Comparative studies on red blood cell glucose phosphorylating activities of mammals

1. ATP-D-hexose-6-phosphotransferase activity was measured in red blood cells of man, rabbit, pig and cow. Mean values ranged from 0.60 to 1.06 units/g haemoglobin and no significant difference was obtained with different glucose concentrations. 2. The characteristics of glucose phosphorylating activities in red blood cells of the species studied were similar. 3. Chromatography on DEAE column revealed two different glucose phosphorylating activities in red cells of man, rabbit and pig, and only one in cow red cells. 4. The first hexokinase activity is the predominant form and is saturated with low glucose concentrations; the second is noticeably marked at high glucose concentrations.