Picolinic carboxylase activity in rat liver and kidney. I. Influence of growth, sex, gestation, lactation, and nutritional imbalance.
Picolinic acid (PA) is a metabolite of tryptophan that chelates trace metals, including zinc. Several recent observations have suggested a role for PA in zinc metabolism. The enzyme responsible for its formation is picolinic carboxylase (PC). We have measured PC in rats under a variety of conditions, using tissues that play a role in zinc metabolism. PC activity was demonstrated in liver and kidney and was not detectable in pancreas and brain. Activity was most pronounced in kidney. In male suckling rats, PC increased gradually, reaching maximum levels on the 21st day of life. Only liver PC showed marked variations under different physiological conditions. Liver PC was higher on the 21st day of life than in adulthood. It was higher in female than in male adult rats. In pregnant rats, liver PC decreased gradually toward the end of gestation, reaching the lowest point near delivery; however, a 12-fold increase occurred during lactation. Liver PC activity of rats with symptoms of pellagra showed a fivefold increase over controls with similar body weight, whereas liver PC of chronically starved rats showed only a twofold increase over controls with twice their body weight.
D000367:Age Factors; D000818:Animals; D002262:Carboxy-Lyases / Q000378:metabolism*; D005260:Female; D007668:Kidney / Q000201:enzymology*; D007774:Lactation; D008099:Liver / Q000201:enzymology*; D008297:Male; D010383:Pellagra / Q000201:enzymology; D011247:Pregnancy; D051381:Rats; D011919:Rats, Inbred Strains; D012737:Sex Factors; D013217:Starvation / Q000201:enzymology
D002262:Carboxy-Lyases; C022401:picolinic acid carboxylase