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Muscle contraction and enzymatic action: Challenges to quantum chemistry
Author(s) -
Bennett H. Stanley
Publication year - 1981
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.560200729
Subject(s) - chemistry , myosin , atp hydrolysis , muscle contraction , biophysics , contraction (grammar) , actin , atomic orbital , electron , biochemistry , enzyme , anatomy , physics , atpase , biology , quantum mechanics , endocrinology
The energy of muscle contraction is generated by interactions between the proteins actin and myosin, acting together to hydrolyze a metaphosphate bond of ATP in the presence of Mg ++ , using the oxygen of a specific water molecule. The molecular setting for these events is described. A key feature is identified to be an attack by the water oxygen on one of the POP bonds. The resulting hydrolysis liberates a phosphate group which is forcefully repelled from its original setting, perturbing metal ions and electron orbitals in the vicinity. The hypothesis is advanced that the accompanying perturbations excite an electron cloud to a hgher energy level, leading to a forceful expansion of the electron cloud. A model is presented representing the S‐l head of myosin as being tilted with reference to the coordinates of the actin filament by the expansion of this cloud. This tilt represents a leverlike movement of the S‐1 myosin head which is capable of powering the work of muscle contraction. Since the most important molecular participants in muscle contraction are present in all cells, the issues raised here are of very general biological significance.