Abstract: A kinetic model describing the pathway for the L-cysteine enzymatic synthesis by Pseudomonas sp. strain TS1138 has been developed. In the synthesis pathway, both the L-cysteine synthetase (CS) and the L-cysteine desulfhydrase (CD) were involved with the kinetic model based on Michaelis-Menten type kinetics, and also on noncompetitive inhibition of the CS by L-cysteine. From the determination of intermediates and end products during the process of L-cysteine enzymatic synthesis, with the kinetic model, metabolic control analysis (MCA) of the pathway was carried out. From the kinetic model, the elasticity coefficients and the flux control coefficients were calculated through the pathway. It was found that there is a shift in the flux control from the CS to the CD during the enzymatic reaction.

Key words: L-cysteine, kinetic model, metabolic control analysis, enzymatic synthesis