Abstract
After establishing the formation of NADH2 by algal urea dehydrogenase, some properties of the enzyme were examined. The enzyme has the optimum temperature at 35°C and inactivated by heating. At pH 7.6, its stability as well as activity is the highest. It is not effected by FAD and FMN, but activated by small amount of inorganic phosphate, by which ammonia dehydrogenase is inhibited. Tris-HCl buffer is suitable for assay. Cysteine has no effect on the activity, while increase of the optical density is brought about in the control containing no urea. Activity is more or less elevated by addition of boiled algal extract. Contrary to liver urea dehydrogenase, algal enzyme prefers NADP to NAD, although both are reduced. The enzyme is not adsorbed by DEAE-cellulose, similar to ammonia dehydrogenase, while purification to some extent is attained.
