Cell Language Theory, The: Connecting Mind And Matter

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“6x9” b2861 The Cell Language Theory: Connecting Mind and Matter

Fig

ure 3.48

Simultaneous measurements of the mechanical movement of the myosin head and the associated kinetics of ATP hydrolysis.

Reproduced from [232, 233] with modification: I added the star symbol, *, to myosin in State (3) to indicate the presence of

conformational

strains

or

the conformons postulated to be stored

in myosin. (a) In the presence of ATP, a molecule of myosin head immobilized on a block

exerts a force on an actin filament attached to two beads on its ends. One of these beads is fixed with a laser tweezers and the movement of the other is measured with another optical tweezers. (b) An alternative way of measuring the myosin’s mechanical activity. The myosin molecule attached to the tip of a micro-needle is brought to an actin filament fixed on a glass surface so that it can touch actin molecules. Given ATP in the medium, the myosin head exerts a force on the actin filament, thereby producing an equal and opposite force on the tip of the micro-needle (following the Third Law of Newtonian mechanics), which causes the micro-needle to undergo displacements as recorded in (c). (c) Expanding the rising phase of the step movement revealed substeps of 5.5 nm, the diameter of the actin monomer. (d) The results of a simultaneous measurement of the mechanical movement of the myosin head and the hydrolysis of one molecule of a fluorescent ATP analog. The upper trace records the movement of myosin along the actin filament and the lower trace shows the binding activity of ATP to myosin. The high level of fluorescence indicates the binding of a molecule of ATP to the myosin head and the low level of fluorescence signals the desorption of ATP and ADP from myosin. It should be noted here that the superscript * added to the myosin head in state (3) (to denote the conformationally strained and hence mechanically energized state of the myosin head) is a modification proposed in [25, p. 374] for the first time based on the conformon theory of molecular machines [6, 12, 143–145].

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