Biotin Flashcards
How and where biotin is absorbed?
a) Biotin is absorbed in it’s free form via facilitated diffusion. However, the protein bound coenzyme form, biocytin, undergoes a process where biotin is removed from the protein via an enzyme biotinase, where is it then absorbed in the jejunum.
What is the biochemical function of Biotin?
Biotin functions as a cofactor for four carboxylase enzymes, which transport CO2 (carboxyl units) to various substrates. These enzymes are needed in fatty acid synthesis (acetyl-CoA carboxylase), gluconeogenesis (pyruvate carboxylase), propionate metabolism (propionyl-CoA carboxylase) and branched-chain a.a catabolism (3-methylcrotonyl-CoA carboxylase).
What are good source of Biotin and what is the DRI?
a) Liver and smaller amounts in fruits and meats.
b) 25mcg/day in 14-18 F/M and 30mcg in all other groups.
How do we determine/measure Biotin deficiency?
Common methods are measurements of serum concentration and urinary excretion (24hr collection). However, the most valid indicators of biotin status are abnormal decreased urinary excreted biotin and an abnormal increased urinary excreted 3-hydroxyisovalerate acid.
