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. Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=11568