Differential inhibition of Pi-ATP exchange in relation to ATP synthesis and hydrolysis by modification of chloroplast thylakoid membranes with glutaraldehyde

Dudy Bar-Zvi, Noun Shavit

Research output: Contribution to journalArticlepeer-review

3 Scopus citations

Abstract

Limited modification of thylakoid membranes with glutaraldehyde inhibits the Pi-ATP exchange reaction much more than ATP synthesis or hydrolysis. More extensive modification of the membranes results in the inhibition of all activities of the ATP synthetase, but does not affect electron transport. Limited modification also does not have much effect on the tight binding of [3H]ADP or the ΔpH supported by ATP hydrolysis. The modification affects the catalytic process itself and not the activation of the latent enzyme. Cross-linking between thylakoid polypeptides is observed only after extensive treatment with glutaraldehyde, while limited modification does not result in cross-linking between polypeptides. The differential inhibition of the Pi-ATP exchange relative to ATP hydrolysis can be explained by the decrease in only one of the kinetic rate constants involved in these reactions. However, the relative insensitivity of photophosphorylation to the modification suggests that different enzyme conformations may participate in phosphorylation (light) and ATP hydrolysis or Pi-ATP exchange (dark).

Original languageEnglish
Pages (from-to)299-308
JournalBiochimica et Biophysica Acta - Bioenergetics
Volume724
Issue number3
DOIs
StatePublished - 30 Sep 1983

Keywords

  • ATPase
  • Chemical modification
  • Glutaraldehyde
  • P-ATP exchange
  • Photophosphorylation
  • Thylakoid modification

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Cell Biology

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