Elastic-contractile model proteins elasticity

A diverse set of energy conversions that sustain life can be experimentally demonstrated by de novo design of elastic-contractile model proteins under the precept of a single, pervasive, mechanism, that is, by a consilient mechanism that creates a common groundwork of explanation. It is a mechanism that achieves function by controlling association of... 

Based on a series of designed elastic-contractile model proteins. Figure 1.2 exhibits a family of curves whereby stepwise linear increases in oil-like character give rise to supra-linear increases in curve steepness, that is, in positive cooperativity. More oil-like phenylalanine (Phe, F) residues with the side chain -CH2-C6H5 replace less oil-like valine (Val, V) residues with the side chain -CH-(CH3)2. Here the structural symmetry is translational with as many as 42 repeats (Model protein v) of the basic 30-residue sequence, and the structure is designed beginning with a repeating five-residue sequence of a fibrous protein, the mam-mahan elastic fiber. 

Figure 1.3. A Hill plot of the set of designed elastic-contractile model proteins shown in Figure 1.2 with Hill coefficients, n, ranging from 1.5 to 8.0. B Hill plot of myoglobin (n = 1) and hemoglobin (n = 2.8). It is shown that the vaunted hemoglobin positive cooperativity is relatively small compared with that of designed elastic protein-based polymers and, in particular, of designed Model protein v.

Most significantly, however, the molecular basis for positive cooperativity and the result of increased functional efficiency in designed elastic-contractile model proteins has been experimentally determined to be the competition for water that occurs between oil-like domains and charged groups constrained to coexist within a protein structure (see immediately below and Chapter 5, section 5.1.7.4). This represents the principal statement of the Mechanistic Assertion. 

Figure 1.7. Shown are the first reported data of the conversion by an elastic-contractile model protein of chemical energy due to an increase in concentration of acid into the mechanical work of contraction. A Length changes at constant force (isotonic contraction) in phosphate-buffered saline. B Force changes at constant length (isometric contraction) in phosphate-buffered saline. (Reproduced from Urry et al. )...

Figure 2.4. The lefthand side shows a representative sheet of y-irradiation cross-linked elastic-contractile model protein, designed for the conversion of an input energy into the output of pumping iron, per-...

Figure 2.6. In general, the conversion from the extended state to the contracted state shown in Figure 2.5 is graphed here as a systematic family of sigmoid-shaped curves with a common dependence of oil-like character of the elastic-contractile model protein whether the energy input is thermal, chemi-...

The sigmoid-shaped curves of Figure 2.6A represent the shortening of contraction that occurs on raising the temperature through the relevant temperature interval for the particular extent of oil-like character of the model protein. Elastic-contractile model proteins of more oillike composition contract at lower temperatures and over narrower temperature intervals. 

In general, the key chemicals for changing the folding temperature in our elastic-contractile model proteins are prevalent triggers of function in biology. 

Synthetic Elastic-contractile Model Protein Machines to Energize Phosphates... 

Ec(uivalence of Energy Conversion to Biology s Proteins yet Structural Limitations of Elastic-contractile Model Proteins... 

Much fundamental science came from the study of elastic-contractile model proteins. The elastic-contractile model proteins provided the molecular system for realizing the correct description of elasticity. Furthermore, competition for hydration between oil-like and polar. 

Figure 2.18. Energies are shown that can be inter-converted by means of elastic-contractile model proteins capable of exhibiting inverse temperature transitions functioning by means of the competition for hydration between oil-like and charged groups called an apolar-polar repulsive free energy of hydration. See Chapter 5 for a more complete development of the phenomenology and physical basis and Chapter 8 for details of the molecular process.

Figure 2.19. Example of the production of the elastic-contractile model protein, (G VG VP)i2i, by genetic engineering of E. coli. A Transformed E. coli shows large inclusion bodies of product having phase...

Figure 2.20. Elastic-contractile model proteins are used as temporciry functional scaffolding for soft tissue restoration by means of an attached normal cell capable of mechanochemical transduction to restore a natural tissue. A Elastic matrices without cell attachment sequences show no attachment of human fibroblasts. B Elastic matrix with cell attach-...

Figure 2.21. The designed elastic-contractile model proteins function by means of the apolar-polar repulsive free energy of hydration to achieve zero order release with simultaneous dispersal of delivery...

D-amino acid residue on the right (an optical isomer that does occur in biology, but in those peptides not encoded for by the genetic code). C The effect of insertion of a D-amino acid residue in an otherwise L-amino acid residue protein in the P-spiral structure of the elastic-contractile model protein of our focus would be to disrupt the regular structure. This is difficult to avoid completely in chemical synthesis, and it increases the temperature at which occurs the inverse temperature transition and decreases the heat of the transition due to less optimal association of oil-like groupings. 

Chemical Synthesis of Elastic-contractile Model Proteins... 

The family of dynamic elastic-contractile model proteins that form the basis for the assertions of the central message of this volume do not lend themselves to the precise spatial descriptions of proteins that form crystals. Nonetheless, important structural description is possible for the poly(GVGVP) family. Indeed, the experimental and computational elucidation of... 

Figure 3.12. Molecular structure of the parent elastic-contractile model protein as described in the text. See Chapter 5 for discussion of experimental basis of the structure. (Parts A, B, C, D, E, and F reproduced with permission from Urry et al., ° Cook et al., Urry, Urry, and Urry et al., respectively.)...

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