Conformational Equilibria of Multimodal Chromatography Ligands in Water and Bound to Protein Surfaces

Camille L. Bilodeau, Edmond Y Lau, Steven M. Cramer, Shekhar Garde

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

Multimodal chromatography uses small ligands with multiple modes of interaction, e.g., charged, hydrophobic or hydrogen bonding, to separate proteins from complex mixtures. The mechanism by which multimodal ligands interact with proteins is expected to be affected by ligand conformations, among other factors. Here, we study conformational equilibria of two commercially used multimodal cation exchange ligands, Capto MMC and Nuvia cPrime, in a range of solvents, a Lennard-Jones (LJ) liquid, ethanol, and water, using molecular dynamics (MD) simulations. By mapping ligand conformations onto two key torsion angles, ω and φ, in these solvents and in low and high dielectric media, we quantify the relative importance of intramolecular and solvent-mediated interactions. In a high dielectric medium, Capto MMC preferentially samples three conformations, which are stabilized by a combination of an intramolecular torsion potential (on ω) and LJ interactions. In an LJ liquid, solvent molecules compete with intramolecular interactions while simultaneously providing an osmotic force, stabilizing both closer and farther distances between ligand sites. This has the overall effect of "flattening out" the conformational landscape. Interestingly, in ethanol and water, hydrogen bonding between the amide hydrogen and solvent molecules stabilizes two additional conformations of Capto MMC in which ω takes on less favorable cis-like configurations. MD simulations of ligands in free solution with three therapeutic antibody fragments show that ligand conformational equilibria remain effectively unchanged upon binding to proteins. Although, there is 20-30% dehydration of the overall ligand upon binding, the hydrogen-bonding sites are dehydrated to a much smaller extent, particularly in cis-like configurations. Conformational preferences of Nuvia cPrime are similar to that of Capto MMC, except for the effect of symmetry arising from the absence of an alkyl thiol tail. Characterizing the conformational equilibria of these two ligands in free solution and bound to a protein provides a foundation for developing a mechanistic understanding of protein-multimodal ligand interactions.

Original languageEnglish (US)
Pages (from-to)4833-4843
Number of pages11
JournalJournal of Physical Chemistry B
Volume123
Issue number23
DOIs
StatePublished - Jun 13 2019
Externally publishedYes

Fingerprint

chromatography
Chromatography
Membrane Proteins
Ligands
proteins
Proteins
ligands
Water
water
Conformations
Hydrogen Bonding
Hydrogen bonds
hydrogen
Molecular Dynamics Simulation
Torsional stress
interactions
torsion
Molecular dynamics
Ethanol
ethyl alcohol

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry

Cite this

Conformational Equilibria of Multimodal Chromatography Ligands in Water and Bound to Protein Surfaces. / Bilodeau, Camille L.; Lau, Edmond Y; Cramer, Steven M.; Garde, Shekhar.

In: Journal of Physical Chemistry B, Vol. 123, No. 23, 13.06.2019, p. 4833-4843.

Research output: Contribution to journalArticle

Bilodeau, Camille L. ; Lau, Edmond Y ; Cramer, Steven M. ; Garde, Shekhar. / Conformational Equilibria of Multimodal Chromatography Ligands in Water and Bound to Protein Surfaces. In: Journal of Physical Chemistry B. 2019 ; Vol. 123, No. 23. pp. 4833-4843.
@article{69a619b67aa647be825c093ddf899089,
title = "Conformational Equilibria of Multimodal Chromatography Ligands in Water and Bound to Protein Surfaces",
abstract = "Multimodal chromatography uses small ligands with multiple modes of interaction, e.g., charged, hydrophobic or hydrogen bonding, to separate proteins from complex mixtures. The mechanism by which multimodal ligands interact with proteins is expected to be affected by ligand conformations, among other factors. Here, we study conformational equilibria of two commercially used multimodal cation exchange ligands, Capto MMC and Nuvia cPrime, in a range of solvents, a Lennard-Jones (LJ) liquid, ethanol, and water, using molecular dynamics (MD) simulations. By mapping ligand conformations onto two key torsion angles, ω and {\"I}†, in these solvents and in low and high dielectric media, we quantify the relative importance of intramolecular and solvent-mediated interactions. In a high dielectric medium, Capto MMC preferentially samples three conformations, which are stabilized by a combination of an intramolecular torsion potential (on ω) and LJ interactions. In an LJ liquid, solvent molecules compete with intramolecular interactions while simultaneously providing an osmotic force, stabilizing both closer and farther distances between ligand sites. This has the overall effect of {"}flattening out{"} the conformational landscape. Interestingly, in ethanol and water, hydrogen bonding between the amide hydrogen and solvent molecules stabilizes two additional conformations of Capto MMC in which ω takes on less favorable cis-like configurations. MD simulations of ligands in free solution with three therapeutic antibody fragments show that ligand conformational equilibria remain effectively unchanged upon binding to proteins. Although, there is 20-30{\%} dehydration of the overall ligand upon binding, the hydrogen-bonding sites are dehydrated to a much smaller extent, particularly in cis-like configurations. Conformational preferences of Nuvia cPrime are similar to that of Capto MMC, except for the effect of symmetry arising from the absence of an alkyl thiol tail. Characterizing the conformational equilibria of these two ligands in free solution and bound to a protein provides a foundation for developing a mechanistic understanding of protein-multimodal ligand interactions.",
author = "Bilodeau, {Camille L.} and Lau, {Edmond Y} and Cramer, {Steven M.} and Shekhar Garde",
year = "2019",
month = "6",
day = "13",
doi = "10.1021/acs.jpcb.9b01218",
language = "English (US)",
volume = "123",
pages = "4833--4843",
journal = "Journal of Physical Chemistry B Materials",
issn = "1520-6106",
publisher = "American Chemical Society",
number = "23",

}

TY - JOUR

T1 - Conformational Equilibria of Multimodal Chromatography Ligands in Water and Bound to Protein Surfaces

AU - Bilodeau, Camille L.

AU - Lau, Edmond Y

AU - Cramer, Steven M.

AU - Garde, Shekhar

PY - 2019/6/13

Y1 - 2019/6/13

N2 - Multimodal chromatography uses small ligands with multiple modes of interaction, e.g., charged, hydrophobic or hydrogen bonding, to separate proteins from complex mixtures. The mechanism by which multimodal ligands interact with proteins is expected to be affected by ligand conformations, among other factors. Here, we study conformational equilibria of two commercially used multimodal cation exchange ligands, Capto MMC and Nuvia cPrime, in a range of solvents, a Lennard-Jones (LJ) liquid, ethanol, and water, using molecular dynamics (MD) simulations. By mapping ligand conformations onto two key torsion angles, ω and φ, in these solvents and in low and high dielectric media, we quantify the relative importance of intramolecular and solvent-mediated interactions. In a high dielectric medium, Capto MMC preferentially samples three conformations, which are stabilized by a combination of an intramolecular torsion potential (on ω) and LJ interactions. In an LJ liquid, solvent molecules compete with intramolecular interactions while simultaneously providing an osmotic force, stabilizing both closer and farther distances between ligand sites. This has the overall effect of "flattening out" the conformational landscape. Interestingly, in ethanol and water, hydrogen bonding between the amide hydrogen and solvent molecules stabilizes two additional conformations of Capto MMC in which ω takes on less favorable cis-like configurations. MD simulations of ligands in free solution with three therapeutic antibody fragments show that ligand conformational equilibria remain effectively unchanged upon binding to proteins. Although, there is 20-30% dehydration of the overall ligand upon binding, the hydrogen-bonding sites are dehydrated to a much smaller extent, particularly in cis-like configurations. Conformational preferences of Nuvia cPrime are similar to that of Capto MMC, except for the effect of symmetry arising from the absence of an alkyl thiol tail. Characterizing the conformational equilibria of these two ligands in free solution and bound to a protein provides a foundation for developing a mechanistic understanding of protein-multimodal ligand interactions.

AB - Multimodal chromatography uses small ligands with multiple modes of interaction, e.g., charged, hydrophobic or hydrogen bonding, to separate proteins from complex mixtures. The mechanism by which multimodal ligands interact with proteins is expected to be affected by ligand conformations, among other factors. Here, we study conformational equilibria of two commercially used multimodal cation exchange ligands, Capto MMC and Nuvia cPrime, in a range of solvents, a Lennard-Jones (LJ) liquid, ethanol, and water, using molecular dynamics (MD) simulations. By mapping ligand conformations onto two key torsion angles, ω and φ, in these solvents and in low and high dielectric media, we quantify the relative importance of intramolecular and solvent-mediated interactions. In a high dielectric medium, Capto MMC preferentially samples three conformations, which are stabilized by a combination of an intramolecular torsion potential (on ω) and LJ interactions. In an LJ liquid, solvent molecules compete with intramolecular interactions while simultaneously providing an osmotic force, stabilizing both closer and farther distances between ligand sites. This has the overall effect of "flattening out" the conformational landscape. Interestingly, in ethanol and water, hydrogen bonding between the amide hydrogen and solvent molecules stabilizes two additional conformations of Capto MMC in which ω takes on less favorable cis-like configurations. MD simulations of ligands in free solution with three therapeutic antibody fragments show that ligand conformational equilibria remain effectively unchanged upon binding to proteins. Although, there is 20-30% dehydration of the overall ligand upon binding, the hydrogen-bonding sites are dehydrated to a much smaller extent, particularly in cis-like configurations. Conformational preferences of Nuvia cPrime are similar to that of Capto MMC, except for the effect of symmetry arising from the absence of an alkyl thiol tail. Characterizing the conformational equilibria of these two ligands in free solution and bound to a protein provides a foundation for developing a mechanistic understanding of protein-multimodal ligand interactions.

UR - http://www.scopus.com/inward/record.url?scp=85066971961&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=85066971961&partnerID=8YFLogxK

U2 - 10.1021/acs.jpcb.9b01218

DO - 10.1021/acs.jpcb.9b01218

M3 - Article

C2 - 31117605

AN - SCOPUS:85066971961

VL - 123

SP - 4833

EP - 4843

JO - Journal of Physical Chemistry B Materials

JF - Journal of Physical Chemistry B Materials

SN - 1520-6106

IS - 23

ER -