STUDIES ON FOLIC ACID METABOLISM:- ENZYMATIC MECHANISM, METHYL FOLATE BLOOD AND THE INTERRELATIONSHIP OF FOLATE AND VITAMIN B12

Abstract

The aim of this study was to collect further information about the metabolic interrelationships of vitamin B12, methionine, homocystine and protein on folate metabolism. Both animal and human studies were carried out during this investigation. The following folate requiring enzymes were studied in vitamin B12 deficient rats;- formiminotransferase, methylene THF reductase and B12 transmethylase. These enzymes were also studied in methionine and homocystine supplemented rats. Throughout the study, there was no evidence to show that the activity of formiminotransferase was affected by vitamin B12, methionine or homocystine. Results obtained for methylene reductase revealed that the activity of this enzyme was not affected by vitamin B12 but was affected by methionine and homocystine. The activity of methylene reductase was found to be repressed when methionine was fed to vitamin B12 deficient rats, On the other hand, when homocystine was fed instead of methionine, the activity of this enzyme was increased. The results obtained for B12 transmethylase showed that both vitamin B12 and homocystine affect the activity of this enzyme. In all the vitamin B12 depleted rats, there was a marked significant reduction in the activity of this enzyme. When homocystine was fed to the vitamin B12 depleted rats, the activity of this enzyme was increased. Other two parameters measured in these rats were hepatic folate and hepatic vitamin B12. Results revealed that both dietary vitamin B12 and dietary methionine had a sparing action on hepatic folate but this was not the case of homocystine. On the other homocystine had a sparing action on hepatic vitamin BI2. The interrelationship of protein, vitamin B12 and folate metabolism was investigated in both healthy and protein malnourished children aged 1-5 years. Results revealed that serum proteins and serum folate are significantly lowered in protein malnutrition while serum vitamin B12 concentration was higher in protein malnutrition. Erythrocyte folate concentration was also found to be higher in protein malnutrition. When serum vitamin B12 levels of newly delivered mothers were compared with their new born babies, it was found that the new born babies had higher vitamin B12 concentration than their mothers. This study has been able to show that there is enough evidence to suggest that there is metabolic interrelationship among vitamin B12, methionine, homocystine, protein and folate and they all in one way or other affect each other metabolism.