Uridine Nucleosidase from Malt. W. J. Lee, Department of Agronomy, University of Wisconsin, Madison, and N. Prentice, U. S. Department of Agriculture, Agricultural Research Service, Cereal Crops Research Unit, Madison, WI 53705. J. Am. Soc. Brew. Chem. 45:0131, 1987.

Uridine nucleosidase (EC 3.2.2.3) has been purified from malt by a factor of over 900 by combined ammonium sulfate precipitation, calcium phosphate gel treatment, Trisacryl M diethylaminoethyl chromatography, gel filtration, and preparative electrophoresis. The enzyme had a temperature optimum of about 60° C and pH optimum of 7.5. The apparent molecular weight of the enzyme was approximately 117,000, the pI was 6.3, the K_m for uridine was 0.1 mM, and the activation energy was 6.5 kcal/mole. Uridine nucleosidase showed a very narrow specificity, being active only against uridine.

Keywords: Brewers mash, Enzyme parameters, Malt, Uracil formation, Uridinase