LARGE-SCALE PRODUCTION OF A SOLUBLE HUMAN BETA-1,4-GALACTOSYLTRANSFERASE USING A SACCHAROMYCES-CEREVISIAE EXPRESSION SYSTEM

We report in this communication the first large-scale heterologous exp ression of a glycosyltransferase in yeast. A soluble form of a human b eta-1,4-galactosyltransferase (EC 2.4.1.38) was expressed using a Sacc haromyces cerevisiae expression system. Fermentation technology afford ed the means to increase the expression level of the beta-1,4-galactos yltransferase up to a concentration of 700 mU/liter. The enzyme was pr oduced at a scale of 200 units. The recombinant soluble enzyme was pur ified 766-fold to a specific activity of approx. 2 U/mg using a purifi cation protocol based on sequential affinity chromatography on N-acety lglucosaminyl- and alpha-lactalbumin-Sepharose, respectively. This stu dy demonstrates that heterologous expression of a glycosyltransferase is possible on a large scale and offers an alternative to natural sour ces like human breast milk or bovine colostrum. (C) 1995 Academic Pres s, Inc.