Abstract
The synthesis of L-tryptophan from indole and DL-serine catalyzed by tryptophan synthetase entrapped in cellulose triacetate fibres was investigated using batch and continuous feed recycle reactors.
Tryptophan productivity, expressed as mg of tryptophan per hour per g of fibres, was 34 and 4 for the batch and the continuous reactor respectively; the final conversion of L-serine was 57% and 6.6%; practically all the indole was converted to tryptophan in the two reactors. Pyridoxal-5'-phosphate was necessary for the activity of the entrapped enzyme. D-Serine showed a slight inhibitory effect, was not utilized by the entrapped enzyme and after racemization at 160°C was reused. By increasing the molarity of the buffer used in the reaction mixture a decrease of tryptophan productivity was observed. The product, isolated from the reaction mixture was pure L-tryptophan.
