Journal ArticleDOI
Study of actin and its interactions with heavy meromyosin and the regulatory proteins by the pulse fluorimetry in polarized light of a fluorescent probe attached to an actin cysteine.
TLDR
The decay of anisotropy of the N-iodoacetyl-N'-(5-sulfo-1-naphthyl)-ethylenediamine fluorescence attached to cysteine-373 of actin can be characterized by two correlation times theta1 and theta2.Abstract:
The decay of anisotropy of the N-iodoacetyl-N'-(5-sulfo-1-naphthyl)-ethylenediamine fluorescence attached to cysteine-373 of actin can be characterized by two correlation times theta1 and theta2. theta1 has a value of several nanoseconds and is thought to represent some local protein motion. theta2 is of the order of several hundreds of nanoseconds. Its value increases with actin concentration. It represents an average of the G and F actin correlation times. When actin interacts with heavy meromyosin, theta2 increases and becomes infinite at a molar ratio of one heavy meromyosin molecule per four actin protomers. It is concluded that a definite complex is then formed between F actin and heavy meromyosin. In the same time, G actin concentration becomes equal to zero. Finally, when F actin forms a complex with the regulatory proteins tropomyosin and troponin, the value of theta2 is greater in the absence than in the presence of Ca2+. This result indicates that micromolar concentrations of Ca2+ induces a conformation change of the complex of F actin with the regulatory proteins.read more
Citations
More filters
Journal ArticleDOI
Analysis of time-resolved fluorescence anisotropy decays.
TL;DR: A new method was proposed in which parallel- and perpendicular-polarized fluorescence curves were fit simultaneously, which takes full advantage of the statistical properties of the measured curves and is shown to be more sensitive than other methods to systematic errors present in the data.
Journal ArticleDOI
Analysis of fluorescence anisotropy decays by a least square method
TL;DR: Good fitting of experimental data have been achieved very conveniently and accurately by this method, and the statistical standard errors of the anisotropy deca parameters have been found to be smaller than the standard errors previously calculated for the moment method.
Journal ArticleDOI
A fluorescent probe for conformational changes in skeletal muscle G-actin.
TL;DR: It is shown that loss of fluorescence of the labeled G-actin may be associated with inactivation of the actin and any conformational change induced by KCl is probably different from that induced by divalent metal ions.
Journal ArticleDOI
The Mg2+-induced conformational change in rabbit skeletal muscle G-actin.
TL;DR: The overall dissociation constant for Mg2+ binding is highly pH-sensitive, becoming larger with decreasing pH, implying that ionizable groups may control Mg1+ and Ca2+binding and that these cations bind preferentially to the unprotonated form.
Journal ArticleDOI
Fluorescence measurements of the binding of cations to high-affinity and low-affinity sites on ATP-G-actin.
TL;DR: It is proposed that the activation step that converts Ca-G-actin to a polymerizable species upon addition of Mg2+ is the binding of M g2+ to the low-affinity sites and not the replacement of Ca2+ by Mg 2+ at the high-affination site.
References
More filters
Journal ArticleDOI
Mouvement brownien d'un ellipsoide - I. Dispersion diélectrique pour des molécules ellipsoidales
TL;DR: Extension de la theorie du mouvement brownien de translation and de rotation au cas d'une particule ellipsoidale quelconque Application a l'etude de la dispersion dielectrique pour des molecules polaires ellipssoidales en milieu liquide I - Connaissant les coefficients de frottement de translation (f1, f2, f3 et de rotation (C1, C2, C3) relatifs, le theoreme d'equipartition de 1 energie
Journal ArticleDOI
Substructure of the myosin molecule: I. Subfragments of myosin by enzymic degradation
TL;DR: Under suitable experimental conditions, low concentrations of papain can split the enzymic globular regions of myosin from the structural α-helical rod, leaving the latter intact along its length.
Journal ArticleDOI
Synthesis and characterization of two fluorescent sulfhydryl reagents
Earl N. Hudson,Gregorio Weber +1 more
Journal ArticleDOI
Studies on the structure of myosin
TL;DR: The wide angle α -type X-ray diagram of the meromyosins, in conjunction with their hydrodynamic and rotatory dispersion properties, suggests a formal model for myosin consisting of a rod having a two-chain α -helical coiled-coil conformation, with globular portion(s) projecting from the helical core in HMM.
Related Papers (5)
The Regulation of Rabbit Skeletal Muscle Contraction I. BIOCHEMICAL STUDIES OF THE INTERACTION OF THE TROPOMYOSIN-TROPONIN COMPLEX WITH ACTIN AND THE PROTEOLYTIC FRAGMENTS OF MYOSIN
James A. Spudich,Susan Watt +1 more
Studies on the chymotryptic digestion of myosin. Effects of divalent cations on proteolytic susceptibility.
Alan G. Weeds,Brian Pope +1 more