Deficiency of two enzymes of galactose metabolism in kangaroos

THE starting point of the investigation reported here was the observation by one of us of diarrhoea and occasional cataract formation in bottle-fed orphan pouch-young kangaroos. As kangaroo milk has a very low lactose content1–3 and the intestinal lactase content of pouch-young kangaroo is also low4, we thought that these marsupials may not utilise galactose, present mainly as polygalactan in milk, by the usual pathway involving galactokinase (E.C. 2.7.1.6) and galactose-1-phosphate uridyl transferase (E.C. 2.7.7.12) (transferase). With this postulate, and the role of deficiency of these two enzymes in human cataractogenesis in mind, galactokinase and transferase were assayed in haemolysates from the grey (Macropus giganteus) and the red kangaroo (Megaleia rufa).