Studies in immunochemistry. 14. The isolation and properties of substances of human origin possessing blood-group B specificity.

abundant in the spleen, the system we have described is absent from that organ in the mouse and has so far been found only in the liver. This finding agrees with the results of tissue-slice experiments. The stability of fl-glucuronidase to storage, to acetone precipitation and to armmonium sulphate fractionation is also in marked contrast with the above results. A purified spleen P-glucuronidase preparation (kindly given by Dr G. T. Mills) could not replace the liver suspension in the synthetic system. Although this result might be explicable if the system comprised more than one enzyme, we have found that saccharate and saccharic 1-+ 4-lactone (the most powerful P-glucuronidase in-hibitor known) do not interfere with the synthesis. Finally, Dr G. A. Levvy has very kindly studied the effect of a pure solution of the factor upon the hydrolysis ofphenolphthalein glucuronide by mouse liver fi-glucuronidase. A 4 x 10-6M solution of the factor did not inhibit the hydrolysis of 12-5 x 10-5M or 6-25 x 10-5m substrate (within experimental error), and he concludes that the factor cannot be a substrate for P-glucuronidase. Taken together, the evidence appears to show conclusively that this enzyme is not concerned in the formation of glu-curonides by the present system. SUMMARY 1. Conditions are described for the study of glucuronide synthesis in liver suspensions. 2. Glucuronide synthesis could not be demonstrated unless a boiled extract of liver was also present. The reaction product has been shown to be a glucuronide. 3. The active factor obtained from liver by boiling or by trichloroacetic acid extraction was destroyed by acid and alkali and by phosphatase preparations. 4. The effect of pH and certain other conditions upon the synthesis has been studied. 5. The enzymic activity of the suspensions appeared to be located in the particulate material of the cell cytoplasm. 6. The synthesis in suspensions is compared with that in liver slices, and the possible relationship of ,-glucuronidase to the first-named process discussed. REFERENCES The isolation and properties of human blood-group substances which possess A, H and Lea specificity from ovarian cyst fluids are described by King & (1952a, b), and certain of the materials were shown to be substantially homogeneous both physically and chemically. The present paper describes the isolation of substances having B specificity from the same source, and records their chemical, physical and serological properties. Earlier work in this field is reviewed by Morgan (1947), Bray …