X-Message-Number: 12275
Date: Tue, 17 Aug 1999 23:18:34 -0700 (PDT)
From: Doug Skrecky <>
Subject: chemical fixation may be reversible

  Baschong W.  Baschong-Prescianotto C.  Kellenberger E.
  Reversible fixation for the study of
  morphology and macromolecular composition of fragile biological structures.
  European Journal of Cell Biology.  32(1):1-6, 1983 Nov.
  Many subcellular structures are assemblies of subunits, which are in dynamic
  equilibrium with free subunits in solution. Their dissociation upon dilution,
  resulting from cell lysis, can be prevented by adequate
  fixation. If the latter is reversible, the
  constituting proteins of such subcellular structures can be analysed
  electrophoretically. Polyheads of bacteriophage T4 are in dynamic equilibrium
  with their subunits. They fit very well as a probe to measure the efficiency
  of crosslinking by the arrest of dissociation upon dilution and upon
  treatment with hot SDS. Formaldehyde (5%, 20 min, 20 degrees C) leads to a
  stabilisation comparable to fixation with glutaraldehyde
  (1%, 30 min). The fixation is shown to be
  reversible up to 86% by acid and borohydride treatment, but
  is stable towards heat and SDS-mercaptoethanol. Bands of the reversed
  proteins are neat and not found in detectably different positions in
  comparison to controls, when checked by SDS gel electrophoresis.

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