The action of enzymes on chlorophenylalanines.

It is evident from this investigation that the bile pigment precursor content ofhuman erythrocytes is not greater than that associated with the corresponding amount of crystalline oxyhaemoglobin. Such a result could arise if either of two quite different conditions obtain. The minute yields of bile pigment might be caused artificially by the drastic chemical processes involved. Alternatively, bile pigment precursor may pass along with oxyhaemoglobin through all the steps of purification into the crystalline product, maintaining the original quantitative relations with the mother pigment which obtained in the original erythrocytes. This latter hypothesis appears unlikely, but no means are available at present of deciding which is the true interpretation. The suggestion that early changes in the breakdown of haemoglobin to bile pigments are initiated during circulation receives little support from the present experiments. It is possible that a more fruitful search for intermediates of pigment metabolism could be made in situations where the reticulo-endothelial system is overloaded with haemoglobin catabolic products, as in the spleen of patients suffering from haemolytic jaundice or poly. cythaemia. SUMMARY