Denisty labelling characterisation of the effects of cordycepin and cycloheximide on the turnover of phenylalanine ammonia-lyase

Christopher John Lamb, Michael Andrew Lawton, Susan Elizabeth Shields

Research output: Contribution to journalArticlepeer-review

5 Scopus citations

Abstract

l-Phenylalanine ammonia-lyase (EC 4.31.5) undergoes a transient increase in activity in illuminated discs of Solanum tuberosum tuber parenchyme. Cycloheximide and cordycepin inhibit the initial increase in enzyme activity, but if addition of these anti-metabolites is delayed until the time of maximum enzyme levels, the subsequent decline in enzyme activity is inhibited (Lamb, C.J. (1977) Planta, 135, 169-175). The effect of delayed treatment with cycloheximide or cordycepin on the turnover of phenylalanine ammonia-lyase has been analysed by density labelling with 2H from 2H2O. Delayed introduction of cycloheximide or cordycepin reduces the rate of labelling of phenylalanine ammonia-lyase whilst preventing the decay in enzyme activity observed in controls not treated with inhibitor, and this labelling pattern cannot be accounted for by effects of cycloheximide or cordecypin on the labelling of amino acid pools. It is concluded that delayed treatment with cycloheximide or cordycepin leads to the maintenance of high levels of phenylalanine ammonia-lyase by inhibition of the removal of active enzyme rather than by maintenance of high rates of enzyme synthesis.

Original languageEnglish (US)
Pages (from-to)1-8
Number of pages8
JournalBBA - General Subjects
Volume675
Issue number1
DOIs
StatePublished - Jun 11 1981
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Biophysics
  • Biochemistry
  • Molecular Biology

Keywords

  • (Solanum tuberosum)
  • Cordycepin
  • Cycloheximide
  • Density labelling
  • Enzyme Turnover
  • Phenylalanine ammonia-lyase

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