The effect of dicyclohexycarbodiimide and cyclopiazonic acid on the difference FTIR spectra of sarcoplasmic reticulum induced by photolysis of caged-ATP and caged-Ca2+

Rene Buchet, Istvan Jona, Anthony Martonosi

Research output: Contribution to journalArticle

23 Citations (Scopus)

Abstract

The photochemical release of Ca2+ from caged-Ca2+ in the absence of ATP, and the release of ATP from caged-ATP in the presence of Ca2+ induce characteristic difference FTIR spectra on rabbit sarcoplasmic reticulum that are related to the formation of Ca2E1 and E ∼ P intermediates of the Ca2+-ATPase, respectively. Dicyclohexylcarbodiimide (10 nmol/mg protein) abolished both the Ca2+-and ATP-induced difference FTIR spectra parallel with inhibition of ATPase activity. Cyclopiazonic acid (50 nmol/mg protein) inhibited the Ca2+-induced difference spectrum measured in the absence of ATP, but had no significant effect on the ATP-induced difference spectrum measured in the presence of 1 mM Ca2+. The dog kidney Na+,K+-ATPase did not give significant difference spectrum after photolysis of caged-ATP in Ca2+-free media containing 90 mM Na+ and 10 mM K+, with or without ouabain. We propose that both the Ca2+ and the ATP-induced difference FTIR spectra of the Ca2+-ATPase reflect the occupancy of the high-affinity Ca2+ transport site of the enzyme.

Original languageEnglish
Pages (from-to)207-214
Number of pages8
JournalBBA - Biomembranes
Volume1104
Issue number1
DOIs
Publication statusPublished - Feb 17 1992

Keywords

  • ATPase, Ca-
  • Caged ATP
  • Caged calcium
  • FTIR
  • Photolysis
  • Sarcoplasmic reticulum

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Cell Biology

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