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.
|Number of pages||7|
|Journal||Acta biologica Academiae Scientiarum Hungaricae|
|Publication status||Published - Jan 1 1977|
ASJC Scopus subject areas
- Agricultural and Biological Sciences(all)