Vitamin B2

Question 1

Wauburg and Christian

Answer 1

Isolated from yeast a substance that had a yellowish (flavis) glow; named it “yellow enzyme”, which could be dissociated into a protein part and a non-protein part.

Question 2

Paul Karrer

Answer 2

Isolated and crystallizes vitamin B2; recognizes it as the yellow enzyme.

Question 3

Riboflavin

Answer 3

Compound found to contain ribose-like side chain and is yellow (flavus) thus named riboflavin.

Question 4

1937 Nobel Prize in Chemistry

Answer 4

Paul Karrer- Awarded “for his investigations on carotenoids, flavins, vitamins A and B2.”

Question 5

Riboflavin

Answer 5

Ribitol + Flavin

Question 6

Flavin mononucleotide (FMN)

Answer 6

Or Riboflaivn phosphate…. added a phosphate to the end

Question 7

Flavin adenine dinucleotide

Answer 7

added a second Nitrogen base and ribose sugar

Question 8

Food sources

Answer 8

Dairy products & Meats

Question 9

Riboflavin absorption

Answer 9

Take of the phosphate groups with…. FMN phophatase, FAD pyro-phosphatase, alkaline phosphatase

Question 10

Main circulating form

Answer 10

riboflavin

Question 11

Bound to

Answer 11

albumin in plasma… sometimes to immunoglobulins IgA, IgG, IgM

Question 12

Tissue uptake and excretion

Answer 12

Free riboflavin is taken up by cells through carried mediates process. RFT1 or RFT2. Very little riboflavin is sto red. Excreted in urine, primarily as riboflavin

Question 13

Functions

Answer 13

Functions metabolically as the essential component of the coenzymes FMN and FAD. FMN and FAD serve as intermediaries in electron transfer in the oxidation-reduction reactions. As coenzymes, FMN and FAD are often bound to enzymes: oxidases & dehydrogenases.

Question 14

Oxidase

Answer 14

Pyridoxal oxidase & monoamine oxidase– FAD

Question 15

Dehydrogenase

Answer 15

Dihydrolipoyl dehydrogenase, succinate dehydrogenase, glycerol-3-phosphate dehydrogenase, fatty acyl-coA dehydrogenase– FAD…. NADH dehydrogenase– FMN!!!

Question 16

Oxidoreductase

Answer 16

Glutathione reductase- FAD

Question 17

Scientific Waterfall

Answer 17

B2

Question 18

Plays role in B6 excretion

Answer 18

Converting pyridoxal to 4-pyridoxic acid with FAD taking a hydrogen to make FADH

Question 19

Enzyme complex role

Answer 19

Reduced lipoamide is oxidezed by the flavo (FAD) dependent enzyme dihydrolipoyl dehydrogenase.

Question 20

Folate cycle role

Answer 20

5, 10-CH2THF –> 5-CH3THF with MTHFR

Question 21

Redox reactions of riboflavin

Answer 21

Goes from 2 double bonded nitrogens to 2 NH in two reactions.

Question 22

Glutathione reductase

Answer 22

An important antioxidant enzyme

Question 23

Status assessment

Answer 23

Erythrocyte glutathione reductase activity, stimulation test with FAD

Question 24

Normal

Question 25

Deficient

Answer 25

> 40% stimultation

Question 26

Deficiency

Answer 26

Rare in US. Most common in alcoholics

Question 27

Clinical symptoms

Answer 27

Glossitis. Angular stomatitis. Dermatitis. Weakness.

Question 28

EAR

Answer 28

1 mg

Question 29

Supplements

Answer 29

Yellow/ orange color of vitamin supplements usually due to riboflavin. High-does supplemental riboflavin intake causes the urine to change color, deepening from light yellow to a brighter yellow/ orange color.

Question 30

Toxicity

Answer 30

Doubtful. Human GI tract can only absorb ~30mg of a single oral dose