Alteration of the intramolecular dynamics of glycogen phosphorylase b by allosteric ligands

Á Szarka, E. Gabellieri, M. Gonnelli, P. Cioni, Zs Lakos, B. Somogyi

Research output: Contribution to journalArticle

5 Citations (Scopus)


Phosphorylase b (E.C., prepared from rabbit skeletal muscle, was used to study whether the binding of allosteric ligands modifies the intramolecular dynamics of the protein matrix. Protein dynamics were monitored through the fluorescence and phosphorescence parameters of the 12 tryptophan (Trp) residues (one monomer) of the enzyme. The phosphorescence lifetime was measured at room temperature both in the absence and the presence of ligands. The addition of an allosteric inhibitor (ATP) decreased the lifetime, while the presence of activator (AMP) and/or substrate (G-1-P) had no detectable effect. The lifetime data allow us to conclude that the environment of the buried tryptophans becomes more flexible upon the binding of ATP, while the other ligands did nor induce such change. The ATP-induced perturbation was also examined by the quenching of Trp fluorescence by acrylamide. The quenching parameters did not show any change, suggesting that the effect of ATP is localized to the vicinity of the phosphorescent Trp residues.

Original languageEnglish
Pages (from-to)52-56
Number of pages5
JournalJournal of Photochemistry and Photobiology B: Biology
Issue number1
Publication statusPublished - Jan 1 1998


  • Conformational changes
  • Fluorescence
  • Glycogen phosphorylase
  • Room-temperature phosphorescence

ASJC Scopus subject areas

  • Radiation
  • Radiological and Ultrasound Technology
  • Biophysics
  • Radiology Nuclear Medicine and imaging

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