sup 19 F NMR study of the myosin and tropomyosin binding sites on actin

Journal Article · Tue Feb 06 04:00:00 EST 1990 · Biochemistry; (USA)

DOI:https://doi.org/10.1021/bi00457a034· OSTI ID:6718462

Barden, J A; Phillips, L ^[1]

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1. Univ. of Sydney (Australia)

Actin was labeled with pentafluorophenyl isothiocyanate at Lys-61. The label was sufficiently small not to affect the rate or extent of actin polymerization unlike the much larger fluorescein 5-isothiocyanate which completely inhibits actin polymerization. Furthermore, the label resonances in the 376.3-MHz {sup 19}F NMR spectrum were unaffected by actin polymerization. However, the binding of the relaxing protein tropomyosin resulted in the fluorinated Lys-61 resonances broadening out beyond detection due to a substantial increase in the effective correlation time of the label. Similarly, the binding of myosin subfragment 1 to F-actin resulted in the dramatic broadening of the labeled Lys-61 resonances. Thus, Lys-61 on actin appears to be closely associated with the binding sites for both tropomyosin and myosin, suggesting that both these proteins can compete for the same site on actin. The other region of actin known to be involved in myosin binding, Cys-10, was found to be more remote from the actin-actin interfaces than Lys-61. Labels on Cys-10 exhibited substantially greater mobility than fluorescein 5-isothiocyanate attached to Lys-61 which appeared to be held down on the surface of the actin monomer. This may sterically hinder the actin-actin interaction about 1 nm from the tropomyosin/myosin binding site.

• OSTI ID: 6718462
• Journal Information: Biochemistry; (USA), Journal Name: Biochemistry; (USA) Vol. 29:5; ISSN 0006-2960; ISSN BICHA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ACTIN
AMINO ACIDS
AROMATICS
BARYONS
CARBOXYLIC ACIDS
CHEMICAL REACTIONS
CROSS-LINKING
DYES
ELEMENTARY PARTICLES
FERMIONS
FLUORESCEIN
FLUORINE 19
FLUORINE ISOTOPES
GLOBULINS
HADRONS
HYDROXY ACIDS
HYDROXY COMPOUNDS
ISOTHIOCYANATES
ISOTOPES
LIGHT NUCLEI
LYSINE
MAGNETIC RESONANCE
MYOSIN
NMR SPECTRA
NUCLEAR MAGNETIC RESONANCE
NUCLEI
NUCLEONS
ODD-EVEN NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
PHENOLS
POLYMERIZATION
POLYPHENOLS
PROTEINS
PROTONS
RESONANCE
SPECTRA
STABLE ISOTOPES
TROPOMYOSIN