Method for preparing L-tryptophan by enzymatic conversion

Abstract

The invention belongs to the technical field of medicine and biology and particularly relates to a method for preparing L-tryptophan by enzymatic conversion. The method, of which L-tryptophan is prepared from mixed amino acids containing L-serine, comprises the following steps: mixing the high-activity genetic engineering bacteria of L-tryptophan synthetase or L-tryptophanase with the conversion solution of the mixed amino acid containing L-serine; carrying out the enzymatic reaction at the temperature of 30 to 45 DEG C; and then, separating the converted products by the isoelectric point crystallization method or the method combining isoelectric point crystallization and ion exchange resin to obtain high-purity L-tryptophan. The method solves the problems of the separation and overall development of L-serine in the mixed amino acids by obtaining L-serine products with wider applicable range and higher added value, therefore, the invention has the advantages of wide material availability, low price, convenient operation, short conversion time, low production cost and the like.

Description

1. Technical field

[0001] The invention belongs to the technical field of medicine and biology, and in particular relates to an enzymatic conversion preparation method of L-tryptophan. 2. Background technology

[0002] Tryptophan, also known as α-amino-β-indolepropionic acid, is an amino acid discovered and isolated by Hopkins and Cole in 1902. It has two isomers, D- and L-, and only L-tryptophan exists naturally. L-tryptophan plays an important role in the growth, development and metabolism of humans and animals, so it is widely used in the fields of medicine, food and feed.

[0003] According to current literature reports, the preparation method of L-tryptophan mainly contains following three kinds:

[0004] 1. Fermentation method

[0005] The fermentation method to produce L-tryptophan can be roughly divided into: direct fermentation method and precursor addition fermentation method.

[0006] The commonly used L-tryptophan-producing bacteria in the direct fermentation...