EFFECTS OF NAD OR NADP ON THE STABILITY OF LIVER AND PECTORAL MUSCLE ENZYMES IN 3-ACETYLPYRIDINE TREATED QUAIL BY HEAT AND TRYPSIN

(1) The effects of long term treatment with 3-acetylpyridine on the st ability of enzymes towards heat and trypsin treatment were studied. (2 ) In the liver NAD or NADP provided a similar degree of protection aga inst heat inactivation at 55 degrees C for 6-phosphogluconate dehydrog enase (24%), glyceraldehyde-3-phosphate dehydrogenase (24%) and malic enzyme (20%), low level of protection of lactate dehydrogenase (13%) b ut didn't affect acetylcholinesterase at all. In the muscle, however, there was substantial protection against heat inactivation by coenzyme of glyceraldehyde-3-phosphate dehydrogenase (52%), an intermediate le vel of protection of lactate dehydrogenase (25%), low level of protect ion of 6-phosphogluconate dehydrogenase (17%) and malic enzyme (17%) a nd almost no protection of acetylcholinesterase. (3) In the susceptibi lity towards trypsin a low but similar degree of protection for dehydr ogenases by coenzymes was observed in the liver whereas in the muscle there was substantial protection against trypsin inactivation by NAD o f glyceraldehyde-3-phosphate dehydrogenase, an intermediate level of p rotection of 6-phosphogluconate dehydrogenase and malic enzyme and ver y little protection of lactate dehydrogenase but no protection of acet ylcholinesterase. Among enzymes tested, glyceraldehyde-3-phosphate deh ydrogenase showed the greatest protection against heat and trypsin ina ctivation by NAD. (4) The results suggest that the effect of 3-acetylp yridine treatment on the stability of muscle glyceraldehyde-3-phosphat e dehydrogenase appears to be quits specific and selective. (C) 1998 E lsevier Science Ltd. All rights reserved.