Intermonomer flexibility of Ca- and Mg-actin filaments at different pH values

Research output: Contribution to journalArticle

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Abstract

The fluorescence resonance energy transfer parameter, f, is defined as the efficiency of the energy transfer normalized by the quantum yield of the donor in the presence of acceptor. It is possible to characterize the flexibility of the protein matrix between the appropriate fluorescent probes by monitoring the temperature dependence of f. The intermonomer flexibility of the Ca-actin and Mg-actin filaments was characterized by using this method at pH values of 6.5 and 7.4. The protomers were labeled on Cys374 with donor [N-(((iodoacetyl)amino)ethyl)-5-naphthylamine-1-sulfonate; IAEDANS] or acceptor [5-(iodoacetamido)fluorescein; IAF] molecules. The temperature profile of f suggested that the intermonomer flexibility of actin filaments was larger at pH 7.4 than pH 6.5 in the case of Mg-F-actin while this difference was absent in the case of Ca-F-actin. More rigid intermonomer connection was identified at both pH values between the protomers of Mg-F-actin compared to the Ca-F-actin. The results were further supported by time dependent fluorescence measurements made on IAEDANS and IAF labeled Mg- and Ca-actin filaments at pH 6.5 and 7.4. Our spectroscopic results may suggest that the altered function of muscle following the change of pH within the muscle cells under physiological or pathological conditions might be affected by the modified dynamic properties of the magnesium saturated actin filaments. The change of the intracellular pH does not have an effect on the intermonomer flexibility of the Ca-actin filaments.

Original languageEnglish
Pages (from-to)842-849
Number of pages8
JournalEuropean Journal of Biochemistry
Volume269
Issue number3
DOIs
Publication statusPublished - 2002

Fingerprint

Actin Cytoskeleton
Actins
Protein Subunits
1-Naphthylamine
Fluorescence Resonance Energy Transfer
Muscle
Temperature
Energy Transfer
Fluorescent Dyes
Muscle Cells
Magnesium
Fluorescence
Quantum yield
Energy transfer
Muscles
Cells
Molecules
Proteins
Monitoring

Keywords

  • Cations
  • Fluorescence anisotropy decay
  • Fluorescence resonance energy transfer
  • Muscle
  • Protein dynamics

ASJC Scopus subject areas

  • Biochemistry

Cite this

Intermonomer flexibility of Ca- and Mg-actin filaments at different pH values. / Hild, G.; Nyitrai, M.; Somogyi, B.

In: European Journal of Biochemistry, Vol. 269, No. 3, 2002, p. 842-849.

Research output: Contribution to journalArticle

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