A COMPARATIVE STUDY OF NUCLEOTIDE METABOLISM IN FISH LIVER

Abstract

Anion exchange chromatography has been used to separate the acid-soluble nucleotides of the livers of several species of fish including salmon taken in fresh and salt water. This technique has produced an elution pattern of nucleotides similar to that obtained from poultry and mammalian liver. Two of the uridine-containing areas eluted from the column have been investigated in detail using enzymatic, chromatographic, and colorimetric techniques. The first of these two adjacent peaks was found to contain N-acetylglucosamine and N-acetylgalactosamine, whereas the second contained glucose and galactose. In both cases, the glucose moiety was the major constituent.Samples of liver taken from silver salmon were fractionated and two of the enzymes acting on UDP glucose were identified. The first of these enzymes, UDPG dehydrogenase, was partially purified and the product of the reaction with UDPG was identified as UDP glucuronic acid. The second enzyme, UDPGal-4-epimerase, was separated from the dehydrogenase and characterized by enzymatic assay using UDP galactose as substrate.