ENZYMES OF FRUCTOSE METABOLISM IN LIVER OF SOME VERTEBRATES

1. 1. In livers of vertebrates, enzyme levels of fructose metabolism were measured-in particular, ketohexokinase, aldolase, triokinase, aldehyde dehydrogenase, alcohol dehydrogenase (NAD), alcohol dehydrogenase (NADP) and sorbitol dehydrogenase. 2. 2. Results for the following animals are presented: Tinca tinca, Cyprinus carpio, Triturus cristatus, Rana temporaria, Rana esculenta, Bufo bufo, Natrix natrix, Testudo hermanni, Lacerta agilis, Columba sp., Anas platyrhynchos, Gallus gallus L., Rattus, Wistar AF/Han. and Lepus cuniculus. These results are compared to those with Homo sapiens. 3. 3. Ketohexokinase, the enzyme catalysing phosphorylation of fructose to fructose 1-phosphate, was found only in livers of man, mammals and birds. Our findingsshow that the typical pathway of fructose exists only in homoeothermic vertebrates. 4. 4. The other enzymes of fructose metabolism were found in the liver of all vertebrates, with the exception of amphibian liver which does not contain triokinase activity. © 1969.