maximal activity near pH 6.8 at 37°. Of several 5′-nucleotides tested, only 5′-AMP caused stimulation of phosphorylase b. The Km value for glucose-1-phosphate was 10–15 mM, and for 5′-AMP, 0.2–0.4 mM. Glucose (25 mM) and ATP (5 mM) were both inhibitory, but glucose-6-phosphate (5 mM) had no effect. Inactive trout muscle phosphorylase was converted to the active form in vivo by subjecting a fish to physical exercise. The conversion of fish muscle phosphorylase b to a was also catalyzed in vitro with purified rabbit muscle phosphorylase b kinase in the presence of ATP and Mg++. Evidence is presented to indicate the presence of phosphorylase b kinase and phosphorylase phosphatase in trout skeletal muscle.

The sulfhydryl groups of muscle phosphorylase. V. The reactive sulfhydryl peptides

1970 ◽  
Vol 48 (7) ◽  
pp. 763-775 ◽  
Author(s):  
C. G. Zarkadas ◽  
L. B. Smillie ◽  
N. B. Madsen
Keyword(s):  
Skeletal Muscle ◽  
Molecular Weight ◽  
Muscle Glycogen ◽  
Glycogen Phosphorylase ◽  
Chromatographic Purification ◽  
Model Compounds ◽  
Rate Of Reaction ◽  
Peptic Digestion ◽  
Muscle Phosphorylase ◽  
Column Chromatographic

Skeletal muscle glycogen phosphorylase a and b have previously been shown to consist of four and two subunits, respectively, each having a molecular weight of 92 500. Our studies have indicated that there is a minimum of eight and a maximum of nine unique cysteine sequences in the enzyme providing additional evidence that the subunits are identical. From the known sequences of the nine sulfhydryl peptides it was possible to isolate and characterize the reactive sulfhydryl peptides of phosphorylase. Careful column chromatographic purification of alkylated peptides derived from peptic digestion showed that there are two cysteine residues per monomer of phosphorylase b whose rate of reaction with iodoacetamide approaches that of model compounds and whose alkylation does not affect significantly the enzymic properties of the protein. These two cysteines have been identified in sequences corresponding to numbers 2 and 5 previously elucidated. These sequences have been extended in the present work and may now be written as: No. 2 Asn–Gln–Lys–Ile–CMC–Gly–Gly–Try–Gln–Ser, and No. 5 Gly–CMC–Arg–Asp–Pro–Val–Arg–Thr–Asn–Phe.

scholarly journals Effect of denervation on the expression of glycogen phosphorylase in mouse skeletal muscle

1990 ◽  
Vol 272 (1) ◽  
pp. 231-237 ◽  
Author(s):  
D M Leyland ◽  
P C Turner ◽  
R J Beynon
Keyword(s):  
Skeletal Muscle ◽  
Glycogen Phosphorylase ◽  
Specific Activity ◽  
Muscular Atrophy ◽  
Cdna Probe ◽  
Rapid Decline ◽  
Mrna Levels ◽  
Control Muscle ◽  
Muscle Phosphorylase

After sciatectomy of the left hind-limb of C57BL/J mice, a denervation-induced muscular atrophy ensued and was accompanied by a decrease in the specific activity of glycogen phosphorylase to approx. 25% of control values. The cofactor of phosphorylase, pyridoxal 5′-phosphate, was used as a specific label in the determination of the degradation rate of the enzyme following nerve section. After a delay of 3-4 days, phosphorylase was degraded approx, twice as rapidly in the denervated gastrocnemius (0.20 day-1) as in the control muscle (0.12 day-1). The effect of denervation on phosphorylase mRNA was measured by quantitative Northern-blot analysis using a rat skeletal-muscle phosphorylase cDNA probe. After an initial rapid decline, phosphorylase mRNA levels stabilized in denervated muscle at 50% of the value measured in the contralateral control muscle.

Fluorescence Quenching, a Tool for Probing Conformational Changes in Glycogen Phosphorylase

1973 ◽  
Vol 51 (4) ◽  
pp. 344-356 ◽  
Author(s):  
K. O. Honikel ◽  
N. B. Madsen
Keyword(s):  
Fluorescence Quenching ◽  
Conformational Changes ◽  
Glycogen Phosphorylase ◽  
Pyridoxal Phosphate ◽  
Catalytic Mechanism ◽  
Fluorescence Emission ◽  
Ring Structure ◽  
Rabbit Muscle ◽  
Quenching Rate ◽  
Muscle Phosphorylase

This study shows that conformational changes in glycogen phosphorylase are accompanied by changes in the accessibility of tryptophan residues and of the coenzyme, pyridoxal phosphate, to the surrounding aqueous medium. The accessibility was estimated by determining the extent to which iodide can quench the fluorescence emission of these moieties by colliding with them, since iodide cannot collide with a buried chromophore and hence cannot quench its fluorescence. Rabbit muscle phosphorylase b, its apoform, and phosphorylase a exhibit differences in the number of exposed tryptophans, while the phosphorylase b forms from rabbit skeletal muscle and pig heart also show differences.Differences are also observed in the accessibility of the coenzyme in different forms of the enzyme. The quenching rate constant, a measure of accessibility, differs for phosphorylases a and b, and this constant is affected differently by ligand binding to the two forms. While the allosteric inhibitors, ATP and glucose 6-phosphate, render the pyridoxal phosphate moiety of phosphorylase b more accessible, the activator, AMP, and substrate, glucose 1-phosphate, together cause it to be totally inaccessible to fluorescence quenching by iodide. AMP and glucose 1-phosphate appear to mediate a conformational change which buries the coenzyme. While pyridoxal phosphate is necessary for catalytic activity, one may conclude from these experiments that its ring structure is unlikely to participate directly in the catalytic mechanism.

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