Role of tetramer ⇆ dimer equilibrium in the dephosphorylation and activity of phosphorylase a

G. Bot, E. Kovacs, P. Gergely

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Abstract

Skeletal muscle phsophorylase a exists as a tetramer or a dimer depending upon the temperature and protein concentration. The rate of dephosphorylation by phosphorylase phosphatase is very low at 18° C where phosphorylase a exists as a tetramer. Caffeine markedly increases the rate of dephosphorylation of tetrameric phosphorylase a at 18° C but has no effect on the dephosphorylation of the dimeric form. Caffeine also enhances the enzymic activity of phosphorylase a at 18° C. The results presented here indicate that caffeine can shift the tetramer ⇆ dimer equilibrium toward the dimeric form at 18° C. This conclusion is supported by sedimentation analyses.

Original languageEnglish
Pages (from-to)335-341
Number of pages7
JournalActa biologica Academiae Scientiarum Hungaricae
Volume12
Issue number4
Publication statusPublished - Jan 1 1977

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ASJC Scopus subject areas

  • Agricultural and Biological Sciences(all)

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