Flashcards in B6 Deck (13)
Interaction with tryptophan
Comes in 3 forms
Pyridoxine PN (most stable form, found in plants and supplements). Alcohol form.
Pyridoxal PL. Aldehyde form. Animal.
Pyridoxamine PM. Amine form. Animal.
All have 5' phosphate derivative
Binds to AA to make Schiff base.
Active phosphorylated form.
Liver main site of synthesis. RBC. 10% stored in liver. 80% stored in cell.
PLP food source hydrolyzed by zinc dependent phosphatase prior to uptake. Creates PL.
PL rephosphorylated in cell.
In blood: PLP bound to albumin (protect from phosphatase)
Unphosphorylated passively diffuse.
80% stored in muscle bound to glycogen
In RBC: PLP bound to hemoglobin
Interactions with other nutrients
Riboflavin maintains B6
Works with thiamin in Kreb's cycle.
Chicken, banana, fortified cereal.
Supplement: pyridoxine hydrochloride
Direct: plasma >30 nmol/L
Functional: tryptophan load test measures xanthurenic acid excretion (produced in deficiency)
Depression, cheilosis, anemia.
Can be caused my riboflavin deficiency.
Mg needed as well to convert PN to PLP.
Neuropathy, impaired reflexes.