pH-dependent rate of formation of the gelsolin-actin complex from gelsolin and monomeric actin.
The assembly of gelsolin with actin was followed by the increase of the fluorescence intensity of a fluorescence label bound to actin. The time course of the formation of the gelsolin-actin complex in the presence of micromolar [Ca2+] could be quantitatively interpreted by a model in which one actin molecule binds slowly to gelsolin in a rate-determining step and subsequently a second actin molecule is bound at least 40 times more rapidly. The rate of binding of the first actin molecule to gelsolin was found to be remarkably slow and to depend on the pH. The rate constants of formation of the gelsolin-actin complex range from 1.5 X 10(4) M-1 s-1 at pH 8 to 7 X 10(4) M-1 s-1 at pH 6.
Selve
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Institut für Physiologische Chemie, Ruhr-Universität Bochum, Federal Republic of Germany.
Wegner
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A
D000199:Actins / Q000378:metabolism*; D001665:Binding Sites / Q000187:drug effects; D001792:Blood Platelets / Q000378:metabolism*; D002118:Calcium / Q000494:pharmacology; D002135:Calcium-Binding Proteins / Q000378:metabolism*; D004533:Egtazic Acid / Q000494:pharmacology; D018260:Gelsolin; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008433:Mathematics; D008840:Microfilament Proteins / Q000378:metabolism*; D011485:Protein Binding; D013050:Spectrometry, Fluorescence
D000199:Actins; D002135:Calcium-Binding Proteins; D018260:Gelsolin; D008840:Microfilament Proteins; D004533:Egtazic Acid; D002118:Calcium