Electrochemical Transduction in Elastic Protein-Based Polymers: A Model for an Energy Conversion Step of Oxidative Phosphorylation

Urry, Dan W.; Hayes, Larry; Gowda, D. Channe; Peng, Shao Qing; Ning, Jianguo

doi:10.1006/bbrc.1995.1760

Cited by 19 publications

(12 citation statements)

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“…5). This indicates that positively charged, unmodified lysine residues are not major determinants of the temperature of transition of tropoelastin, probably because they are outside the directly associating hydrophobic regions (23). In contrast, chemical modification of the amino groups on lysine side chains showed a substantial effect on the influence of GAGs on coacervation.…”

Section: Glycosaminoglycan Interactions Are Mainly Mediated Through Lmentioning

confidence: 93%

Glycosaminoglycans Mediate the Coacervation of Human Tropoelastin through Dominant Charge Interactions Involving Lysine Side Chains

Wu¹,

Vrhovski²,

Weiss

1999

Journal of Biological Chemistry

132

137

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Following cellular secretion into the extracellular matrix, tropoelastin is transported, deposited, and crosslinked to make elastin. Assembly by coacervation was examined for an isoform of tropoelastin that lacks the hydrophilic domain encoded by exon 26A. It is equivalent to a naturally secreted form of tropoelastin and shows similar coacervation performance to its partner containing 26A, thereby generalizing the concept that splice form variants are able to coacervate under comparable conditions. This is optimal under physiological conditions of temperature, salt concentration, and pH. The proteins were examined for their ability to interact with extracellular matrix glycosaminoglycans. These negatively charged molecules interacted with positively charged lysine residues and promoted coacervation of tropoelastin in a temperature-and concentrationdependent manner. A testable model for elastin-glycosaminoglycan interactions is proposed, where tropoelastin deposition during elastogenesis is encouraged by local exposure to matrix glycosaminoglycans. Unmodified proteins are retained at ϳ3 M dissociation constant. Following lysyl oxidase modification of tropoelastin lysine residues, they are released from glycosaminoglycan interactions, thereby permitting those residues to contribute to elastin cross-links.

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Section: Glycosaminoglycan Interactions Are Mainly Mediated Through Lmentioning

confidence: 93%

Glycosaminoglycans Mediate the Coacervation of Human Tropoelastin through Dominant Charge Interactions Involving Lysine Side Chains

Wu¹,

Vrhovski²,

Weiss

1999

Journal of Biological Chemistry

132

137

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“…A specific example involving the carboxyl of an aspartic acid residue and an N -methyl nicotinamide attached to a Lys side chain is seen in Figure B. Reduction of the nicotinamide lowers T t and raises the p K a of the carboxyl. , As the reaction is carried out at pH 9.2 for reasons of N -methyl nicotinamide stability and as the p K a shifts from 8.5 to 11, at this pH reduction drives the uptake of a proton. The electrical energy input has resulted in a chemical energy output.…”

Section: The T T-perspective: a Point Of View Of Greatest Simplicity ...mentioning

confidence: 99%

“…Not only can organization be the product of different energy inputs but a change in organization, i.e., a change in molecular folding and assembly, can be the catalyst for interconverting pairs of energies not including mechanical energy. Should the model protein contain two different functional entities, each responsive to the change in a different intensive variable, then a change in one intensive variable represents an energy input that by altering one functional group acts upon and changes the property of the second functional group as the mechanism for achieving an energy output. − …”

Section: Introductionmentioning

confidence: 99%

“…By way of an example that is to be described in more detail later in this article, consider a model protein designed to contain both a carboxylate function and an oxidized state of a redox function. With appropriate design of the protein-based polymer, electrochemical reduction of the redox function, by driving a change in molecular organization, effects a change in the p K a of the carboxyl and causes the uptake of a proton. , The application of a reductive electrochemical potential has resulted in a change in the chemical potential of proton in the system. This is the conversion of an electrical energy input into a chemical energy output, as occurs in the electron transport system of the inner mitochondrial and thylakoid membranes.…”

Section: Introductionmentioning

confidence: 99%

“…The next step in developing a general formalism for biological free energy transduction is to replace the degree of protonation of carboxylates with the degree of reduction of an attached redox couple and to plot the degree of reduction vs the electromotive force or the applied electrical potential, suitably referenced. Completing the correlation, as with protonation, the reduction of a redox couple can also be used to perform the mechanical work of lifting a weight or even to perform the chemical work of shifting a p K a with the pickup of protons . Therefore, the general formalism for free energy transduction can be given in terms of fraction of energy output as a function of energy input.…”

Section: Introductionmentioning

confidence: 99%

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Physical Chemistry of Biological Free Energy Transduction As Demonstrated by Elastic Protein-Based Polymers

1997

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This article, on protein-based polymers comprised of repeating peptide sequences, reviews studies from the author's laboratory covering a period of more than two decades; it presents a general mechanism for protein folding and function and demonstrates the mechanism by designing model proteins capable of performing many of the energy conversions that sustain life and by designing diverse biomolecular machines and materials with promising applications for society. All polymers with the correct balance of apolar and polar moieties, including water soluble proteins and protein-based polymers, increase order by a hydrophobic folding and assembly transition as the temperature is raised above a critical onset temperature, designated as T t. Instead of varying the temperature, however, innumerable variables lower the value of T t from above to below the operating temperature to drive folding and function. Thus, this inverse temperature transition provides a fundamental mechanism whereby proteins fold and function and whereby the energy conversions that sustain living organisms can occur at constant temperature. Phenomenologically, this mechanism results in five axioms or principles for protein function and protein engineering whereby designed protein-based polymers interconvert six free energies interconverted by living organisms. The six intensive variables for biological free energy transduction are mechanical force, temperature, chemical potential, electrochemical potential, pressure, and electromagnetic radiation. No matter how seemingly disparate, virtually every protein function can be classified in terms of a form, or forms, of free energy transduction. Mechanistically, the design, preparation, and characterization of families of related protein-based polymers show the usually considered electrostatic charge−charge interactions not to be the physical basis for the energy conversions. Instead, presented and analyzed experimental data indicate competition for hydration between apolar and polar species to be responsible. In short, the value of T t is determined by the amount of water of hydrophobic hydration; hydration of polar species, as required on ionization, occurs at the expense of hydrophobic hydration and raises the value of T t, and the energy required to destructure hydrophobic hydration results in hydrophobic-induced pK a shifts. Formalisms are outlined that describe hydrophobic-induced pK a shifts, related positive cooperativity of acid-based titration curves, and the involved energy conversions.

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Five axioms for the functional design of peptide-based polymers as molecular machines and materials: Principle for macromolecular assemblies

Urry

1998

Biopolymers

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Peptide‐based polymers can be transformable hydrogels, elastomers, regular thermoplastics, or inverse thermoplastics, and can function as diverse molecular machines. When of the appropriate composition, these polymers exhibit hydrophobic folding and assembly transitions in the accessible aqueous range as the temperature is raised from below to above a critical value referred to as Tt, the temperature for the onset of an inverse temperature transition. In this article, the design of these Tt‐type molecular machines and materials is systematized in terms of five axioms for peptide‐based polymer engineering: The first axiom is represented by a hydrophobicity scale that provides the information with which to design peptide‐based polymers with a particular value of Tt. The second axiom concerns thermomechanical transduction wherein raising the temperature from below to above Tt results in hydrophobic folding and assembly with the performance of mechanical work. The third axiom states that at constant temperature, diverse energy inputs lower Tt from above to below an operating temperature by acting on a functional moiety within the polymer to drive hydrophobic folding and assembly with the isothermal performance of mechanical work. The fourth axiom concerns polymer compositions having two different functional groups, with each responsive to a different energy input and with each part of a common hydrophobic folding domain. The two functional groups become coupled one to the other such that an energy input acting on one functional group becomes an energy output by having changed the property of the second functional group. The fifth axiom states that the efficiency of conversion from one form of energy to another by means of the fourth axiom increases nonlinearly with hydrophobicity of the common hydrophobic folding and assembly domain. These phenomenological axioms allow design of peptide‐based polymers capable of diverse energy conversions involving the intensive variables of mechanical force, temperature, pressure, chemical potential, electrochemical potential, and light. Knowledge of the physical process underlying the five axioms enhances their use in the design of materials and devices for medical and nonmedical applications. The physical process is demonstrated by the use of cartoons. © 1998 John Wiley & Sons, Inc. Biopoly 47: 167–178, 1998

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Electrochemical Transduction in Elastic Protein-Based Polymers: A Model for an Energy Conversion Step of Oxidative Phosphorylation

Cited by 19 publications

References 0 publications

Glycosaminoglycans Mediate the Coacervation of Human Tropoelastin through Dominant Charge Interactions Involving Lysine Side Chains

Glycosaminoglycans Mediate the Coacervation of Human Tropoelastin through Dominant Charge Interactions Involving Lysine Side Chains

Physical Chemistry of Biological Free Energy Transduction As Demonstrated by Elastic Protein-Based Polymers

Five axioms for the functional design of peptide-based polymers as molecular machines and materials: Principle for macromolecular assemblies

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