PURPOSE: To obtain the titled enzyme in the form of an aqueous solution, by culturing a microbial strain containing the titled enzyme, disintegrating the microbial cells at a low temperature, extracting the enzyme, heat-treating in the presence of sodium chloride or L-serine and removing residue and other proteins from the product.
CONSTITUTION: A microbial strain such as Escherichia coli MT-10242 (FERM BP-20) is cultured in a medium containing a carbon source, a nitrogen source, etc., and the microbial cells in the cultured liquid are mechanically disintegrated at a cell concentration of 30W60g/l at pH 6W10 and ≤30°C, preferably 5W15°C. After the disintegration treatment, the obtained suspension containing tryptophan synthase transferred from the cell is added with sodium chloride or L-serine and heat-treated at 40W45°C in the presence of the above additive. The heat- treated suspension is immediately cooled to ≤30°C and the residue of disintegrated cells and precipitated proteins other than tryptophan synthase are removed from the suspension to obtain the objective aqueous solution of the enzyme.
MATSUMOTO TOSHIO
YANAKA MAKOTO
NITTA KAZUNARI
