McClare's Quantum Mechanical Muscle Model

• Published in: Nature (London) 1973-01, Vol.242 (5398), p.473-474
• Main Authors: BANKS, BARBARA E. C., CALLOMON, J. H., VERNON, C. A.
• Format: Article
• Language: English
• Subjects: Humanities and Social Sciences; letter; multidisciplinary; Science
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/242473b0

STARTING from the belief that the “energy” for muscular contraction is derived from the “energy” released by the hydrolysis of ATP, McClare 1 has concluded that this “energy” must initially be stored in individual molecules of ATP. The amount of “energy” so stored is supposed to equal the enthalpy change for the hydrolysis of ATP (presumably in its ground state), at p H 7.4. A considerable part of the quoted figure (−40 kJ mol −1 ) is, in fact, due to the heat of neutralization of a proton which is formed in near stoichiometric amount at this p H (refs. 2, 3). Nevertheless, McClare proposes that the total enthalpy change is somehow trapped in the other two products of hydrolysis, ADP and inorganic phosphate, which subsequently exist in an excited “state”, out of thermal equilibrium with surrounding molecules for a significant time. A calculation then shows that the wavelength of radiation having energy equivalent to this enthalpy change is 3 µm, which lies in the infrared. McClare concludes from this that the “energy” is stored (in ADP and inorganic phosphate) in a vibrational mode. The lifetime of a vibrational excited state is quoted as being ca . 10 −7 s.