Distinct amp binding sites in glycogen phosphorylase b as revealed by calorimetric studies

Wang, Jerry Hsueh-ching; Kwok, Siu-Chun; Wirch, Erwin; Suzuki, Isamu

doi:10.1016/0006-291x(70)90013-6

Cited by 44 publications

(15 citation statements)

References 9 publications

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“…This result is in agreement with previous findings on the activation and/or dissociation of GPa tetramers or AMP-activated G P b tetramers by glycogen and other polysaccharides (Wang et al, 1965a(Wang et al, , 1970Metzger et ai., 1967;Graves et al, 1968a;Huang & Graves, 1970). The effect of maltohexaose (or maltoheptaose) on GPb activation, in the presence of 0.9 M ammonium sulfate and 1 mM AMP, was also studied.…”

Section: Properties Of Tetrameric Gpb In Solutionsupporting

confidence: 94%

Kinetic properties of tetrameric glycogen phosphorylase b in solution and in the crystalline state

et al. 1992

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Section: Properties Of Tetrameric Gpb In Solutionsupporting

confidence: 94%

Kinetic properties of tetrameric glycogen phosphorylase b in solution and in the crystalline state

et al. 1992

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“…Phosphorylase b has been shown by several groups of workers to bind two molecules of AMP per dimer with Kd about 100pM (Seery & Anderson, 1972;Brooks et al, 1974;Griffiths et al, 1976). Wang et al (1970) also found that the enzyme binds additional molecules of AMP with Kd about 3mm. The latter binding sites were also confirmed by equilibrium studies (Morange et al, 1976).…”

Section: Discussionmentioning

confidence: 93%

Interaction of phosphorylase b with eosin. Influence of substrate and effectors on eosin-enzyme complexes

Oikonomakos¹,

Sotiroudis²,

Evangelopoulos³

1979

Biochemical Journal

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The interactions of rabbit muscle glycogen phosphorylase b with Eosin (2',4',5',7'-tetrabromofluorescein) was studied. Eosin was found to be an effective inhibitor of the enzyme. The inhibition constants for the dye were estimated to be approx. 36 and 60 microM with respect to AMP and glucose 1-phosphate respectively. The binding of Eosin to phosphorylase b is accompanied by a red-shift of about 12 nm in the dye absorption-spectrum maximum, indicating low-polarity binding sites on the enzyme molecule for the dye. The absorbance in the difference absorption maximum at 537 nm was utilized to follow the conjugation of phosphorylase b with Eosin. Scatchard plots of the titration data revealed the existence of at least two classes of binding sites on the protein molecule for Eosin, and the dissociation constants measured in Tris/HCl buffer, pH 7.0 (IO.091), were 7.7 and 41.7 microM respectively. The influence of the substrates and effectors on Eosin-enzymes complexes was used to study the ligand-phosphorylase b interactions. IMP displaced the dye completely from the enzyme, indicating that there are two IMP-binding sites per phosphorylase b monomer. AMP binding to the enzyme with respect to Eosin concentration is of two types: a non-competitive one for the high-affinity site for AMP and a competitive one for the low-affinity site for the activator. The effects of glucose 6-phosphate, ATP, Pi and glycerol 2-phosphate in the system are in according dance with a partially competitive model. Glucoes 1-phosphate and UDP-glucose appear to affect only the high-affinity site for Eosin, whereas glucose and glycogen have no effect on Eosin-phosphorylase b complexes. Our results suggest that Eosin can be used as an efficient optical probe for studying the phosphorylase b system.

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“…Later investigations [Wang et al, 1970;Merino et al, 1977] showed the existence of two binding sites of the effector by monomer, the allosteric, N site, located on the protein interface monomers and a second binding site, referred to by Johnson et al [1978] as site I and located on the protein surface.…”

Section: Introductionmentioning

confidence: 99%

Comparative Study of the Interactions AMP-Phosphorylase b and AMP Analogues-Phosphorylase b

Amat¹,

Palou²,

F³

1985

Enzyme

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The different effects induced by AMP and its analogues on the tertiary structure and the coenzyme environment of phosphorylase b were studied by titration of the slowly reacting thiol groups and by quenching of the coenzyme fluorescence, respectively, to determine the possible differences that activate phosphorylase b. The following results were obtained: (1) The coenzyme environment depends upon the nucleotide studied. AMP, when bound to its first site, opens the coenzyme pocket. (2) The slow cysteines were shielded by the nucleotides against their DTNB titration depending on the nucleotide studied. (3) The enzyme difference spectra in presence of the nucleotide showed that the negative band of 260 nm is similar for all nucleotides possessing the same base, but the positive band obtained in the presence of AMP was diminished when other nucleotides were present.

show abstract

Distinct amp binding sites in glycogen phosphorylase b as revealed by calorimetric studies

Cited by 44 publications

References 9 publications

Kinetic properties of tetrameric glycogen phosphorylase b in solution and in the crystalline state

Kinetic properties of tetrameric glycogen phosphorylase b in solution and in the crystalline state

Interaction of phosphorylase b with eosin. Influence of substrate and effectors on eosin-enzyme complexes

Comparative Study of the Interactions AMP-Phosphorylase b and AMP Analogues-Phosphorylase b

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