Riboflavin

Question 1

riboflavin forms

Answer 1

coenzymes: FMN and FAD
(flavin mononucleotide)
(Flavin adenine dinucleotide)

Question 2

how is FAD formed ?

Answer 2

a nucleotide is 3 components:
1. base
2. sugar
3. phosphate

FMN + AMP = FAD

Question 3

function 1 of riboflavin

Answer 3

add or remove 2 H

Question 4

3 examples of role 1 of riboflavin

Answer 4

succinate dehydrogenase
- succinate + FAD = fumurate + FADH2
pyruvate dehydrogenase
- pyruvate = acetyl CoA (FAD received 2H then donates to NAD+)
glutathione reductase
- GSSG + FADH2 = 2GSH + FAD

Question 5

what part of ECT is FAD in

Answer 5

complex 2 FADH2 = FAD

Question 6

riboflavin function 2

Answer 6

Required for metabolism of other vitamins; therefore if
low in riboflavin, have secondary deficiency of these
vitamins: vitamin B6, folate, vitamin A, niacin, choline.
e.g. Vitamin B6 -> coenzyme (PLP) this reaction requires FMN

Question 7

food sources of ribflavin

Answer 7

milk light sensitive so glass bottles lose activity, while grains, enriched grain, meat/alts
riboflavin is stable to heat

Question 9

EAR riboflavin

Answer 9

M: 1.1mg
W: 0.9mg

Question 10

RDA riboflavin

Answer 10

M: 1.3mg
W: 1.1mg

Question 11

UL for riboflavin

Answer 11

none

Question 12

riboflavin deficiency

Answer 12

nonspecific, symptoms of multiple vit deficiency

Question 13

test for riboflavin status

Answer 13

1. urinary
2. erythrocyte glutathione reductase stim test: activity coefficient “EGRAC”
   - measure activity in hemolysed RBC w and w/out added FAD
   - % above unstimulated enzyme activity
   - AC over > 1.4 shows deficiency (stimulated more than 40% over original activity)