Molecular motion and cardiac muscle motor dynamics.
This paper reports on the kinetics of molecular motion in cardiac (and skeletal) muscles, studied by image analysis of the motility assay of an isolated actin filament sliding over isolated myosin heads that perform as linear motors. Image analysis allows us to study the dynamics of the crossbridges (Xbs) formed by the interactions between the actin molecule and the myosin heads, and to explore the rate kinetics of the interactions between the two. A most significant result pertains to the identification and characterization of two kinds of kinetics involved in Xb dynamics. The analysis of the acquired images suggests that Xb dynamics is determined by two distinctive kinetic mechanisms: fast physical kinetics that relates to the actin-myosin Xb attachment and detachment cycle and a process that is orders of magnitude slower in biochemical kinetics that relates to the reactions of nucleotide binding and dissociation.
Landesberg
Amir
A
Department of Biomedical Engineering, Technion, Israel Institute of Technology, Haifa, Israel. amir@biomed.technion.ac.il
Landesberg
Yolanda
Y
Sideman
Samuel
S
Ter Keurs
Henk E D J
HE
D000199:Actins / Q000378:metabolism; D000818:Animals; D006321:Heart / Q000502:physiology*; D007091:Image Processing, Computer-Assisted; D007700:Kinetics; D020409:Molecular Motor Proteins / Q000502:physiology*; D009206:Myocardium / Q000378:metabolism*; D009218:Myosins / Q000378:metabolism; D010210:Papillary Muscles / Q000502:physiology*; D012984:Software
D000199:Actins; D020409:Molecular Motor Proteins; D009218:Myosins