Sulfuric acid magnesium salt (1:1) → aldehydo-D-Xylose

Participants

Reaction Conditions

Reaction Steps

Alternatively XI protein is isolated from Streptomyces rubiginosus strain C3 derived from S. rubiginosus ATCC 21,175 using the method described in U.S. Pat. No. 4,410,627, which is incorporated herein by reference. The strain is grown by submerged aerobic fermentation on a medium with the following composition (by percent weight) dextrose 9.0%, corn steep liquor (solids) 0.06%, diammonium phosphate 0.008%, magnesium sulfate 0.06%, antifoam (pluronic PL-61) 0.003%. The medium is sterilized at 121° C. for 45 min, cooled and adjusted to pH 5 6.8-7.0. The medium is inoculated with 14% (v/v) of an inoculm comprising the contents of a seed fermenter prepared with the S. rubiginosus strain. XI protein is extracted from the S. rubiginosus strain by adding 0.35% Maquat MC 1412 (Mason Chemical Co.) and 10 ppm of hen's egg lysozyme and agitating for 5 hr at 40° C., pH 6.3 to 6.6. The mixture is then filtered to provide a solution of unpurified xylose isomerase. The crude isomerase is purified by adsorption on DEAE-cellulose, filtering and washing the adsorbed product with 0.1M NaCl solution to remove impurities, and then desorbing by contacting with 0.45M NaCl solution. The pH of all solutions is maintained at 7.5 during the purification step. The solution of partially purified isomerase obtained thereby is mixed with 3 volumes of 95% ethanol at 0° C. to precipitate the isomerase. Perlite filter aid is added, the solids recovered by filtration, and air dried to provide a soluble XI preparation containing 2500 U/g. Specific activity of the preparation thus prepared is 40 U/mg of protein.

Provenance & Evidence