Evidence for cooperative effects in the binding of polyvalent metal ions to pure phosphatidylcholine bilayer vesicle surfaces

Adela Chrzeszczyk, Arnold Wishnia, Charles Jr Springer

Research output: Contribution to journalArticle

44 Citations (Scopus)

Abstract

An internal NMR monitor for the study of lanthanide ion (Ln3+) binding to phospholipid bilayer membranes has been developed. The dimethylphosphate anion, DMP-, forms labile complexes with Ln3+ in aqueous solution and in solutions also containing bilayer dispersions. The hyperfine shift in the DMP- resonance induced by Pr3+ ions has been used to determine the overall thermodynamic formation constants for the Pr(DMP)2+ and Pr(DMP)2 + complexes: 81 (M-1) and 349 (M-2) at 52°C; the limiting hyperfine shift (31P) at 52°C is 91.5 ppm downfield. These parameters, applied to the observed DMP- hyperfine shift in the presence of the membrane, establish both the free Pr3+ concentration and the amount of Pr3+ bound to the phospholipid surface. Extensive data for the binding of Pr3+ to the outer surfaces of sonicated vesicles yield a limiting hyperfine shift per Pr3+ of 181.6 ppm downfield for the dipalmitoylphosphatidylcholine 31P resonance at 52°C, clearly demonstrating that the binding stoichiometry is two DPPCs per Pr3+. A Hill analysis indicates that the binding data are more anti-cooperative than a realistic Langmuir isotherm, yet more cooperative than a Stern isotherm incorporating electrostatic considerations at the Debye-Hückel level. Fittings to specific models lead to a cooperative model in which tense (T) sites, with low affinity for Pr3+, present in the absence of metal ions, quickly give way to relaxed (R) sites (two DPPCs per site), with much higher affinity for Pr3+, as the amount of Pr3+ bound to the surface increases. The intrinsic equilibrium constants for the binding of Pr3+ to DPPC vesicles are 2 M-1 and 3 000 M-1 for the T and R sites, respectively, at 52°C. The distribution coefficient between these sites ([R]/[T]) in the absence of Ln3+ is 0.14 at 52°C. We picture the binding site conversion as a head-group conformational change involving mostly the choline moiety. Sketchy results for binding on the inside vesicle surface indicate that the overall affinity for Pr3+ is significantly greater and suggest that the site stoichiometry may be different.

Original languageEnglish (US)
Pages (from-to)28-48
Number of pages21
JournalBBA - Biomembranes
Volume648
Issue number1
DOIs
StatePublished - Oct 20 1981
Externally publishedYes

Fingerprint

Phosphatidylcholines
Metal ions
Metals
Ions
Phospholipids
Stoichiometry
Isotherms
1,2-Dipalmitoylphosphatidylcholine
Lanthanoid Series Elements
Membranes
Choline
Static Electricity
Thermodynamics
Anions
Equilibrium constants
Dispersions
Binding Sites
Electrostatics
Nuclear magnetic resonance

Keywords

  • Cooperative binding
  • NMR
  • Phosphatidylcholine
  • Phospholipid bilayer
  • Polyvalent metal ion

ASJC Scopus subject areas

  • Biochemistry
  • Biophysics
  • Cell Biology
  • Medicine(all)

Cite this

Evidence for cooperative effects in the binding of polyvalent metal ions to pure phosphatidylcholine bilayer vesicle surfaces. / Chrzeszczyk, Adela; Wishnia, Arnold; Springer, Charles Jr.

In: BBA - Biomembranes, Vol. 648, No. 1, 20.10.1981, p. 28-48.

Research output: Contribution to journalArticle

@article{07ae406a44044bee951e01cde56a7c54,
title = "Evidence for cooperative effects in the binding of polyvalent metal ions to pure phosphatidylcholine bilayer vesicle surfaces",
abstract = "An internal NMR monitor for the study of lanthanide ion (Ln3+) binding to phospholipid bilayer membranes has been developed. The dimethylphosphate anion, DMP-, forms labile complexes with Ln3+ in aqueous solution and in solutions also containing bilayer dispersions. The hyperfine shift in the DMP- resonance induced by Pr3+ ions has been used to determine the overall thermodynamic formation constants for the Pr(DMP)2+ and Pr(DMP)2 + complexes: 81 (M-1) and 349 (M-2) at 52°C; the limiting hyperfine shift (31P) at 52°C is 91.5 ppm downfield. These parameters, applied to the observed DMP- hyperfine shift in the presence of the membrane, establish both the free Pr3+ concentration and the amount of Pr3+ bound to the phospholipid surface. Extensive data for the binding of Pr3+ to the outer surfaces of sonicated vesicles yield a limiting hyperfine shift per Pr3+ of 181.6 ppm downfield for the dipalmitoylphosphatidylcholine 31P resonance at 52°C, clearly demonstrating that the binding stoichiometry is two DPPCs per Pr3+. A Hill analysis indicates that the binding data are more anti-cooperative than a realistic Langmuir isotherm, yet more cooperative than a Stern isotherm incorporating electrostatic considerations at the Debye-H{\"u}ckel level. Fittings to specific models lead to a cooperative model in which tense (T) sites, with low affinity for Pr3+, present in the absence of metal ions, quickly give way to relaxed (R) sites (two DPPCs per site), with much higher affinity for Pr3+, as the amount of Pr3+ bound to the surface increases. The intrinsic equilibrium constants for the binding of Pr3+ to DPPC vesicles are 2 M-1 and 3 000 M-1 for the T and R sites, respectively, at 52°C. The distribution coefficient between these sites ([R]/[T]) in the absence of Ln3+ is 0.14 at 52°C. We picture the binding site conversion as a head-group conformational change involving mostly the choline moiety. Sketchy results for binding on the inside vesicle surface indicate that the overall affinity for Pr3+ is significantly greater and suggest that the site stoichiometry may be different.",
keywords = "Cooperative binding, NMR, Phosphatidylcholine, Phospholipid bilayer, Polyvalent metal ion",
author = "Adela Chrzeszczyk and Arnold Wishnia and Springer, {Charles Jr}",
year = "1981",
month = "10",
day = "20",
doi = "10.1016/0005-2736(81)90121-8",
language = "English (US)",
volume = "648",
pages = "28--48",
journal = "Biochimica et Biophysica Acta - Biomembranes",
issn = "0005-2736",
publisher = "Elsevier",
number = "1",

}

TY - JOUR

T1 - Evidence for cooperative effects in the binding of polyvalent metal ions to pure phosphatidylcholine bilayer vesicle surfaces

AU - Chrzeszczyk, Adela

AU - Wishnia, Arnold

AU - Springer, Charles Jr

PY - 1981/10/20

Y1 - 1981/10/20

N2 - An internal NMR monitor for the study of lanthanide ion (Ln3+) binding to phospholipid bilayer membranes has been developed. The dimethylphosphate anion, DMP-, forms labile complexes with Ln3+ in aqueous solution and in solutions also containing bilayer dispersions. The hyperfine shift in the DMP- resonance induced by Pr3+ ions has been used to determine the overall thermodynamic formation constants for the Pr(DMP)2+ and Pr(DMP)2 + complexes: 81 (M-1) and 349 (M-2) at 52°C; the limiting hyperfine shift (31P) at 52°C is 91.5 ppm downfield. These parameters, applied to the observed DMP- hyperfine shift in the presence of the membrane, establish both the free Pr3+ concentration and the amount of Pr3+ bound to the phospholipid surface. Extensive data for the binding of Pr3+ to the outer surfaces of sonicated vesicles yield a limiting hyperfine shift per Pr3+ of 181.6 ppm downfield for the dipalmitoylphosphatidylcholine 31P resonance at 52°C, clearly demonstrating that the binding stoichiometry is two DPPCs per Pr3+. A Hill analysis indicates that the binding data are more anti-cooperative than a realistic Langmuir isotherm, yet more cooperative than a Stern isotherm incorporating electrostatic considerations at the Debye-Hückel level. Fittings to specific models lead to a cooperative model in which tense (T) sites, with low affinity for Pr3+, present in the absence of metal ions, quickly give way to relaxed (R) sites (two DPPCs per site), with much higher affinity for Pr3+, as the amount of Pr3+ bound to the surface increases. The intrinsic equilibrium constants for the binding of Pr3+ to DPPC vesicles are 2 M-1 and 3 000 M-1 for the T and R sites, respectively, at 52°C. The distribution coefficient between these sites ([R]/[T]) in the absence of Ln3+ is 0.14 at 52°C. We picture the binding site conversion as a head-group conformational change involving mostly the choline moiety. Sketchy results for binding on the inside vesicle surface indicate that the overall affinity for Pr3+ is significantly greater and suggest that the site stoichiometry may be different.

AB - An internal NMR monitor for the study of lanthanide ion (Ln3+) binding to phospholipid bilayer membranes has been developed. The dimethylphosphate anion, DMP-, forms labile complexes with Ln3+ in aqueous solution and in solutions also containing bilayer dispersions. The hyperfine shift in the DMP- resonance induced by Pr3+ ions has been used to determine the overall thermodynamic formation constants for the Pr(DMP)2+ and Pr(DMP)2 + complexes: 81 (M-1) and 349 (M-2) at 52°C; the limiting hyperfine shift (31P) at 52°C is 91.5 ppm downfield. These parameters, applied to the observed DMP- hyperfine shift in the presence of the membrane, establish both the free Pr3+ concentration and the amount of Pr3+ bound to the phospholipid surface. Extensive data for the binding of Pr3+ to the outer surfaces of sonicated vesicles yield a limiting hyperfine shift per Pr3+ of 181.6 ppm downfield for the dipalmitoylphosphatidylcholine 31P resonance at 52°C, clearly demonstrating that the binding stoichiometry is two DPPCs per Pr3+. A Hill analysis indicates that the binding data are more anti-cooperative than a realistic Langmuir isotherm, yet more cooperative than a Stern isotherm incorporating electrostatic considerations at the Debye-Hückel level. Fittings to specific models lead to a cooperative model in which tense (T) sites, with low affinity for Pr3+, present in the absence of metal ions, quickly give way to relaxed (R) sites (two DPPCs per site), with much higher affinity for Pr3+, as the amount of Pr3+ bound to the surface increases. The intrinsic equilibrium constants for the binding of Pr3+ to DPPC vesicles are 2 M-1 and 3 000 M-1 for the T and R sites, respectively, at 52°C. The distribution coefficient between these sites ([R]/[T]) in the absence of Ln3+ is 0.14 at 52°C. We picture the binding site conversion as a head-group conformational change involving mostly the choline moiety. Sketchy results for binding on the inside vesicle surface indicate that the overall affinity for Pr3+ is significantly greater and suggest that the site stoichiometry may be different.

KW - Cooperative binding

KW - NMR

KW - Phosphatidylcholine

KW - Phospholipid bilayer

KW - Polyvalent metal ion

UR - http://www.scopus.com/inward/record.url?scp=0019885395&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0019885395&partnerID=8YFLogxK

U2 - 10.1016/0005-2736(81)90121-8

DO - 10.1016/0005-2736(81)90121-8

M3 - Article

VL - 648

SP - 28

EP - 48

JO - Biochimica et Biophysica Acta - Biomembranes

JF - Biochimica et Biophysica Acta - Biomembranes

SN - 0005-2736

IS - 1

ER -