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Tris buffer causes acyl chain interdigitation in phosphatidylglycerol.

Publication ,  Journal Article
Wilkinson, DA; Tirrell, DA; Turek, AB; McIntosh, TJ
Published in: Biochim Biophys Acta
December 11, 1987

The structure of the gel phase and the properties of the acyl chain disordering transition of dipalmitoyl phosphatidylglycerol (DPPG) have been studied using differential scanning calorimetry, differential scanning dilatometry, and X-ray diffraction. In the presence of small, monovalent cations, DPPG at 22 degrees C exists in a lamellar phase in which the hydrocarbon chains are tilted from the perpendicular to the bilayer surface. Around 34 degrees C, there is a small pretransition (delta H less than 1 kcal/mol) followed by the main transition at 40.4 degrees C (delta H = 8.3 kcal/mol; delta V = 0.0381 ml/g). If DPPG is suspended in Tris-HCl buffer in the absence of other monovalent cations, X-ray diffraction data show that at 22 degrees C, the gel phase consists of interdigitated acyl chains perpendicular to the plane of the bilayer. No pretransition is observed and the main transition occurs at 41.3 degrees C with delta H = 9.1 kcal/mol and delta V = 0.0514 ml/g. If sufficient Na+ or K+ ions are added to the Tris-buffered DPPG, the phase behavior reverts to what is observed in the absence of Tris. Analysis of the energetics of the main transition shows that the increase in van der Waals interaction energy resulting from the larger delta V in Tris can be compensated by the favorable energetics of removing terminal methyl groups from the bilayer surface. The amount of disordering, i.e. formation of gauche rotamers, is likely to be the same in Tris as it is in buffers without amphiphilic cations.

Duke Scholars

Published In

Biochim Biophys Acta

DOI

ISSN

0006-3002

Publication Date

December 11, 1987

Volume

905

Issue

2

Start / End Page

447 / 453

Location

Netherlands

Related Subject Headings

  • X-Ray Diffraction
  • Tromethamine
  • Phosphatidylglycerols
  • Molecular Conformation
  • Lipid Bilayers
  • Gels
  • Calorimetry, Differential Scanning
  • 51 Physical sciences
  • 31 Biological sciences
  • 06 Biological Sciences
 

Citation

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Wilkinson, D. A., Tirrell, D. A., Turek, A. B., & McIntosh, T. J. (1987). Tris buffer causes acyl chain interdigitation in phosphatidylglycerol. Biochim Biophys Acta, 905(2), 447–453. https://doi.org/10.1016/0005-2736(87)90474-3
Wilkinson, D. A., D. A. Tirrell, A. B. Turek, and T. J. McIntosh. “Tris buffer causes acyl chain interdigitation in phosphatidylglycerol.Biochim Biophys Acta 905, no. 2 (December 11, 1987): 447–53. https://doi.org/10.1016/0005-2736(87)90474-3.
Wilkinson DA, Tirrell DA, Turek AB, McIntosh TJ. Tris buffer causes acyl chain interdigitation in phosphatidylglycerol. Biochim Biophys Acta. 1987 Dec 11;905(2):447–53.
Wilkinson, D. A., et al. “Tris buffer causes acyl chain interdigitation in phosphatidylglycerol.Biochim Biophys Acta, vol. 905, no. 2, Dec. 1987, pp. 447–53. Pubmed, doi:10.1016/0005-2736(87)90474-3.
Wilkinson DA, Tirrell DA, Turek AB, McIntosh TJ. Tris buffer causes acyl chain interdigitation in phosphatidylglycerol. Biochim Biophys Acta. 1987 Dec 11;905(2):447–453.

Published In

Biochim Biophys Acta

DOI

ISSN

0006-3002

Publication Date

December 11, 1987

Volume

905

Issue

2

Start / End Page

447 / 453

Location

Netherlands

Related Subject Headings

  • X-Ray Diffraction
  • Tromethamine
  • Phosphatidylglycerols
  • Molecular Conformation
  • Lipid Bilayers
  • Gels
  • Calorimetry, Differential Scanning
  • 51 Physical sciences
  • 31 Biological sciences
  • 06 Biological Sciences