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Radiochemical Assessment of Glycogen Synthase Enzyme Activity in Animal Tissue
02:30

Radiochemical Assessment of Glycogen Synthase Enzyme Activity in Animal Tissue

Published on: October 24, 2025

211

Photocleavage of muscle glycogen phosphorylase by vanadate

C M Bergamini1, M Signorini

  • 1Istituto di Chimica Biologica dell'Università, Ferrara, Italy.

Biochemistry International
|September 1, 1991
PubMed

Insights

Near UV light degrades glycogen phosphorylase in the presence of vanadate. Monovanadate causes less protein cleavage than decavanadate, releasing an N-terminal peptide.

Area of Science:

  • Biochemistry
  • Photochemistry
  • Enzymology

Background:

  • Glycogen phosphorylase is a key enzyme in glycogen metabolism.
  • Vanadate is known to interact with various enzymes.
  • Near UV irradiation can induce photochemical reactions.

Purpose of the Study:

  • To investigate the effect of near UV light and vanadate on glycogen phosphorylase.
  • To characterize the cleavage pattern of glycogen phosphorylase under these conditions.

Main Methods:

  • Irradiation of glycogen phosphorylase with near UV light in the presence of monovanadate and decavanadate.
  • Analysis of protein cleavage products using peptide mapping.

Main Results:

  • Glycogen phosphorylase undergoes progressive degradation upon irradiation with near UV light and vanadate.
  • Monovanadate induces fewer peptide fragments compared to decavanadate.
  • Cleavage is ligand-dependent, with an initial 82,000-dalton peptide released, containing the N-terminal portion and phosphorylation site.

Conclusions:

  • Vanadate, in conjunction with near UV light, can lead to specific degradation of glycogen phosphorylase.
  • The differential cleavage patterns suggest distinct mechanisms of action for monovanadate and decavanadate.
  • The identified N-terminal peptide fragment provides insights into the enzyme's structure and regulation.

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