PLATELET-ACTIVATING-FACTOR ACETYLHYDROLASE (PAF-AH) IN HUMAN KIDNEY

1. PAF-AH activity in human kidney (cortex and medulla) has been demon strated and shares the following properties. 2. Does not require the p resence of Ca2+ and appears to be different from phospholipase A(2). 3 . The pH optimum shows a peak at 7-7.4. 4. It is stable for 4 days at -30 degrees C. 5. It is mainly distributed in the microsomal fraction. 6. The apparent K-m, values of the enzymes of cortex and medulla are 0.553 and 0.207 mu M, respectively and distinct from serum PAF-AH (1.4 39 mu M). 7. The apparent molecular weight values are 60,000 and 25,00 0 for medulla and cortex, respectively and distinct from serum PAF-AH (94,000).