ABSTRACT
The two key enzymes, methylenetetrahydrofolate reductase and methionine synthase involved in methionine synthesis from homocysteine were studied in atherogenic diet fed mice. Methylenetetrahydrofolate reductase activity was elevated while methionine synthase was impaired in atherogenic diet fed group. Impaired methionine synthase activity would adversely affect the methionine synthesis from homocysteine, resulting in a rise in the homocysteine levels, which are atherogenic. This is reflected by the increased levels of very low density and low density lipoprotein cholesterol values and a higher ratio for total cholesterol to high density lipoprotein cholesterol.
Subject(s)
5-Methyltetrahydrofolate-Homocysteine S-Methyltransferase/metabolism , Animals , Diet, Atherogenic , Folic Acid Deficiency/enzymology , Homocysteine/blood , Male , Methylenetetrahydrofolate Reductase (NADPH2) , Mice , Mice, Inbred C57BL , Oxidoreductases Acting on CH-NH Group Donors/metabolismABSTRACT
Metabolic changes in the folic acid and their conjugated polyglutamyl derivatives have been studied in streptozotocin-induced diabetic rats. Conjugated folates which constituted about 70% in normal rat liver get rapidly hydrolysed to simple unconjugated forms as the diabetes progressed leaving behind only 2% after 25 days of the onset of diabetes. Chromatographic analysis shows significant alterations in the formyl- and methyltetrahydrofolate derivatives and their polyglutamylation profiles. A 7-8 fold higher urinary excretion of mainly methyltetrahydrofolate is also observed in diabetic rats.