Increased adhesion between neutral lipid bilayers: interbilayer bridges formed by tannic acid.

Published

Journal Article

Tannic acid (TA) is a naturally occurring polyphenolic compound that aggregates membranes and neutral phosolipid vesicles and precipitates many proteins. This study analyzes TA binding to lipid membranes and the ensuing aggregation. The optical density of dispersions of phosphatidylcholine (PC) vesicles increased upon the addition of TA and electron micrographs showed that TA caused the vesicles to aggregate and form stacks of tightly packed disks. Solution calorimetry showed that TA bound to PC bilayers with a molar binding enthalpy of -8.3 kcal/mol and zeta potential measurements revealed that TA imparted a small negative charge to PC vesicles. Monolayer studies showed that TA bound to PC with a dissociation constant of 1.5 microM and reduced the dipole potential by up to 250 mV. Both the increase in optical density and decrease in dipole potential produced by TA could be reversed by the addition of polyvinylpyrrolidone, a compound that chelates TA by providing H-bond acceptor groups. NMR, micropipette aspiration, and x-ray diffraction experiments showed that TA incorporated into liquid crystalline PC membranes, increasing the area per lipid molecule and decreasing the bilayer thickness by 2 to 4%. 2H-NMR quadrupole splitting measurements also showed that TA associated with a PC molecule for times much less than 10(-4) s. In gel phase bilayers, TA caused the hydrocarbon chains from apposing monolayers to fully interdigitate. X-ray diffraction measurements of both gel and liquid crystalline dispersions showed that TA, at a critical concentration of about 1 mM, reduced the fluid spacing between adjacent bilayers by 8-10 A. These data place severe constraints on how TA can pack between adjacent bilayers and cause vesicles to adhere. We conclude that TA promotes vesicle aggregation by reducing the fluid spacing between bilayers by the formation of transient interbilayer bridges by inserting its digallic acid residues into the interfacial regions of adjacent bilayers and spanning the interbilayer space.

Full Text

Duke Authors

Cited Authors

  • Simon, SA; Disalvo, EA; Gawrisch, K; Borovyagin, V; Toone, E; Schiffman, SS; Needham, D; McIntosh, TJ

Published Date

  • June 1, 1994

Published In

Volume / Issue

  • 66 / 6

Start / End Page

  • 1943 - 1958

PubMed ID

  • 8075329

Pubmed Central ID

  • 8075329

International Standard Serial Number (ISSN)

  • 0006-3495

Digital Object Identifier (DOI)

  • 10.1016/S0006-3495(94)80988-9

Language

  • eng

Conference Location

  • United States