GLYCOLYTIC ENZYMES IN THE TISSUES OF A SALMONOID FISH (SALMO GAIRDNERII GAIRDNERII)

Abstract

Glycolysis in various tissues of the steelhead trout (Salmo gairdnerii gairdnerii) has been studied in vitro using tissue extracts and homogenates. Of the tissues examined, skeletal muscle, heart muscle, liver and kidney, only heart muscle homogenate was found to be capable of converting free glucose to lactic acid without added hexokinase. Low hexokinase activity or low hexokinase activity coupled with adenosine triphosphatase activity accounted for the failure of the other tissue homogenates to attack glucose.Qualitative and quantitative studies have indicated the presence of hexokinase, phosphoglucoisomerase, phosphofructokinase, aldolase, glyceraldehyde-3-phosphate dehydrogenase, phosphoglyceromutase, enolase, pyruvic kinase, and lactic dehydrogenase in the various fish tissues examined. Except for hexokinase and phosphofructokinase, the activities of the glycolytic enzymes of skeletal muscle were found to be 10 to 100 times greater than those of the same enzymes in the other tissues tested.Diphosphopyridine nucleotide (DPN) and adenosine diphosphopyridine (ADP) were cofactors and iodoacetate and fluoride plus phosphate inhibitors of enzymes of the fish glycolytic systems.It can be concluded from this study that the Embden–Meyerhof glycolytic pathway functions in tissues of the anadromous salmonoid S. gairdnerii gairdnerii.