Amino Acids Flashcards

1
Q

amino acids

A

building blocks of proteins

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2
Q

basic chemical structure of amino acid

A

one amino group and one carboxyl functional group

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3
Q

alpha-carbon

A

N-terminal end and C-terminal end are bonded to this carbon.

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4
Q

peptide bond

A

linkage of the amino group of one amino acid to the carboxyl group of another amino acid

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5
Q

polypeptide

A

chain of amino acids linked by peptide bonds

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6
Q

protein

A

large polypeptide

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7
Q

size of proteins in serum

A

100-150 amino acids in length

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8
Q

essential amino acids- require dietary supplement

A

arginine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine

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9
Q

nonessential amino acids-not required dietary supplement

A

alanine, asparagine, aspartic acid, cysteine, glutamic acid, glutamine, glycine, proline, serine, and tyrosine

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10
Q

how much of total required daily energy do proteins provide

A

20%

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11
Q

what are the ketogenic amino acids

A

isoleucine, leucine, lysine, phenylalanine, tryptophan, tyrosine, and threonine

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12
Q

what are the glycogenic amino acids

A

alanine, arginine, aspartic acid, cysteine, glutamic acid, glutamine, glycine, phenylalanine, tryptophan, tyrosine, and threonine, isoleucine, valine, histidine, proline, methionine,

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13
Q

Role(s) of arginine

A

cell division, wound healing, stimulation of protein synthesis, immune function, release of hormones, and in conversion of ammonia to urea for excretion

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14
Q

Role(s) of histidine

A

grow and repair of body tissues, maintain myelin sheaths around nerve cells, precursor to histamine (immune response), manufacturing of red and white blood cells, protection from heavy metal toxicity, and source of carbon for synthesis of purine for DNA and RNA

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15
Q

Role(s) of isoleucine, leucine, and valine

A

branched chain amino-acids; promote healing of muscle tissue, skin, and bones; regulation of blood glucose levels; maintain energy levels; isoleucine in hemoglobin formation; leucine in infant growth; leucine and valine in nitrogen balance in adults

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16
Q

Role(s) of lysine

A

production of antibodies; lowering triglyceride levels; absorption and conservation of calcium; formation of collagen

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17
Q

Role(s) of methionine

A

initiation of translation of mRNA (first amino acid incorporated into N-terminal position of all amino acids); source of sulfur for metabolism and growth; breakdown of fats; detoxification of lead and other heavy metals; decrease muscle weakness and prevents brittle hair; reacts with ATP

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18
Q

Role(s) of phenylalanine

A

promotes alertness and vitality; elevates mood; decreases pain; aids in memory and learning; treatment for arthritis and depression; used by brain to produce norepinephrine; can interfere with serotonin production; direct precursor to tyrosine

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19
Q

Role(s) of threonine

A

formation of collagen, elastin, and tooth enamel

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20
Q

Role(s) of tryptophan

A

precursor for serotonin, melatonin, and niacin; natural relaxant; treatment of migrants, weight control, hyperactivity

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21
Q

Role(s) of alanine

A

product of DNA/dipeptide (anserine and carnosine) breakdown; transfers nitrogen from peripheral tissues to liver for processing and excretion; strengthens immune system through antibody production; reduces buildup of toxic substances when muscle protein is broken down quickly

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22
Q

Role(s) of asparagine

A

derived from aspartic acid and ATP; transport of nitrogen; requisite amino acid for nervous system; synthesis of ammonia; conversion of amino acids through amination or transamination

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23
Q

Role(s) of aspartic acid

A

aka aspartate; precursor or asparagine, arginine, lysine, methionine, threonine, isoleucine; metabolite in citric acid cycle and urea cycle; participation in gluconeogenesis

24
Q

Role(s) of cysteine

A

potentially toxic; absorbed as cystine; important structural and functional component of proteins

25
Q

Role(s) of glutamic acid

A

aka glutamate; precursor to glutamine; neurotransmitter; dysregulation leads to epileptic seizures; metabolism of fats and sugars; transport of potassium in to spinal fluid

26
Q

Role(s) of glutamine

A

precursor to proline; renal maintenance of acid-base balance; fuel for health digestive tract; basis of building blocks for synthesis or RNA and DNA; transport of ammonia to liver for metabolism

27
Q

Role(s) of glycine

A

synthesis of nucleic acids, bile acids, proteins, peptides, purines, ATP, porphyrins, hemoglobin, glutathione, creatine, bile salts, glucose, glycogen, and other amino acids; detoxification of compounds in liver; inhibitory neurotransmitter in CNS; metal complexing agent; retards muscle degeneration

28
Q

Role(s) of proline

A

precursor to hydroxyproline (needed for tendons, collagen, ligaments, and cardiac tissue); wound healing; works with vitamin C to promote healthy connective tissues

29
Q

Role(s) of serine

A

precursor to glycine; metabolism of lipids and fatty acids; synthesis of pyrimidines, purines, creatine, and porphyrins

30
Q

Role(s) of tyrosine

A

precursor to adrenal hormones (epinephrine, norepinephrine, and dopamine) and thyroid hormones (thyroxine); overall metabolism; function of adrenal glands, thyroid, and pituitary glands; mood elevator

31
Q

Selenocysteine

A

21st amino acid; not coded for in genetic code; coded for in stop codon UGA

32
Q

Pyrrolysine

A

22nd amino acid; coded for in stop codon UAG; not present in humans

33
Q

Aminoacidopathies

A

class of inherited errors of metabolism in which there is an enzyme defect that inhibits the body’s ability to metabolize certain amino acids

34
Q

Phenylketonuria

A

PKU; autosomal recessive; 1 in 15,000 births; classic PKU- absence of phenylalanine hydroxylase (PAH) activity increases phenylalanine >1200 micromol/L, which causes brain damage; causes urine to have musty odor; mild PKU is partial deficiency of PAH activity with phenylalanine between 600-1200 micromol/L;

35
Q

Normal phenylalanine in blood in infants

A

<120 micromol/liter; <2 mg/dL

36
Q

Symptoms of PKU

A

retarded mental development; microcephaly

37
Q

Hyperphenylalaninemia

A

phenylalanine elevation between 180-600 micromol/L without phenylketone elevation; deficiency in enzymes needed for regeneration and synthesis of BH4 (1-5% of all cases)

38
Q

PKU treatment

A

early detection, diet with low levels of phenylalanine (infant and mom)

39
Q

Tetrahydrobiopterin (BH4)

A

cofactor required for enzymatic hydroxylation of phenylalanine, tyrosine, and tryptophan; deficiency leads to elevation of phenylalanine and deficient production for neurotransmitters from tyrosine and tryptophan

40
Q

PKU detection

A

Guthrie test, HPLC, HPLC-MS/MS, microfluorometric assay of dried blood filter disks; GC-MS;

41
Q

Guthrie Test

A

semiquantitative, bacterial inhibition assay; sensitivity is 180 micromol/L (3mg/dL); blood is placed on agar dish that contains inhibitor of bacterial growth; if phenylalanine is present, inhibitor is overcome and bacteria grow

42
Q

Microfluorometric assay

A

quantitative; based on complex formed with phenylalanine and ninhydrin which causes fluorescence

43
Q

GC-MS

A

microwave assisted silylation; blood is rapidly derived with N,O, bis(trimethylsilyl)-trifluoroacetamine under microwave irradiation; analyzed by GCMS; confirmation method

44
Q

Tyrosinemia

A

autosomal recessive; metabolic disorder of tyrosine catabolism; elevated tyrosine in blood and elevated succinylacetone (toxic metabolite formed when tyrosine cannot be metabolized) by MS/MS; low protein diet required

45
Q

Alkaptornuria

A

autosomal recessive; 1 in 250,000 births; mutation in homogentisate oxidase (HGD) gene; required for metabolism of phenylalanine and tyrosine; elevated concentrations of homogentisic acid (HGA) in blood; symptoms present in 3rd decade of life; dark-blue/black pigmentation of of ears, nose, and tendons; small dark spots on sclera of eye; cause arthritis-like degeneration; urine mixed with air will result in brownish-black color due to oxidation of HGA; high dose Vitamin C

46
Q

Maple Syrup Urine Disease

A

autosomal recessive; 1 in 185,000 births; absence or reduced activity of branched-chain alpha-ketoacid decarboxylase (BCKD); inhibits metabolism of leucine, isoleucine, and valine; maple syrup or burnt sugar smell of urine, breath, and skin; symptoms in infants include lethargy, vomiting, lack of appetite, and failure to thrive within 1 week of birth; dietary restriction of proteins; leucine concentration of >4mg/dL

47
Q

Isovaleric Acidemia

A

1 in 250,000 births in US; mutation in isovaleryl-CoA dehydrogenase (IVD) gene; may be asymptomatic; distinctive odor of sweaty feet; may include failure to thrive, vomiting, lethargy; severe forms can result in permanent brain damage, nervous system damage, and death; protein restrictive diet and supplementation with glycine and carnitine

48
Q

Homocystinuria

A

autosomal recessive, 1 in 200,00 births; mutations in CBS, MTHFR, MTR, MTRR, and MMADHC genes; most common is mutation in CBS gene; Guthrie test; symptoms include nearsightedness, dislocation of the lens in the eye, mental retardation, osteoporosis; methionine >2mg/dL

49
Q

Citrullemia

A

urea cycle disorder; autosomal recessive

50
Q

Argininosuccinic aciduria

A

autosomal recessive; urea cycle disorder; 1 in 70,000 births; lack enzyme argininosuccinic acid lyase (ASL); nitrogen accumulates in blood (ammonia); clinical symptoms start within a few days of life with lethargy and unwillingness to eat; high caloric protein restrictive diet, arginine supplement

51
Q

Cystinuria

A

autosomal recessive; 1 in 10,000 births; mutation in SLC3A1 and SLC7A9 genes; elevated levels of cystine (also lysine, arginine, and ornithine); kidney stones, ureters, or bladder stones; other symptoms of hematuria, flank pain, urinary tract infections; increase of fluid uptake or penicillamine; diagnosed by cyanide nitroprusside which produces a red-purple color

52
Q

Type II citrullinemia

A

mutation in SLC25A13 gene, which encodes for production of the protein citrin (transports molecules inside cell that are used in production and breakdown of simple sugars, etc); cells are prevented from making citrin, inhibits urea cycle; elevation of ammonia and other toxic substances; confusion, restlessness, memory loss, personality changes, seizures, and coma; high caloric, protein restrictive diet; arginine supplement

53
Q

Methods of analysis-amino acids

A

blood drawn after 6-8 hours of fasting; collected in heparin tube and plasma removed immediately; hemolysis and contamination with white blood cells is unacceptable; deproteinization is performed within 30 min of sample collection and analysis performed immediately or sample stored below -20C; urine amino acids is performed on random specimen for screening and 24 hour urine for quantitative measurement

54
Q

Methods of analysis-amino acids

A

blood drawn after 6-8 hours of fasting; collected in heparin tube and plasma removed immediately; hemolysis and contamination with white blood cells is unacceptable; deproteinization is performed within 30 min of sample collection and analysis performed immediately or sample stored below -20C; urine amino acids is performed on random specimen for screening and 24 hour urine for quantitative measurement-preserved with thymol; TLC is method of choice- can be 1 or 2 dimensional- stained with ninhydrin to visualize; ion-exchange chromatography with fluorescence detection; LC-MS/MS

55
Q

normochromic normocytic anemia

A

type of anemia in which the circulating RBCs are the same size (normocytic) and have a normal red color (normochromic)