Rotors elasticity

This is a special form of pump in which a length of silicone rubber or other elastic tubing, typically of 3 to 25 mm diameter, is compressed in stages by means of a rotor as shown in Figure 8.11. The tubing is fitted to a curved track mounted concentrically with a rotor... 

I. Elastic scattering of ground state para- and ortho-H2 in the rigid rotor approximation. J. Chem. Phys., 70 344, 1979. 

Curve 1 in Fig. 1 under low rotor r.p.m. corresponds to the case when the rate of the stress buildup under the effect of deformation is commensurate with the rate of their relaxation. The development of time-delayed elastic deformations determines the final rate of attainment of the steady-state regime of viscous flow, under which the stationary value of the shear stress is recorded. Starting with the moment of time t, the stress will increase and the period of the viscous-plastic state comes to an end. 

Table 14.11 gives the density, tensile strength, and modulus of elasticity E of six possible high-tensile materials for centrifuge rotors. These properties are given in metric units and SI units. 

Thus the fundamental predictions of the hydrophobic elastic consilient mechanism are that the rotor would exhibit asymmetric hydrophobicity, that different arrangements of nucleotide analogues representing different states of polarity at the catalytic sites would orient the rotor, and that hydrolysis of ATP in formation of the most polar state at a catalytic site of the involved protein subunit(s) would demonstrate a near-ideal elastic deformation of the y-rotor and the protein subunit(s). Of course, such a mechanism would exhibit high efficiency and reversibility. 

Prediction of Hydrophobically Asymmetric and Elastically Deformable Rotor and Housing... 

Demonstrations of these predictions constitute the message of this section 8.4, and its success introduces the perspective of a conjoined hydrophobic elastic consilient mechanism. With the values in Table 5.3 and the crystal structure with three different states of occupancy, empty, ATP, and ADP, the three sides of the rotor can be identified and the respective Gibbs free energies of hydrophobic association, AGha, have been estimated to be -20, 0, and +9kcal/mole. The most hydrophobic face associates with the empty site, the neutral face with the ATP bound site, and the most polar face with the ADP site which in the synthesis mode would be in position to add Pj. As expected from the magnitude of the resulting AG,p for a series of crystal structures wherein the least polar occupancy state for the catalytic site could be defined, the most hydrophobic side of the rotor resides in apposition to the least polar site. 

AGap available to the Fi-motor, that is, a near maximal apolar-polar repulsive free energy of hydration between the hydrophobic side of the y-rotor and the very polar state, ADP -i- SO , of a catalytic P-subunit. This near-maximal repulsion provides an elastic deformation of rotor and housing as required for efficient function of the ATPase in its performance of chemo-mechanical transduction. 

The rotor that is driven by the Fo-motor comprises a single y-subunit and a small e-subunit attached to the y-subunit at a point proximal to the base of the Fo-motor. This is called the y-rotor. In the hydrophobic elastic consilient mechanism, the interactions of a hydrophobi-cally asymmetric y-rotor with the housing of the Fi-motor with different occupancy states of the catalytic sites constitute the basis for mechano-chemical transduction of the Fi-motor. 

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