ENZYMES OF THE γ‐GLUTAMYL CYCLE IN THE CHOROID PLEXUS AND BRAIN

Abstract —The presence of enzymes of the γ‐glutamyl cycle in the bovine and rabbit brain and choroid plexus is described. The activities of γ‐glutamyl transpeptidase, γ‐glutamyl cyclotransferase and γ‐glutamyl‐cysteine synthetase in the choroid plexus were found to be higher than in the brain. The activity of γ‐glutamyl transpeptidase in the choroid plexus was many times higher than the activity of the other enzymes. Brain and choroid plexus γ‐glutamyl transpeptidase were activated by Na + and K + . Both brain and choroid plexus showed only a very limited capacity to metabolize [ 14 C]5‐oxoproline to 14 CO 2 .