l-Phenylalanine inhibition as a method for measuring the intestinal component of alkaline phosphatase in dog serum

Abstract Inhibition studies with l -phenylalanine have been carried out on canine tissues extracted for liver and intestinal alkaline phosphatase. A high percentage inhibition (72%) of intestinal alkaline phosphatase (IAP) was confirmed and in addition a small but significant inhibition (19.5%) of liver alkaline phosphatase (LAP) was found under the conditions used. The principle of differential inhibition was used to set up a quantitative assay for the intestinal component of serum alkaline phosphatase; 11% IAP was found in fasting dog sera.