Effectiveness of taurine in protecting biomembrane against oxidant.

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Abstract
The effect of taurine in protecting biomembrane attacked by hypochlorous acid (HOCl) was examinded using canine erythrocytes which had been pre-treated with HOCl. In the treatment, most of the HOCl was consumed as a result of its reaction with a number of electrophilic substances, such as free amino groups (-NH2) in the membrane, whereas hemoglobin inside the cells was not oxidized. The lysis of HOCl-treated erythrocytes was dependent on the concentration of HOCl and on the incubation time at 37°C. Taurine inhibited the lysis at 37°C in a dose dependent manner. During the incubation of HOCl-treated erythrocytes with taurine, an appreciable amount of monochlorotaurine (TauNHCl) was detected in the supernate. This suggests that taurine might remove the oxidized chlorine from HOCl-treated erythrocytes, resulting in the production of TauNHCl. The effect of taurine on the removal of Cl+ moiety was further examined using Sepharose gel with free amino groups. Taurine removed Cl+ moiety from HOCl-treated Sepharose gel, and the yield of TauNHCl depended on the concentration of taurine and the incubation time. These results indicate that taurine might inhibit the hemolysis by scavenging the oxidized chlorine moiety from the HOCl-treated erythrocytes.Inhibition of the HOCl-induced hemolysis was also observed with other amino acids. The concentrations of taurine, α-alanine, β-alanine and glycine required for 50% inhibition of the lysis were 18, 30, 34, and 40 mM, respectively; thus taurine was the most effective inhibitor of all the amino acids. These results clearly indicate that taurine could be effective in inhibiting the biomembrane damage caused by HOCl.