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

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

1
Q

The only vitamin that is derived from glucose

A

Vitamin C

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2
Q

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

A

Gulonase

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3
Q

Humans cannot synthesize Vit. C because they lack this enzyme

A

L-gulonolactone oxidase

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4
Q

L-gulonolactone oxidase converts L-gulonolactone into _______

A

2-keto-L-gulonolactone

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5
Q

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

A

Hydroxylation reactions and tyrosine degradation

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6
Q

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

A

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

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7
Q

Vit. C in COLLAGEN SYNTHESIS

what AA residues are hydroxylated to form collagen

A

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

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8
Q

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

A

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

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9
Q

Inability to synthesize dopamine leads to what disease?

A

Parkinson’s disease

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10
Q

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

A

Phenylethanolamine-N-methyltransferase

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11
Q

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?

A

Cholesterol 7α-hydroxylase

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12
Q

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

A

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
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13
Q

Ascorbic acid in tyrosine degradation

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

A

Phenylalanine by phenylalanine hydroxylase; p-hydroxyphenylpyruvate via tyrosine aminotransferase

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14
Q

Ascorbic acid in tyrosine degradation

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

A

Homogentisate

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15
Q

Ascorbic acid in tyrosine degradation

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

A

1) fumarate (glucogenic)

2) Acetoacetate (ketogenic)

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16
Q

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

A

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

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17
Q

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

A

Thiamine

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18
Q

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 ______

A

Wernicke-korsakoff syndrome

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19
Q

True or false

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

A

True

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20
Q

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

A

Aldehyde group

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21
Q

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

A

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

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22
Q

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

A

isoalloxacin

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23
Q

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

A

Nicotinic acid (niacin)

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24
Q

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

A

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

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25
Q

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

A

Tryptophan

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26
Q

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

A

Diacylglycerol transferase-2

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27
Q

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

A

Pellagra

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28
Q

The genetic disorder where pellagra develops despite adequate tryptophan and niacin

A

Hartnup disease

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29
Q

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

A

Lysine

  • *forming biotinyl-lysine (biocytin)
  • *If biocytin is attached to an activated CO2, carboxy-biocytin is formed (active form of biotin)
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30
Q

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) ______

A

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

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31
Q

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

A

Folic acid

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32
Q

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?

A

C7 and N8

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33
Q

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

A

C6 and N5

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34
Q

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

A

N5 and N10

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35
Q

The most oxidized THF derivative

A

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

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36
Q

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:

A

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

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37
Q

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

A

Methionine – from homocysteine by methionine synthase

38
Q

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

A

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

39
Q

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

A

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
40
Q

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

A

10th reaction in the purine biosynthetic pathway

**C2 of the purine ring is acquired in this reaction catalyzed by formyl transferase

41
Q

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

A

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
42
Q

Competitive inhibitor of dihydrofolate reductase (3)

A

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

43
Q

Competitive inhibitor of thymidylate synthase

A

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

44
Q

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

A

Cobalamin (vit. B12)

45
Q

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

A

Cobalamin (Vit. B12)

46
Q

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

A

False – six coordination bonds

**4 from pyrrole rings, 5th from nitrogen of 5,6-dimethylbenzimidazole ribonucleotide, 6th from cyanide

47
Q

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

A

Pyridoxal phosphate (PLP)

48
Q

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

A

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

49
Q

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

A

Aminolevulinate synthase

50
Q

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

A

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
51
Q

Homocysteine to methionine is B12; Homocysteine to cysteine is ______

A

PLP

52
Q

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

A

PLP; ascorbic aicd

53
Q

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

A

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

54
Q

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

A

GABA

55
Q

PLP is attached to what AA residue of glycogen phosphorylase

A

Lysine

56
Q

Megaloblastic anemia; Folate deficiency: _____; PLP deficiency

A

Sideroblastic anemia

57
Q

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

A

Isoniazid

58
Q

Precursor of Vit. A or retinoids

A

Beta-carotene

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

59
Q

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

A

Retinyl phosphate

60
Q

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

A

Retinol and retinoic acid

61
Q

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

A

Retinol and retinoic acid

62
Q

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

A

11-cis-retinal

63
Q

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

A

Xeropthalmia

64
Q

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

A

Bitot’s spot

65
Q

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

A

7-dehydrocholesterol

66
Q

Ergocalciferol (D2) prepared by irradiating ergosterol from ______

A

yeast

67
Q

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

A

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

68
Q

What is the active form of Vit. D

A

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

69
Q

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

A

Parathyroid hormone (PTH)

70
Q

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

A

24,25-(OH)2D

71
Q

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

A

Vitamin E

72
Q

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

A

Vitamin E

73
Q 
Vit. E vitamers 
α-vitamers: 
β-vitamers: 
γ-vitamers:
delta-vitamers:
A

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

74
Q

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

A

α-Tocopherol

75
Q

Most potent scavenger of reactive nitrogen species (RNS)

A

γ-Tocopherol

76
Q

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

A

Phylloquinone (Vit. K1)

77
Q

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

A

Menaquinone (Vit. K2)

78
Q

Synthetic derivatives that can be metabolized to phylloquinone

A

Menadiol, menadione (Vit. K3) and menadiolo acetate

79
Q

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

A

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
80
Q

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 _________

A

O2 and CO2 transport; oxidative phosphorylation

81
Q

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

A

Iodine

82
Q

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

A

Metallothionein

83
Q

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

A

Gustin

84
Q

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)?

A

Ferroxidase

85
Q

Drug-nutrient interaction
Drug: Alcohol
Potential Nutrient Deficiencies:

A

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

86
Q

Drug-nutrient interaction
Drug: Anticonvulsants
Potential Nutrient Deficiencies:

A

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

87
Q

Drug-nutrient interaction
Drug: Cholestyramine
Potential Nutrient Deficiencies:

A

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

88
Q

Drug-nutrient interaction
Drug: Corticosteroids
Potential Nutrient Deficiencies:

A

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

89
Q

Drug-nutrient interaction
Drug: Diuretics
Potential Nutrient Deficiencies:

A

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

90
Q

Drug-nutrient interaction
Drug: Isoniazid
Potential Nutrient Deficiencies:

A

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

91
Q

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

A

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

Biochemistry (books and trans) (6 decks)

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