X-Message-Number: 11591
Date: Wed, 21 Apr 1999 10:21:38 -0700 (PDT)
From: Doug Skrecky <>
Subject: membrane permeability of polyols

Authors
  Kiyosawa K.
Institution
  Department of Biophysical Engineering, Faculty of Engineering Science, Osaka
  University, Japan.
Title
  Volumetric properties of
  polyols (ethylene glycol, glycerol, meso-erythritol, xylitol
  and mannitol) in relation to their membrane permeability: group additivity
  and estimation of the maximum radius of their molecules.
Source
  Biochimica et Biophysica Acta.  1064(2):251-5, 1991 May 7.
Abstract
  The relationship of molecular volume and maximum molecular radii to the
  ability of some polyols, ethylene glycol, glycerol and
  meso-erythritol, to permeate the Chara cell membrane and to the inability of
  one of the polyols, mannitol, to permeate the Chara cell
  membrane, was examined by measuring the partial molar volumes of the
  polyols, Vm(2). Analysis of Vm(2) at infinite dilution
  showed that group additivity is maintained for all the groups, i.e., CH2OH
  and CHOH, of the polyols tested. However, as the
  permeability and impermeability could not be related to the geometrical
  properties of the polyol molecules based only on the
  thermodynamic quantities, molecular models of the polyol molecules were
  constructed using the CPK(Corey-Pauling Koltum) molecular model, which is
  designed to have the van der Waals radius of 1 A equivalent to 1.25 cm. The
  results showed that the maximum radius of the water-filled pore (hydrophilic
  channel) should be 3.2-3.3 A, and the longer the axial length and maximum
  radius of the polyol molecule, the lesser was its permeative ability. All the
  experimental and analytical results and inferences support the idea that
  water molecules pass across the cell membrane through a narrow pore in a
  single-file fashion.

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