Micro Metabolism B Vitamins Chapter 9

Front 1

Sources of Thiamin

Back 1

Pork, Legumes, Whole fortified enriched grains, sunflower seeds

Front 2

Can Thiamin be effected/destroyed by any factors

Back 2

Destroyed by heat and alkaline pH

Front 3

What form is Thiamin found in animals foods?

Back 3

Thiamin Diphosphate aka Thiamin pyrophosphate

Front 4

Where is FREE Thiamin absorbed?

Back 4

absorbed in the jejunum and ileum

Front 5

How is the Thiamin Diphosphate converted to its free form

Back 5

intestinal phosphatase removes the phosphates

Thiamin pyrophsophokinase

Front 6

What are the factors that destroy Thiamin?

Back 6

Thiaminases (raw fish)

Polyhydroxyphenols (tea, coffee, blueberries, brussell sprouts)

These destroy the Thiamin ring, prevented in the presence of Vitamin C and citric acid

Alcohol also inhibits absorption

Front 7

Absorbed Thiamin is taken up where...

Back 7

in the liver phosphorylated to TDP

Front 8

What is the percentages of TDP VS TTP in the body?

Back 8

80% TDP

10% as TTP

Front 9

Is Thiamin carrier mediated?

Back 9

Yes

Front 10

What is the enzyme that converts Thiamin to it's coenzyme form TDP

Back 10

thiamin pyrophosphokinase

Front 11

What is the antithiamin factor that comes from raw fish? How can it be destroyed?

Back 11

Thiaminases

By heat

Front 12

What is the antithiamin factor that comes from coffee, tea, blueberries, brussel sprouts? How can it be destroyed?

Back 12

Polyhydroxyphenols they are stable in heat but can be inhibited by Vitamin C and citric acid

Front 13

Does alcohol effect Thiamin?

Back 13

Inhibited by alcohol

Front 14

What complexes is Thiamin's coenzyme TPP involved in?

Back 14

"Dehydrogenases"

1. Pyruvate dehydrogenase comlex

2. alpha ketoglutarate dehydrogenase complex

3. BCA dehydrogenase complex

Front 15

What does inhibition of Thiamin or it's coenzymes?

Back 15

prevents synthesis of ATP and acetyl CoA needed for synthesis of fatty acids, cholesterol,

and allows for accumulation of lactate, pyruvate, and alpha keto gluturate

Front 16

Pyruvate dehydrogenase complex overall reaction

Back 16

Pyruvate + NAD+ + Coa-->

Acetyl Coa +NADH + H+ + Co2

Front 17

Pyruvate Dehydrogenase complex, is _________ dependent. How?

Back 17

TPP dependent

C2 of the Thiazole ring forms a carbonion making it open to a neuleophilic attack from

pyruvate

alpha keto glutarate

and other alpha ketoacids

Front 18

What is the function of the Pentose Phosphate Pathway?

Back 18

Synthesis of Pentose sugars and NADPH

Front 19

Transketolase needs the enzyme...

Back 19

TPP for the Phosphate Pentose Pathway

Front 20

What is Thiamin (TPP) non coenzyme role?

Back 20

Nerve conduction

Front 21

RDA for Thiamin is based on...

Back 21

1. Urinary excretion

2. RBC transketolase activity

3. Thiamin intake data

Front 22

What is the difference between Dry and Wet Beriberi

Back 22

Dry is nerve

Wet is the heart

Front 23

What is the disease associated with the deficiency of Thiamin?

Back 23

BeriBeri

Front 24

What is the structure of Riboflavin?

Back 24

flavin molecule (isoalloxazine ring) with ribotol side chain

Front 25

What are the two coenzymes of Riboflavin?

Back 25

FMN AND FAD

Front 26

What are the food sources of Riboflavin?

Back 26

Milk and milk products, eggs, meat, legumes, liver

Front 27

Is Riboflavin effected by light/heat/acid/alkaline?

Back 27

Destroyed by sunlight

Resistant to heat, oxidation, and acid

Front 28

Riboflavin must be in _______ form for absorption

Back 28

Free form only

Front 29

Where is Riboflavin absorbed?

Back 29

Small intestine

Front 30

Is Riboflavin carrier mediated?

*** In large amounts?

Back 30

Yes saturable energy dependent

In large amounts passive absorption

Front 31

Does alcohol effect Riboflavin?

Back 31

Alcohol inhibits

Front 32

What substance stimulates absorption of Riboflavin?

Back 32

Bile

Front 33

In the liver Riboflavin.....

Back 33

is converted to FMN and FAD after absorption

Front 34

What enzymes convert Riboflavin in the liver?

Back 34

Flavokinase and FAD synthetase

Front 35

Free riboflavin is absorbed into..... by....

Back 35

Tissues by riboflavin binding proteins

Front 36

Where are the greatest sources of free Riboflavin that have been absorbed into the tissues found?

Back 36

Liver, kidney, and heart

Front 37

Within the cells of tissue Riboflavin is....

Back 37

converted to FMN and FAD

Front 38

When bound to it's apoenzyme Riboflavin is....

Back 38

a Flavoprotein

Front 39

What is the function of Riboflavin's coenzyme?

Back 39

FMN and FAD

Oxidation/reduction reactions

Front 40

Specifically how does FMN and FAD participate in oxidation/reduction reactions?

Back 40

The Isoalloxazine ring accepts/donates a pair of H one electron at a time--> FMNH2 and FADH2

Front 41

What are the functions of flavoproteins?

Back 41

1. Electron Transport Chain

2. Vit. B6 metabolism

3. Oxidative decarboxylation of pyruvate and alpha keto glutarate

4. B oxidation, acyl Coa Dehydrogenase

5. Synthesis of THF, cofactor form of folate

Front 42

The RDA of Riboflavin is based on

Back 42

1. Urinary excretion

2. Relation of diet to clinical symptoms of deficiency

3. RBC glutathione reductase

Front 43

What is the disease of deficiency of Riboflavin?

Back 43

Ariboflavinosis (no clear characterization)

Maybe be seen in excessive alcohol

Front 44

How do you test the nutriture of Riboflavin?

Back 44

Measure activity of erythrocyte FAD- dependent glutathione reductase with and without FAD addition

AC greater than 1.4 = deficiency

Front 45

What is the enzyme that used to assess both the RDA and the state of nutriture for riboflavin?

Back 45

Erythrocyte glutathione reductase

(FAD dependent)

Front 46

What is the name given tothe protein or enzymes that bind FMN and FAD?

Back 46

flavoprotein?

Front 47

What are the two forms of Niacin

Back 47

Nicotinic Acid

and Nicotinamide

Front 48

What are the food sources of Niacin?

Back 48

Fish and meats

Enriched cereals and grains

Legumes and seeds

Front 49

is Niacin effected by heat/acid/alkaline/light?

Back 49

Minimal loss with cooking and storage

Front 50

How is Niacin found in food primarily?

Back 50

Nicotinamide,

nicotinic acid,

NAD+,

NADP+

Front 51

What is the relationship between corn and Niacin?

Back 51

only 10% of niacin available in corn because of small peptides called niacinogens

Front 52

Other than food Niacin can also be found..

Back 52

Synthesized in the liver from tryptophan

Front 53

What % of tryptophan is metabolized to niacin?

Back 53

3%

Front 54

Where are free nicotinamide and nicotinic acid absorbed?

Back 54

small intestine

Front 55

Do nicotinamide and nicotinic acid need a carrier?

Back 55

Yes, saturable carrier

Front 56

In oxidation which dominates, NAD+ or NADH?

Back 56

NAD+

Front 57

In reduction which dominates, NADP+ or NADPH?

Back 57

NADPH

Front 58

What is the coenzyme role of Niacin?

Back 58

Dehydrogenases require NAD and NADP as coenzymes; tightly bound to apoenzyme.

They are H+ donors and acceptors

Front 59

NADH role

Back 59

formed from NAD, transfers its electrons picked up from metabolic intermediates to the ETC--> ATP

Front 60

NADPH role

Back 60

reducing agent in biosynthesis reactions (fatty acids, cholesterol, steroid hormones)

Front 61

NAD role... required for catabolism of....

Back 61

Vitamin B6

Front 62

Non redox role of Niacin...

Back 62

DNA function and calcium signaling

Front 63

The RDA for Niacin is based on..

Back 63

Human depletion and repletion studies

Studies with primary urinary metabolites

Front 64

What is the deficiency disease of Niacin?

Back 64

Pellegra, 4 D's

Front 65

Deficiency of Niacin from medications..

Back 65

Isonaizid (tuberculosis) inhibits niacin synthesis

Mercaptopurine (cancer)- inhibit NAD phosphorylase

Front 66

Does alcohol inhibit Niacin

Back 66

no

Front 67

Does Niacin have toxicity symptoms?

Back 67

Yes, large doses to treat hypercholesterolemia; niacin appears to block VLDL production (not a bad thing)

Pharmacological doses--> decreased cholesterol, triglycerides and LDL, increased HDL

Front 68

What is the UL of Niacin?

Back 68

35 mg

Front 69

How do you assess the nutriture of Niacin?

Back 69

Measurement of urinary metabolite levels

RBC NAD and NADP concentrations

Plasma 2-pyridine drops with low niacin intake; indicator

Front 70

What is the structure of pantothentic acid?

Back 70

B-alanine and pantoic acid joined by a peptide bond

part of coenzyme A

Front 71

What are the sources of pantothenic acid?

Back 71

Almost all plant and animal foods

Liver kidneys, yeast, egg yolk, broccli

Front 72

Is pantothenic acid destroyed be heat/light/acid/alkaline?

Back 72

Easily destroyed by heating and freezing

Destroyed by acidic and alkaline solutions

Front 73

Pantothenic acid is 85% of the time found as _______ in food

Back 73

Coenzyme A

Front 74

Where is Pantothenic Acid digested?

Back 74

GI tract where it is converted to free pantothenic acid

Front 75

Where is pantothenic acid absorbed?

Back 75

Jejunum

Front 76

Does pantothenic acid require a carrier?

High concentration vs low concentration

Back 76

Passive at high

Carrier dependent at low (Sodium Dependent Multivitamin Transporter)

Front 77

SMVT is shared with .... high doses of pantothenic acid....

Back 77

SMVT is shared with biotin and lipoic acid.

High doses of pantothenic acid interfere with biotin absorption in the intestine and the tissue levels.

Front 78

How is Pantothenic Acid transported?

Back 78

Red blood cells

Front 79

Where is pantothenic acid converted to Coenzyme A?

Back 79

inside of the cells

Front 80

Pantothenic acid functions as a component of....

Back 80

1. Coenzyme A

2. 4'-phosphopantatheine

Front 81

What is the structure of Coenzyme A?

Back 81

Phosphoantatheine and

adenosine-3',5'-biphosphate

Front 82

Coenzyme A forms _____ linkage with _______ of molecules; which ____________

Back 82

Coenzyme A forms a thioester linkage with carboxylic acid of molecules which activates them

Front 83

Coenzyme A can transfer the acyl groups (2-13 carbons) of....

Back 83

Acetic acid

Propionic acid

methylmalonic acid

succinic acid

Front 84

Coenzyme A is part of the __________ complex

Back 84

Pyruvate dehydrogenase

Introduces acetate for oxidation

Joins thiamin, riboflavin, and niacin in decarboxylation of pyruvate,

alpha ketogluturate (TCA) and

succinate (TCA)

Front 85

Coneyzme A transfers aceytl groups, which involves it in synthesis of...

Back 85

1. Cholesterol (Acetyl CoA+ Acetoacetyl Coa)

2. Fatty acids (Acetyl CoA + CO2)

3. Bile Salts

4. Ketone bodies

5. Steroid hormones

Front 86

Conenzyme A in acetylation of Nutrients: Sugars and Proteins

Back 86

A. Post transitional modifications of proteins

B. Choline --> acteylcholine

C. Acetylated sugars= cell surface molecules

Front 87

Coenzyme A in fatty acid synthesis via Acyl Carrier Protein (ACP)

Back 87

ACP is part of Fatty Acid Synthase Complex

SH group in 4'-phosphopantatheine of ACP bind and transfer acyl group (growing fatty acid)

Front 88

RDA for Pantothenic Acid

Back 88

None establish

Front 89

Deficiency of Pantothenic Acid

Back 89

Rare

Front 90

Assessment of nutriture

Back 90

Urinary pantothenic acid levels reflect dietary intake as excreted intact

Front 91

Raw egg whites block which vitamin?

Back 91

Biotin

Because of the substance avidin which tightly binds biotin inhibiting absorption

Front 92

What is the structure of Biotin?

Back 92

Ureido ring and thiophene ring with valeric acid side chain

Front 93

Biotin sources

Back 93

Colonic bacteria

Widespread in foods

Beef, soybean, liver, (cooked) egg yolk, cereal, and legumes

In food biotin covalently bound to protein or biotin linked to lysine (biocytin)

Front 94

What is biocytin

Back 94

Biotin linked to lysine

Front 95

Protein bound biotin is digested by... to....

Back 95

Digested by Proteases into biotin and biocytin

Front 96

Biocytin is digested by...

Back 96

Biotinidase in intestine and plasma

Front 97

Free biotin is absorbed...

Back 97

proximal small intesting (jejunum mostly)

Front 98

Free biotin needs a carrier?

Back 98

Yes, SMVT

Front 99

Sharing a transporter, panothenic acid and biotin creates a problem b/c

Back 99

they have to compete and could inhibit eachother

Front 100

Biotin's coenzyme role

Back 100

Metabolism of Carb, amino acids, and fatty acids

-bound to 4 carboxylases

Front 101

Attachment of biotin to a carboxylase requires...

Back 101

Holocarboxlase synthetase

Front 102

What are the four carboxylases Biotin attaches to

Back 102

1. Pyruvate carboxylase

2. Propionyl CoA Carboxylase (catabolism of odd carbon fatty acids)

3. Acetyl CoA Carboxylase

4. B-methylcortonyl CoA carboxylase

Front 103

Deficient in biotin-->

Back 103

urinary excretion of 3-hydroxyisovaleric acid, 3-HIA

Front 104

Biotin non coenzyme role

Back 104

Biotinylation of hisones--> unpacking of DNA

translation of some RNAs

Front 105

Assessment of Nutriture

Back 105

urinary biotin excretion

increased urinary 3-HIA excretion=deficiency