The role of magnesium in muscle phosphorylase kinase activity

Linda B. Clerch, F. Huijing

Research output: Contribution to journalArticle

20 Citations (Scopus)

Abstract

Phosphorylase kinase (ATP:phosphorylase phosphotransferase, EC 2.7.1.38), the enzyme which regulates glycogen breakdown by converting α-glucan phosphorylase (α-1,4-glucan:orthophosphate glucosyltransferase, EC 2.4.1.1) into its active form, requires ATP and divalent metal ions for its activity. We have shown that: 1. 1.MgATP2-2 chelate is the substrate for the reaction with an apparent Km of 0.07 mM ± 0.02 (S.D.). 2. 2.Free Mg2+ in mM concentration is also required for activity. The apparent Ka for free Mg2+ is 0.6 mM ± 0.2 (S.D.). 3. 3.Free ATP4- is not inhibitory. 4. 4.Mn and Ca at mM concentrations are inhibitors of the enzyme even though μM concentrations of Ca are required for activity1,2. With both metals the inhibition is not competitive with respect to MgATP2- and Mg2+. Mn as well as Al, Ba and Co, in the absence of Mg, will allow the phosphorylase kinase reaction to proceed but only at approx. 5% of the rate observed in the presence of Mg.

Original languageEnglish
Pages (from-to)654-662
Number of pages9
JournalBBA - Enzymology
Volume268
Issue number3
DOIs
StatePublished - Jun 16 1972
Externally publishedYes

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Phosphorylase Kinase
Phosphorylases
Magnesium
Metals
Glucosyltransferases
Muscles
Enzyme Inhibitors
Glycogen
Phosphotransferases
Adenosine Triphosphate
Phosphates
Ions
Enzymes
Arabidopsis PHS2 protein
1,4-glucan

ASJC Scopus subject areas

  • Medicine(all)

Cite this

The role of magnesium in muscle phosphorylase kinase activity. / Clerch, Linda B.; Huijing, F.

In: BBA - Enzymology, Vol. 268, No. 3, 16.06.1972, p. 654-662.

Research output: Contribution to journalArticle

Clerch, Linda B. ; Huijing, F. / The role of magnesium in muscle phosphorylase kinase activity. In: BBA - Enzymology. 1972 ; Vol. 268, No. 3. pp. 654-662.
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