The stiffness of the crossbridge is a function of the intrinsic protein osmotic pressure generated by the crossbridge itself.
A model is presented that makes it possible to determine the stiffness of the crossbridge from protein osmotic stress experiments. The model was elaborated while studying the osmotic properties of F-actin and of myosin subfragment-1 F-actin. These studies showed that the elastic modulus by bending of the monomer is directly related to the intrinsic protein osmotic pressure of the system. At a protein osmotic pressure of 1.8 x 10(5) dynes/cm2, the physiological protein osmotic pressure of frog skeletal muscle, it was found that the elastic moduli by bending of the monomer in F-actin and in the myosin subfragment-1 decorated F-actin are 6.5 X 10(7) and 3.3 X 10(8) dynes/cm2, respectively. The value of the elastic modulus by bending of the monomer in the myosin subfragment-1 decorated F-actin compares favorably with the values of the elastic modulus by stretching determined in skeletal muscle fibres.
Grazi
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E
Dipartimento di Biochimica e Biologia Molecolare, Università di Ferrara, Italy.
Magri
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E
Schwienbacher
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C
Trombetta
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G
D000199:Actins / Q000737:chemistry*; D008432:Mathematical Computing; D008956:Models, Chemical; D008958:Models, Molecular; D015879:Myosin Subfragments / Q000737:chemistry*; D009997:Osmotic Pressure; D014867:Water / Q000737:chemistry
D000199:Actins; D015879:Myosin Subfragments; D014867:Water