Neuraminidase (Sialidase: Acylneuraminyl hydrolase; EC 3.2.1.18) From Arthrobacter ureafaciens lyophilised powder with salts. The salts are composed of sodium-potassium phosphate to give a solution of 10 mM phosphate buffer (pH 7) when enzyme is reconstituted with water to make activity of 1 unit per ml. Activity: >60 units/mg protein for NAN-lactose >25 units/mg protein for bovine submaxillary mucin >20 units/mg protein for colominic acid Protein is determined by the method of Lowry et al. with bovine albumin as a standard.6 Unit definition: One unit will liberate 1,0 µmole of N-acetyl-neuraminic acid (NANA) per minute at pH 5,0 at 37 °C, using either one NAN-lactose, bovine submaxillary mucin, or colominic acid as a substrate.