The micro-estimation of benzoic and hippuric acids in biological material.

4. Incubation of homogenates in acetate buffer leads to a progressive release of enzyme from the granules to the solution. This does not occur in citrate buffer. 5. In concentrated homogenates, the presence of the insoluble enzyme fraction can lead to false results for the total activity. 6. The pH-activity curves for the hydrolysis of phenolphthalein glucuronide in acetate buffer by the soluble and insoluble fractions are identical in having peaks at pH 4-5 and 5-2. 7. Saccharate inhibits the enzyme in the granules without affecting its release to the solution on incubation in acetate buffer. 8. The significance of these findings in the assay of glucuronidase is discussed, with particular reference to tissues in varying states of proliferation.