Purification of the active phosphatase found in dog faeces

IT was observed [Armstrong et al., 1934] that a phosphatase, active at pH 9-6, was present in dog faeces.The activity of the faeces is variable but usually exceeds that found in the case of intestinal mucosa which is the tissue having, weight for weight, the greatest phosphatase activity in the body.It seemed worth while to attempt to isolate, if possible, a crystalline enzyme from this cheap and unlimited source.Whilst a crystalline material was not obtained, the degree of purification reached was sufficiently great to warrant pub- lication in view of the fact that the work must now be temporarily abandoned.The underlying principles involved in the procedures employed were as follows: preparation of a water-clear aqueous extract of the faeces, salting out the protein from this extract, solution of the protein and removal of foreign material by acidification and adsorption, reprecipitation of the protein with minimum contamination by inorganic salts.These procedures presented con- siderable difficulty for two reasons: (1) the colloidal nature of concentrated mixtures of faeces and water and (2) the fact that the phosphatase active at PH 9-6 is unstable in acid media.No difficulty was ever encountered owing to