The estimation of histidine in urine and its excretion by normal and pregnant women.

1. Four diabetogenic ureides were examined for their power to inhibit alkaline phosphatase and were all highly active. Of ten related compounds examined, two were poor inhibitors of phosphatase although not diabetogenic and non-inhibiting for phosphatase. The anti-phosphatase activity seems to reside in a free 5-hydroxyl group. 2. This action on phosphatase has been demonstrated in the presence of plasma and blood and in tissue sections. It is reversible, non-competitive and unaffected by magnesium.