Spectrofluorimetric studies on C-terminal 34 kDa fragment of caldesmon
| Autor: | Eugene A. Permyakov, Victor I. Emelyanenko, Edward A. Czuryło, Renata Dabrowska |
|---|---|
| Rok vydání: | 1991 |
| Předmět: |
animal structures
Calmodulin Protein Conformation Stereochemistry Biophysics Fluorescence spectrometry Tropomyosin Biochemistry Animals Bound water biology Chemistry Binding protein Organic Chemistry Temperature Tryptophan musculoskeletal system Fluorescence Caldesmon Spectrometry Fluorescence biology.protein Calmodulin-Binding Proteins Chickens Protein Binding |
| Zdroj: | Biophysical Chemistry. 40:181-188 |
| ISSN: | 0301-4622 |
| DOI: | 10.1016/0301-4622(91)87007-r |
| Popis: | Analysis of the tryptophan fluorescence emission spectra of caldesmon and its 34 kDa C-terminal fragment indicates that all tryptophan residues are located on the surface of the molecule, accessible to solvent. All three tryptophan residues of the 34 kDa fragment and four of the five tryptophan residues of intact potein are accessible to free water, whereas one located in the N -terminal region of molecule is accessible only to bound water molecules. The temperature dependence of the fluorescence parameters indicates higher thermal stability of the 34 kDa fragment than the whole caldesmon molecule. The interaction of the 34 kDa fragment of caldesmon (like that of the intact molecule) with calmodulin is accompanied by a blue shift of the fluorescence emission maximum and an increase in the relative quantum yield. Computer-calculated binding constants show that the binding of calmodulin to the 34 kDa fragment ( K = 2.5·10 5 M −1 ) is of two orders of magnitude weaker than that to intact caldesmon ( K = 1.4·10 7 M −1 ). The interaction with tropomyosin results in a blue shift of the spectrum of the 34 kDa fragment, yet there is no effect on the spectrum of intact caldesmon. Binding constants of tropomyosin to caldesmon ( K = 3.8·10 5 M −1 ) and its 34 kDa fragment ( K = 2.3·10 5 M −1 ) are similar. Binding of calmodulin to caldesmon and to the 34 kDa fragment affects their interaction with tropomyosin. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|