Uridine phosphorylase from Salmonella typhimurium (StUP) catalyzes the reversible phosphorolysis of uridine with the formation of ribose-1-phosphate and uracil.http://www.creative-enzymes.com/product/Uridine-Phosphorylase-From-Salmonella-Typhimurium-Recombinant_1860.html