Vitamin B7/H - Biotin

Question 1

biotin function

Answer 1

prosthetic group - binds to enzymes by forming an amide link (peptide is the type used here) to an amino group of Lysine BIOTIN + LYSINE => BIOCYTIN (prosthetic gr.)

Question 2

how is biotin transported around the body

Answer 2

biocytin from food is degr. by proteases (give off Lys) to biotin, which is passively absorbed to the liver to be synthesized into biotin enzyme, then tp. to other organs too for activity (carboxylation)

Question 3

synthesize biotin into biotin enzyme

Answer 3

biotin + lysine + protein enzyme = biotin enzyme

• amide link btw them COOH+NH2 -> CO-NH (+ H2O)

Question 4

excretion

Answer 4

biocytin -Biocytinase-> biotin (+Lys), conjugate to be excreted in the form of biotinsulphoxide

Question 5

antivitamin

Answer 5

avidine is found in egg yolk, and can bind biotin to make complex which cannot be absorbed

Question 6

biochemical role of biotin

Answer 6

carboxylase enzyme

• *1.** pyruvate -> OAC (GNG, activates protein in hair+fingernail cells)
• *2.** AcCoA -> MethylmalonylCoA (FA synthesis)
• 3.** propionylCoA -> methylmalonylCoA-> succinylCoA(TCA to make OAC)* ->GNG, RU esp.

Question 7

deficiency

Answer 7

can be caused by avidine, deficiency cause hair loss in all spp.

human: dermatitis and hair loss

Question 8

esp. affected spp.

Answer 8

• *rats**: hair loss, dermatitis
• *pultry, turkey**: low microbial synthesis cause deficiency -> low feathering, dermatitis, reduces egg production.
• *pigs**: hair loss, scaliness: foot and mouth disease(infectious)
• *horses**: damaged hooves due to granulation in food and feed decr. biotin uptake