The activity of digestion enzymes on pteroylglutamic acid (folic acid) and pteroyl-hexa-glutamyl-glutamic acid (folic acid conjugate)

Abstract

1. 1. A conjugase activity (liberation of free folic acid from the conjugate) is not found in normal gastric juice at p H2 and 7. This confirms the results of Welch et al. They also found no free folic acid but they did not investigate whether the conjugate was changed by the enzymes. 2. 2. In our experiments it is clearly shown that the vitamin B c conjugate (pteroyl-hexaglutamyl-glutamate) from yeast is altered by incubation with normal hum̀an gastric juice and and by a glycerol extract of pig stomach mucosa at p H2 but not at p H7. No free folic acid however is formed and rat liver conjugase is not able to liberate free folic acid from the incubation product. This is not due to conjugate inhibitors. 3. 3. In our pernicious anemia patient, the gastric juice had a p H of 7. Tthe alteration of the conjugate could however not be demonstrated at p H7. therefore a striking difference in the utilization of the conjugate exists. The folic acid deficiency of pernicious anemia patients may be explained by the inability to convert the conjugate as the p H in the stomach is 7 and the duodenal juice can not liberate free folic acid directly. 4. 4. The folic acid deficiency in non-tropical sprue can not be explained however in the same way, the p H of the stomach juice being the same as of normal juices. 5. 5. Normal duodenal juice has no conjugase activity. As the duodenal juices were always contaminated with gastric juice it was not possible to investigate whether the duodenal juice has the same conjugate converting at p H2 as the stomach juice. 6. 6. In the pig, free folic acid can be formed from the conjugate by pancreas enzymes.