Related Experiment Video
Updated: Sep 24, 2026

Optimization of Synthetic Proteins: Identification of Interpositional Dependencies Indicating Structurally and/or Functionally Linked Residues
Published on: July 14, 2015
Single-residue substitution in homopolypeptides: perturbative helix-coil theory at a single site
1Institute of Molecular Biology, University of Oregon, Eugene 97403.
Abstract:
Based on Lifson-Roig's helix-coil transition theory, substitution of a single heteroresidue into a homopolymer host is studied. This study models recent experiments that substitute a single amino acid into a small peptide in water [A. Chakrabartty, J. A. Schellman, and R. L. Baldwin (1991), Nature, Vol. 351, pp. 586-688]. Our formalism, which is based on a perturbation method, differs from the existing theory for sequenced polymers and is naturally analogous, hence likely to be useful, to substitution experiments in the laboratory. It is shown that the intrinsic helix propensity w is directly proportional to the equilibrium constant for the helix-coil equilibrium of a single residue in a host peptide. This intuitive new result will simplify experimental data interpretations for measurements of the helical conformation on the single amino acid level. It is also shown that substitution affects the total helicity of the host peptide according to two considerations: the helicity of the replaced residue prior to the substitution, and the sensitivity of the site, a measure of neighboring interactions. The relationship between substitution stability and thermal stability is explored.
More Related Videos
10:31Residue-Specific Exchange of Proline by Proline Analogs in Fluorescent Proteins: How "Molecular Surgery" of the Backbone Affects Folding and Stability
Published on: February 3, 2022
06:50Computational Prediction of Amino Acid Preferences of Potentially Multispecific Peptide-Binding Domains Involved in Protein-Protein Interactions
Published on: January 26, 2024
Related Concept Videos
Mutations
Conserved Binding Sites
Binding sites are often located in large pockets, and if their location on a protein’s surface is unknown, it can be predicted using various approaches. The energetic method computationally analyses the...
Ligand Binding and Linkage
Cooperative Allosteric Transitions
Allosteric Proteins-ATCase
Aspartate transcarbamoylase (ATCase) is a cytosolic enzyme that catalyzes the condensation of L-aspartate and carbamoyl phosphate to N-carbamoyl-L-aspartate. This reaction is the first step in pyrimidine biosynthesis. UTP and CTP, the end products of the pyrimidine synthesis pathway,...
¹H NMR Chemical Shift Equivalence: Homotopic and Heterotopic Protons