Gamma-glutamyl transpeptidase and its multiple forms in the tissues and sera of normal dogs

The total gamma-glutamyl transpeptidase activity and the proportions of its multiple forms in canine tissues and serum have been measured. The kidney showed the greatest activity, followed by the pancreas and small intestine. After separation by cellulose acetate electrophoresis, two main areas of activity were observed in tissues, an insoluble fraction which remained at the origin and a soluble fraction which migrated towards the anode. The soluble fraction was divisible into six zones differing in mobility and, with the exception of liver and lung, the tissues differed in the distances migrated by these soluble fractions. Serum gamma glutamyl transpeptidase formed one zone corresponding to the soluble fraction of liver and lung. The separation of the multiple forms is of potential value in determining the source of increased serum activities of the enzyme in the dog.