X-Message-Number: 11568
Date: Sat, 17 Apr 1999 09:32:13 -0700 (PDT)
From: Doug Skrecky <>
Subject: cysteine reduces cryoprotectant toxicity

Authors
  Karran G.  Legge M.
Institution
  Department of Biochemistry, University of Otago, Dunedin, New Zealand.
Title
  Non-enzymatic formation of
  formaldehyde in mouse oocyte freezing mixtures.
Source
  Human Reproduction.  11(12):2681-6, 1996 Dec.
Abstract
  Three cryoprotectant solvents, dimethylsulphoxide, 1,2-propanediol and
  glycerol, were investigated for a non-enzymatic reaction
  product, formaldehyde. All three cryoprotectants
  demonstrated a direct relationship between increasing solvent molarity and
  increasing formaldehyde concentration which was independent
  of temperature and protein (bovine serum albumin). Medium composition
  significantly influenced the formaldehyde concentration with
  HTF > T6 > M16 = M2. The formaldehyde could be effectively
  removed by reduced glutathione, cysteine and dithiothreitol with cysteine
  being the most effective scavenging agent. A reaction mechanism for this
  scavenging is proposed. The combination of cysteine and cryoprotectant
  reduced the zona pellucida 'hardening' effect in mouse oocytes.

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