22/23.Folic Acid (B9) Flashcards
what are folic acid build up by?
pteridine ring, P-aminobenoic acid, glutamic acid
Draw the structure of folic acid
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characteristics of folic acid:
Yellow, slightly soluble in water in acid form, soluble in salt
What is the dietary form?
Polyglutamate, must be hydrolysed to monoglutamate (circulating form) for absorption through intestinal epithelium by the pancreatic enzyme; pteroylpolyglutamate hydrolase.
Storage?
50% in the liver, microbial production
Active form?
Folic acid is not the active form, it has to be reduced to dihydro folic acid by folic acid reductase, then reduced again with dihydro folic acid reductase to tetrahydrofolic acid (FH4).
Excretion:
Urine (small part, less than intake) Feces (bigger part, more than intake)
what is the biochemical role?
It is an acceptor and donor of one-carbon fragments in a variety of reactions.
Some important one-carbon fragments:
N5,N10 - methylenetetrahydrofolic acid, N5-formyltetrahydrofolic acid, N10-formyltetrahydrofolic acid
Derivatives:
Thymine (methyl) , methionine(homocystein to methionine, methyl transferase), glycine (from serine, major source of one-carbon units)
Why do some animals get deficiencies?
They sre unable to synthesize pterdine rings, needs it from diet or microorganisms.
Symptoms of deficiency in specific species:
chickens: hypovitaminosis Pigs: need sulphonamides (drug) to get deficiency, analogous to the P-aminobenzoic acid, so it inhibits the microbial synthesis. Ru/Ca: Need other drugs like aminopterin or amethopterin, analogous to dihydrofolic acid, so it is a competitive inhibitor, trying to stop folic acid reductase.
General deficiency symptoms:
Anemia- can be a result of diminished DNA synthesis because it requires FH4, slow growth - bad for meat production (muscle), leukemia.
