PMID: 9546679Apr 18, 1998Paper

Tryptophan mutants of troponin C from skeletal muscle--an optical probe of the regulatory domain

European Journal of Biochemistry
M SheH C Cheung

Abstract

We have generated a series of chicken skeletal muscle troponin C mutants to study the conformation of the regulatory domain in the N-terminal half of the molecule. These mutants each contained a single Trp at position 22 (helix A), 52 (linker of helices B and C), or 90 (central helix). Some of these mutants also contained additional mutations to introduce a single Cys at a desired position. The mutants were characterized by molecular graphics and CD and found to have a minimum of structural perturbations when compared with the native structure. They also retained the ability to regulate myofibrillar ATPase activity. The fluorescence of Trp22 was sensitive to Ca2+ binding only to the regulatory sites, whereas Trp52 and Trp90 responded to Ca2+ binding to both the regulatory and the Ca2+/Mg2+ sites. The tryptophan quantum yield (Q) of all Trp22-containing mutants was very high (0.33) in the absence of bound Ca2+, compared to that of L-tryptophan in aqueous solution (0.14). Q decreased 25% upon binding of Ca2+ to the regulatory sites. The quantum yields of Trp52 and Trp90 in apo mutants were close to 0.14. In the presence of bound Ca2+ at the regulatory sites, the quantum yield of Trp52 decreased 16%, whereas that of Trp90 increase...Continue Reading

Citations

Sep 20, 2002·Proceedings of the National Academy of Sciences of the United States of America·Louise J BrownPiotr G Fajer
Mar 27, 2001·Protein Science : a Publication of the Protein Society·K ZhuP K Kinnunen
Oct 19, 2004·Biochimica Et Biophysica Acta·Arimatti JutilaPaavo K J Kinnunen
Sep 4, 2007·FASEB Journal : Official Publication of the Federation of American Societies for Experimental Biology·Jeffrey F BreitMark N Gillespie
Jan 5, 2017·The Journal of Biological Chemistry·Mayra de A MarquesGuilherme A P de Oliveira
Oct 25, 2002·The Journal of Biological Chemistry·Jonathan P DavisSvetlana B Tikunova
Jan 4, 2003·The Journal of Biological Chemistry·Wen-Ji DongHerbert C Cheung
Feb 7, 2021·The Journal of Biological Chemistry·Kaveh RayaniGlen F Tibbits

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