[Glutamic acid decarboxylase in the brain, pancreas and kidneys. Comparison of its properties]

Comparisons of soluble and bound GAD activities in brain, pancreas, and kidneys were performed. In all three organs GAD was present in three forms: soluble GAD; GAD, the solubility of which was achievable by means of CHAPS detergent; and GAD, refractory towards the detergent affect. The activity of these three GAD fractions, each belonging to a different cellular compartment, proportionally differed. The ratio of free, bound, and irreversibly bound activity expressed in percentage was 63:21:15 in the brain, and 14:40:36 in the pancreas. In coincidence with the occurrence of autoantibodies to GAD from the brain under the condition of SMS, and that from the pancreatic beta-cells under the condition of IDDM, it is supposed that the conditions favourable for the origin of the immune response are rendered by GAD bound in membranes. In kidneys the proportions of free (15%) and bound GAD (29%) are complicated by until now unassessed factors, since their isolation from the free, eventually bound GAD causes an activity waste of 50% which supervenes following the homogenate separation by the use of centrifuge. Effect of ATP and chlorides displays both, different and common properties of GAD from the mentioned three organs. ATP inhibited the brain GAD and the renal supernatant GAD, whereas it activated GAD from the homogenate and sediment of the kidneys and the pancreatic GAD. Chlorides inhibited the brain and pancreatic GAD and activated the renal GAD. (Fig. 8, Tab. 1, Ref. 16.).