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In the presence of the nucleotide analog adenosine 5'-[gamma-thio]triphosphate (ATP[gamma S]), effects of Ca2+ on stiffness and equatorial x-ray diffraction patterns of single skinned fibers of the rabbit psoas muscle were studied. It is shown that cross-bridges in the presence of ATP[gamma S] have properties of the weak-binding states of the ATP hydrolysis cycle. Raising the Ca2+ concentration up to pCa 4.5 has little effect on actin affinity of cross-bridges in the presence of ATP[gamma S]. However, the rate constants for cross-bridge dissociation and reassociation from and to actin are reduced by about 2 orders of magnitude. In addition, nucleotide affinity of the cross-bridge is much smaller at high Ca2+ concentrations. Implications for interpretation of fiber stiffness recorded during isotonic shortening and the rising phase of a tetanus are discussed.
T Kraft, and
L C Yu, and
H J Kuhn, and
B Brenner
November 1988,
Biochemistry,
T Kraft, and
L C Yu, and
H J Kuhn, and
B Brenner
January 1984,
Acta biochimica et biophysica; Academiae Scientiarum Hungaricae,
T Kraft, and
L C Yu, and
H J Kuhn, and
B Brenner
September 1973,
Biochemistry,
T Kraft, and
L C Yu, and
H J Kuhn, and
B Brenner
January 1988,
Methods in enzymology,
T Kraft, and
L C Yu, and
H J Kuhn, and
B Brenner
January 1991,
Journal of biochemistry,
T Kraft, and
L C Yu, and
H J Kuhn, and
B Brenner
June 1953,
Biochimica et biophysica acta,
T Kraft, and
L C Yu, and
H J Kuhn, and
B Brenner
August 1975,
Biochemistry,
T Kraft, and
L C Yu, and
H J Kuhn, and
B Brenner
February 1962,
Biochimica et biophysica acta,
T Kraft, and
L C Yu, and
H J Kuhn, and
B Brenner
April 1974,
FEBS letters,
T Kraft, and
L C Yu, and
H J Kuhn, and
B Brenner
January 1996,
Journal of bacteriology,
