Biochemical role of vitamins and minerals (trans 2-3, devlin Ch. 28)

Question 1

The only vitamin that is derived from glucose

Answer 1

Vitamin C

Question 2

What enzyme in the Uronic Acid pathway acts on L-gulonic acid to form L-gulonolactone?

Answer 2

Gulonase

Question 3

Humans cannot synthesize Vit. C because they lack this enzyme

Answer 3

L-gulonolactone oxidase

Question 4

L-gulonolactone oxidase converts L-gulonolactone into _______

Answer 4

2-keto-L-gulonolactone

Question 5

As a COENZYME, Vit. C is involved in what reactions? (2)

Answer 5

Hydroxylation reactions and tyrosine degradation

Question 6

As a REDUCING AGENT, Vit C facilitates the absorption of ______

Answer 6

Intestinal iron absorption – by converting Fe3+ (ferric) to Fe2+ (ferrous), which is more absorbable in the body

Question 7

Vit. C in COLLAGEN SYNTHESIS

what AA residues are hydroxylated to form collagen

Answer 7

Proline and lysine – catalyzed by prolyl hydroxylase and lysyl hydroxylase, respectively

Question 8

In catecholamine formation, Ascorbic acid participate in what reaction as a coenzyme to yield what product?

Answer 8

Hydroxylation of dopamine with the enzyme DOPAMINE β-HYDROXYLASE, to yield NOREPINEPHRINE

Question 9

Inability to synthesize dopamine leads to what disease?

Answer 9

Parkinson’s disease

Question 10

Norepinephrine undergoes methylation to form epinephrine. The source of the methyl group is from S-Adenosyl methionine (SAM). This reaction is catalyzed by _____

Answer 10

Phenylethanolamine-N-methyltransferase

Question 11

7α-hydroxycholesterol undergoes a series of steps for form the primary bile acids cholic and chenocholic acid. In the formation of 7α-hydroxycholesterol, cholesterol is acted upon by what enzyme where ascorbic acid is a cofactor?

Answer 11

Cholesterol 7α-hydroxylase

Question 12

Lysine hydroxylation is to collagen formation; Lysine methylation is to ______

Answer 12

L-carnitine synthesis

• *Lysine residues in protein undergo methylation three times, with SAM as the methyl group donor, to form ε-N-trimethyllisine
• *ε-N-trimethyllisine undergoes four more steps to produce L-carnitine, with these steps requiring Vitamin C as a cofactor

Question 13

Ascorbic acid in tyrosine degradation

_______ is hydroxylated to Tyrosine. And Tyrosine is deaminated to _____

Answer 13

Phenylalanine by phenylalanine hydroxylase; p-hydroxyphenylpyruvate via tyrosine aminotransferase

Question 14

Ascorbic acid in tyrosine degradation

P-hydroxyphenylpyruvate is converted to ______ via p-hydroxyphenylpyruvate dioxygenase, with Vit. C as a cofactor

Answer 14

Homogentisate

Question 15

Ascorbic acid in tyrosine degradation

Homogentisate undergoes a series of reactions to form a compound with either a 1) _____or 2) ______ backbone.

Answer 15

1) fumarate (glucogenic)

2) Acetoacetate (ketogenic)

Question 16

Deficiency of p-hydroxyphenyl-pyruvate dioxygenase results to ________.

Answer 16

Neonatal tyrosinemia
** treated with dietary protein restriction and ascorbate supplementation (since enzyme requires ascorbate for its activity).

Question 17

Consists of a thiazole ring joined to a substituted pyrimidine by a methylene bridge

Answer 17

Thiamine

Question 18

Symptoms of moderately severe thiamine deficiency include mental confusion, ataxia (unsteady gait while walking and general inability to achieve fine control of motor functions), and ophthalmoplegia (loss of eye coordination). This set of symptoms is usually referred to as ______

Answer 18

Wernicke-korsakoff syndrome

Question 19

True or false

Beri-beri is found primarily in populations relying exclusively on polished rice for food

Answer 19

True

Question 20

The reactive carbon in the thiazole ring of the thiamine carries what group?

Answer 20

Aldehyde group

Question 21

What various dehydrogenases in the TCA require TPP as a coenzyme?
Formation of acetyl CoA from pyruvate
Formation of α-ketoglutarate from isocitrate
Formation of succinyl CoA from α-ketoglutarate

Answer 21

Formation of acetyl CoA from pyruvate: pyruvate dehydrogenase
Formation of α-ketoglutarate from isocitrate: isocitrate dehydrogenase
Formation of succinyl CoA from α-ketoglutarate: α-ketoglutarate dehydrogenase

Question 22

Riboflavin consists of what heterocyclic ring that is connected through N10 to the alcohol ribitol?

Answer 22

isoalloxacin

Question 23

It has a pyridine containing positively charged nitrogen at position 1 in the ring

Answer 23

Nicotinic acid (niacin)

Question 24

Dinucleotides in NAD are joined together by what linkage between 1st nucleotide and phosphate of the 2nd nucleotide, and its carbon in the nicotinamide?

Answer 24

Anhydride linkage – this makes it possible to accept negative hydride ion

Question 25

Niacin can be synthesized from what AA with the presence of vitamins B2, B6 and Fe2+?

Answer 25

Tryptophan

Question 26

Niacin lowers TAG and LDL cholesterol because of noncompetitive inhibition to what enzyme in the liver?

Answer 26

Diacylglycerol transferase-2

Question 27

This is a condition that result from niacin deficiency which involves the skin, GIT and CNS and characterized by the 3 D’s symptoms

Answer 27

Pellagra

Question 28

The genetic disorder where pellagra develops despite adequate tryptophan and niacin

Answer 28

Hartnup disease

Question 29

Biotin is covalently bound to the ε-amino groups of what amino acid residues of biotin-dependent carboxylases?

Answer 29

Lysine * *forming biotinyl-lysine (biocytin) * *If biocytin is attached to an activated CO2, carboxy-biocytin is formed (active form of biotin)

Question 30

Leucine, one of the essential amino acids, is degraded into either acetoacetate or acetyl CoA via several intermediates utilizing biotin as a source of CO2 in the carboxylation of 1) _______ to 2) _______, via 3) ______

Answer 30

1) β-methylcrotonyl CoA 2) β-methylglutaconyl CoA 3) ß-methynylcrotonyl CoA carboxylase

Question 31

Pteridine ring which is composed of fused pyrimidine and pyrazine ring, PABA and several glutamate

Answer 31

Folic acid

Question 32

Folic acid is reduced to dihydrofolate catalyzed by the enzyme dihyrdofolate reductase with NADPH as the reductant. Where is the 2 H+ located in the pteridine ring?

Answer 32

C7 and N8

Question 33

Hydrofolate will undergo further reduction to form Tetrahydrofolate, adding another two molecules of H+ atom in what location of the pteridine ring

Answer 33

C6 and N5

Question 34

What is the location of the one-carbon unit carried by tetrahydrofolate (THF or FH4)?

Answer 34

N5 and N10

Question 35

The most oxidized THF derivative

Answer 35

N10-Formyl Tetrahydrofolate | ** In the presence of formic acid or formate and ATP it donates carbon atom to N10 of THF, forming a formyl group at N10

Question 36

Main sources of one-carbon group Condenses with THF to produce N5, N10 – Methylene THF: Condenses with THF to produce N5FormiminoTHF, and with the removal of amino group forms N5, N10 – Methenyl THF: Converted to formate or formic acid and condenses with THF to form N10formyl THF:

Answer 36

Condenses with THF to produce N5, N10 – Methylene THF: Serine and Glycine Condenses with THF to produce N5FormiminoTHF, and with the removal of amino group forms N5, N10 – Methenyl THF: Histidine Converted to formate or formic acid and condenses with THF to form N10formyl THF: Tryptophan

Question 37

N5-MethylTetrahydrofolate is converted to THF in the presence of B12 to synthesize _______

Answer 37

Methionine – from homocysteine by methionine synthase

Question 38

N5, N10 – Methylene THF as the donor of one carbon atom group and PLP as a cofactor is converted to THF to synthesize _____

Answer 38

Glycine to serine (reversible) – by the enzyme Serine hydroxymethyltransferase

Question 39

In purine nucleotide synthesis, N5, N10 – Methenyl THF is the donor of one carbon atom in what reaction?

Answer 39

4th reaction in the purine biosynthetic pathway * *wherein glycinamide ribosyl-5-phosphate (GAR, IV) is converted to formylglycinamide ribosyl-5-phosphate (FGAR, V) * *C8 of the purine ring is acquired in this reaction catalyzed by formyl transferase

Question 40

In purine nucleotide synthesis, N10-Formyl THF is the donor of one carbon atom in what reaction?

Answer 40

10th reaction in the purine biosynthetic pathway | **C2 of the purine ring is acquired in this reaction catalyzed by formyl transferase

Question 41

Deoxyuridine monophosphate (dUMP) is converted to Deoxythymidine monophosphate (dTMP) by the enzyme Thymidylate synthase with what THF derivative as the carbon donor?

Answer 41

N5, N10 – Methylene THF * *the methylene group is transferred to C5 of dUMP * *dTMP is a precursor in the synthesis of DNA and RNA, including cancer cells

Question 42

Competitive inhibitor of dihydrofolate reductase (3)

Answer 42

1) Methotrexate (MTX – 4-amino-10-methylfolate) 2) Aminopterin 3) Trimethoprim (antibiotic for urinary infections – inhibitor of dihydrofolate reductase in some bacteria)

Question 43

Competitive inhibitor of thymidylate synthase

Answer 43

Deoxyflouridine monophosphate (dFUMP) – from 5-fluorouracil (5-FU)

Question 44

Needed for the isomerization (rearrangement) of L-methylmalonyl CoA into succinyl CoA via methylmalonyl CoA mutase

Answer 44

Cobalamin (vit. B12)

Question 45

Contains corrin ring system wherein 2 of the 4 pyrrole rings are linked directly

Answer 45

Cobalamin (Vit. B12)

Question 46

True or False In Cobalamin, Cobalt (Co2+), a trace element, is found at the center of the corrin ring which is held by four coordination bonds

Answer 46

False – six coordination bonds | **4 from pyrrole rings, 5th from nitrogen of 5,6-dimethylbenzimidazole ribonucleotide, 6th from cyanide

Question 47

Its functional group is the reactive aldehyde that forms a covalent intermediate with amino groups of amino acids

Answer 47

Pyridoxal phosphate (PLP)

Question 48

This reaction is catalyzed by alanine aminotransferase, in the presence of PLP as a coenzyme

Answer 48

Alanine loses its amino group to alpha-ketoglutarate forming pyruvate and glutamate

Question 49

PLP is a coenzyme in the synthesis of δ-aminolevulinic aicd from glycine and succinyl CoA catalyzed by what enzyme

Answer 49

Aminolevulinate synthase

Question 50

True or False Pyridoxal phosphate as a coenzyme in amino acid metabolism – decarboxylation, serine is decarboxylated to pyruvate via serine decarboxylase

Answer 50

False * *In decarboxylation reaction of amino acid, PLP participates in the decarboxylation of HISTIDINE to HISTAMINE with the enzyme Histidine decarboxylase * *In deamination reaction of amino acid, PLP participates in the deamination of serine to pyruvate via deaminase

Question 51

Homocysteine to methionine is B12; Homocysteine to cysteine is ______

Answer 51

PLP

Question 52

DOPA carboxlase is to ______; dopamine beta-hydroxylase is to ________

Answer 52

PLP; ascorbic aicd

Question 53

PLP is a cofactor of tryptophan decarboxylase is involve in what reaction

Answer 53

Serotonin production **when acetyl-CoA bonds with serotonin to produce n-acetyl serotonin, it is acted upon by hydroxyindole-O-methyl transferase to produce melatonin

Question 54

Glutamate is converted to what product by decarboxylation reaction where PLP is a coenzyme

Answer 54

GABA

Question 55

PLP is attached to what AA residue of glycogen phosphorylase

Answer 55

Lysine

Question 56

Megaloblastic anemia; Folate deficiency: _____; PLP deficiency

Answer 56

Sideroblastic anemia

Question 57

What anti TB drug has almost the same structure as Pyridoxine and thus can induce B6 deficiency by forming inactive derivative with PLP

Answer 57

Isoniazid

Question 58

Precursor of Vit. A or retinoids

Answer 58

Beta-carotene | ** cleaved at the center via Beta-carotene dioxygenase (oxidation reaction) = 2 molecules of retinol

Question 59

This derivative of retinol apears to serve as a glycosyl donor in the synthesis of some glycoproteins and mucopolysaccharides in much the same manner as dolichol phosphate

Answer 59

Retinyl phosphate

Question 60

These vitamin A derivatives can be considered to act like steroid hormones in regulating cell growth and differentiation

Answer 60

Retinol and retinoic acid

Question 61

Vitamin A derivative required for the synthesis of iron transport protein transferring

Answer 61

Retinol and retinoic acid

Question 62

In rods and cones of retina in the absence of light, what isomer of retinal exists?

Answer 62

11-cis-retinal

Question 63

Pathological dryness of conjunctiva (xerosis conjunctiva) and cornea (xerosis cornea) which may lead to corneal ulceration & blindness due to excessive keratinization of epithelial cells

Answer 63

Xeropthalmia

Question 64

Dry, silver- gray plaques on the bulbar conjunctiva due to keratinization of epithelium

Answer 64

Bitot’s spot

Question 65

Cholecalciferol (D3) is produced in the skin by UV irradiation of _____

Answer 65

7-dehydrocholesterol

Question 66

Ergocalciferol (D2) prepared by irradiating ergosterol from ______

Answer 66

yeast

Question 67

What is the predominant form of Vit. D (major storage form)

Answer 67

25-hydroxycholecalciferol or calcidiol ** 1st hydroxylation reaction in the liver – involves ring opening of cholecalciferol structure and hydroxylation at 25 position in the presence of cytochrome P450, O2 and NADPH as cofactors, catalyzed by 25-hydroxylase

Question 68

What is the active form of Vit. D

Answer 68

1,25-dihydroxy- cholecalciferol or calcitriol ** 2nd hydroxylation reaction in the kidney – 25- hydroxycholecalciferol is brought to the kidneys via the blood and undergoes further hydroxylation at position 1 via 25-hydroxycholecalciferol 1- hydroxylase in the presence of cytochrome P450, O2 and NADPH

Question 69

What hormone plays a major role in regulation the activation of vitamin D?

Answer 69

Parathyroid hormone (PTH)

Question 70

High parathyroid hormone; 1,25-(OH)2D: Low parathyroid hormone; ______

Answer 70

24,25-(OH)2D

Question 71

This vitamin plays a role in cellular respiration either by stabilizing coenzyme Q or by helping transfer electrons to coenzyme Q

Answer 71

Vitamin E

Question 72

It contains a substitute aromatic ring and a long isoprenoid side chain

Answer 72

Vitamin E

Question 73

``` Vit. E vitamers α-vitamers: β-vitamers: γ-vitamers: delta-vitamers: ```

Answer 73

α-vitamers: R = CH3; R1 = CH3 β-vitamers: R = CH3; R1 = H γ-vitamers: R = H; R1 = CH3 delta-vitamers: R = H; R1 = H

Question 74

Most potent scavenger of reactive O2 species. (ROS); complements antioxidant property of glutathione

Answer 74

α-Tocopherol

Question 75

Most potent scavenger of reactive nitrogen species (RNS)

Answer 75

γ-Tocopherol

Question 76

Present in green vegetables, the normal dietary source of vitamin k

Answer 76

Phylloquinone (Vit. K1)

Question 77

Type of vitamin k that are synthesized by intestinal bacteria, with differing lengths of side chain

Answer 77

Menaquinone (Vit. K2)

Question 78

Synthetic derivatives that can be metabolized to phylloquinone

Answer 78

Menadiol, menadione (Vit. K3) and menadiolo acetate

Question 79

Vitamin K promotes the carboxylation of one or more glutamic acid residues to y-carboxyglutamic acid of what clotting factors?

Answer 79

Clotting factors II (protrombin), VII, IX, and X * * y-carboxyglutamic acid are good chelators and allow prothrombin to bind calcium * *the prothrombin-Ca++ complex in turn binds to phopholipid membrane where proteolytic conversion to thrombin can occur in vivo

Question 80

Iron plays a number of important roles in the body. As a component of hemoglobin and myoglobin, it is required for _______. As a component of cytochromes and nonheme iron proteins, it is required for _________

Answer 80

O2 and CO2 transport; oxidative phosphorylation

Question 81

Absorbed and transported to the thyroid gland, where it is stored and used for synthesis of the thyroid hormones triiodothyronine and thyroxine

Answer 81

Iodine

Question 82

Zinc absorption appears to be proportional to _____ in intestinal mucosa cells

Answer 82

Metallothionein

Question 83

Zinc is also present in what salivary polypeptide that appears to be necessary for normal development of taste buds?

Answer 83

Gustin

Question 84

What copper-containing enzyme is necessary for conversion of iron from the Fe2+ state (in which form it is absorbed) to the Fe3+ state (in which form it can bind to the plasma protein transferrin)?

Answer 84

Ferroxidase

Question 85

Drug-nutrient interaction Drug: Alcohol Potential Nutrient Deficiencies:

Answer 85

Drug-nutrient interaction Drug: Alcohol Potential Nutrient Deficiencies: Thiamine, Folic acid and Vitamin B6

Question 86

Drug-nutrient interaction Drug: Anticonvulsants Potential Nutrient Deficiencies:

Answer 86

Drug-nutrient interaction Drug: Anticonvulsants Potential Nutrient Deficiencies: Vitamin D, Folic acid snd Vitamin K

Question 87

Drug-nutrient interaction Drug: Cholestyramine Potential Nutrient Deficiencies:

Answer 87

Drug-nutrient interaction Drug: Cholestyramine Potential Nutrient Deficiencies: Fat-soluble vitamins, Iron

Question 88

Drug-nutrient interaction Drug: Corticosteroids Potential Nutrient Deficiencies:

Answer 88

Drug-nutrient interaction Drug: Corticosteroids Potential Nutrient Deficiencies: Vitamin D, calcium, Zinc and Potassium

Question 89

Drug-nutrient interaction Drug: Diuretics Potential Nutrient Deficiencies:

Answer 89

Drug-nutrient interaction Drug: Diuretics Potential Nutrient Deficiencies: Potassium and Zinc

Question 90

Drug-nutrient interaction Drug: Isoniazid Potential Nutrient Deficiencies:

Answer 90

Drug-nutrient interaction Drug: Isoniazid Potential Nutrient Deficiencies: Vitamin B6

Question 91

Drug-nutrient interaction Drug: Oral contraceptives and estrogens Potential Nutrient Deficiencies:

Answer 91

Drug-nutrient interaction Drug: Oral contraceptives and estrogens Potential Nutrient Deficiencies: Vitamin B6, Folic acid and B12