Conversion of L-cystine and L-cysteine to taurin by the enzyme systems of liver cells

The kinetics of conversion of sulfur-containing amino acids L-cystine and L-cysteine to taurin by the enzyme system of cattle liver cells was studied, and a mathematical model was developed. It was shown that L-cystine and L-cysteine conversion obeyed the Michaelis-Menten equations of serial-sequential conversions with regard to inhibition by the final product and inactivation. The yield of taurin under the optimized conditions of L-cystine and L-cysteine conversion (temperature, 40 degrees C; pH 1.5 and 3.0, respectively; and addition of enzyme preparations in five equal portions at 2-h intervals) was in the range 80-85% of the substrate weight.