Tension generation by threads of contractile proteins.
Open Access
- 31 December 1976
- journal article
- research article
- Published by Rockefeller University Press in The Journal of general physiology
- Vol. 69 (1), 37-55
- https://doi.org/10.1085/jgp.69.1.37
Abstract
Threads of contractile proteins were formed via extrusion and their isometric tensions and isotonic contraction velocities were measured. We obtained reproducible data by using a new and sensitive tensiometer. The force-velocity curves of actomyosin threads were similar to those of muscle, with isometric tensions of the order of 10g/cm2 and maximum contraction velocites of the order of 10(-2) lengths/s. The data could be fitted by Hill's equation. Addition of tropomyosin and troponin to the threads increased isometric tension and maximum contraction velocity. Threads which contained troponin and tropomyosin required Ca++ for contraction and the dependence of their isometric tension on the level of free Ca++ was like that of muscle. The dependence of tension or of contraction velocity upon temperature or upon ionic strength is similar for actomyosin threads and muscle fibers. In contrast, the dependence of most parameters which are characteristic of the actomyosin interaction in solution (or suspension) upon these variables is not similar to the dependence of the muscle fiber parameters. The conclusion we have drawn from these results is that the mechanism of tension generation in the threads is similar to the mechanism that exists in muscle. Because the protein composition of the thread system can be manipulated readily and because the tensions and velocities of the threads can be related directly to the physiological parameters of muscle fibers, the threads provide a powerful method for studying contractile proteins.This publication has 27 references indexed in Scilit:
- Methodology for in vitro studies of Ca2+ transportAnalytical Biochemistry, 1975
- A new method for producing myosin subfragment-1Biochemical and Biophysical Research Communications, 1972
- 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.1971
- Reconstitution of Troponin Activity from Three Protein ComponentsJournal of Biological Chemistry, 1971
- Native tropomyosin: Effect on the interaction of actin with heavy meromyosin and subfragment-1Biochemical and Biophysical Research Communications, 1970
- Adenosine Triphosphatase Activity and Superprecipitation of Canine Cardiac Myosin B*The Journal of Biochemistry, 1967
- ATPase Activity of Myosin Correlated with Speed of Muscle ShorteningThe Journal of general physiology, 1967
- The dependence of contraction and relaxation of muscle fibres from the crab Maia squinado on the internal concentration of free calcium ionsBiochimica et Biophysica Acta (BBA) - Specialized Section on Biophysical Subjects, 1964
- The spontaneous transformation reactions of myosinBiochimica et Biophysica Acta, 1961
- PROTEIN MEASUREMENT WITH THE FOLIN PHENOL REAGENTJournal of Biological Chemistry, 1951