Amino Acids & Proteins Flashcards
are the building blocks of proteins.
Amino acids
TRUE/FALSE: Cellular growth, repair, and maintenance
are all dependent on amino acids.
TRUE
The amino group of one
amino acid can be linked with the carboxyl group of another amino acid
Peptide bond
Dietary proteins that completely digest dietary proteins into their constituent amino acids.
Pepsin & trypsin
PVTTIMHALL:
arginine, histidine, isoleucine, leucine, lysine,
methionine, phenylalanine, threonine, tryptophan, and valine.
Essential amino acids
proteins provide up to ___% of the total energy
required daily by the body.
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One important role is
the conversion of ammonia, which is highly toxic, into urea, which can be safely
excreted via the urinary system.
Arginine
needed to help grow and repair body tissues and to maintain the
myelin sheaths that protect nerve cells and is the direct precursor of histamine,
which is involved in immune response.
Histidine
are branched-chain amino acids that are
collectively referred to as the branched-chain amino acid group.
Isoleucine, leucine, and valine
plays an important role in hemoglobin formation,
isoleucine
necessary for optimal growth in infants.
leucine
also aid in
maintaining the nitrogen balance in adults.
Leucine and valine
used in treatments for
muscle, mental, and emotional problems such as insomnia and anxiety, as well as
liver and gallbladder disease.
Valine
It plays a role in the production of antibodies and lowering
triglyceride levels. helps in the absorption and conservation of
calcium and plays an important role in the formation of collagen
Lysine
is a source of sulfur, which is
required for normal metabolism and growth.
Methionine
uses an active transport channel to cross the blood–
brain barrier and is used by the brain to produce norepinephrine, a
neurotransmitter that transmits signals between nerve cells.
Phenylalanine
alcohol-containing amino acid that is an important component in
the formation of collagen, elastin (a connective tissue protein), and tooth enamel.
Threonine
metabolic precursor for serotonin, melatonin (a neurohormone), and niacin (a vitamin).
Tryptophan
one of the simplest amino acids and is a product of the breakdown of
DNA or the dipeptides, anserine and carnosine.
Alanine
plays a major role in
the transfer of nitrogen from peripheral tissues to the liver for processing and
excretion and strengthens the immune system through production of antibodies.
Alanine
one of the principal and most abundant amino acids involved in the transport of
nitrogen.
Asparagine
is the process by which an amine group is introduced into an organic
molecule,
Amination
is the transfer of an amino acid to an α-ketoacid.
transamination.
precursor for several
other amino acids. is a metabolite in the citric acid cycle and the urea
cycle. It also participates in the generation of glucose from nonsugar substrates,
Aspartic acid,
is an important structural and functional component of many proteins
and enzymes and has significant antioxidant properties.
Cysteine
serves as a neurotransmitter, and its
dysregulation has been linked to epileptic seizures. It is also important in the
metabolism of sugars and fats and aids in the transport of potassium into spinal
fluid.
Glutamic acid
the most abundant amino acid in the body and is synthesized from
glutamic acid.
Glutamine
synthesized from another nonessential amino acid, serine.
Glycine
involved in wound healing, especially that of cartilage, and in
the strengthening of joints, tendons, and cardiac tissue. It also works in tandem
with vitamin C to promote healthy connective tissues.
Proline
needed for the proper metabolism of lipids and fatty acids
and plays an important role in the body’s synthetic pathways for pyrimidines,
purines, creatine, and porphyrins.
Serine
precursor of the adrenal hormones epinephrine, norepinephrine, and dopamine
and thyroid hormones including thyroxine. It is important in overall metabolism
and aiding in function of the adrenal glands, thyroid, and pituitary glands.
Tyrosine
recognized as the 21st amino acid; encoded by a UGA codon; has a
specialized transfer RNA (tRNA).
Selenocysteine
the 22nd naturally occurring genetically encoded amino acid used
by some prokaryotes and single-celled microorganisms in enzymes that are part
of their methane-producing metabolism. This amino acid is not present in humans.
Pyrrolysine
are 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.
Aminoacidopathies
one of the most well-known aminoacidopathies and
was the first newborn screening test introduced in the early 1960s.
Phenylketonuria (PKU)
absence of activity of the enzyme phenylalanine hydroxylase (PAH) due to
mutations in the PAH gene.
PKU
In the newborn, the upper limit of normal
for phenylalanine concentration in the blood is
120 μmol/L (2 mg/dL).
In the
absence of PAH activity, phenylalanine concentrations are usually greater than
1,200 μmol/L
can also be the result of a deficiency in the enzymes
needed for regeneration and synthesis of tetrahydrobiopterin (BH4)
Hyperphenylalaninemia
cofactor required for the enzymatic hydroxylation of phenylalanine, tyrosine,
and tryptophan.
BH4
the first drug to help manage PKU.
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The drug helps reduce phenylalanine concentrations by increasing the activity of
the PAH enzyme.
sapropterin dihydrochloride (Kuvan®),
semiquantitative, bacterial inhibition assay for
phenylalanine based on the ability of phenylalanine to facilitate bacterial growth
in a culture medium despite the presence of a growth inhibitor.
Guthrie test
an agar gel plate containing _____ , a growth inhibitor,
is inoculated with Bacillus subtilis.
β-2-thienylalanine,
The Guthrie test is sensitive enough to detect serum
phenylalanine concentrations of
180 μmol/L (3 mg/dL).
The reference method for quantitative serum phenylalanine is _____;
however, _____ is now considered to be the gold standard for detecting a
variety of congenital diseases in newborns.
HPLC;MS/MS
Patients
with PKU generally demonstrate an _____ in phenylalanine concentrations
and a ______ in tyrosine concentrations.
increase;decrease
This
inborn metabolic disorder of tyrosine catabolism is characterized by the
excretion of tyrosine and its catabolites in urine or tyrosinuria.
Tyrosinemia
the most severe form occurring in about 1 in 100,000
births worldwide. This form of tyrosinemia is caused by a mutation in the FAH
gene, which codes for the enzyme fumarylacetoacetate hydrolase (FAH).
Type I tyrosinemia
caused by a mutation in the TAT gene, which leads to a
deficiency of the enzyme tyrosine aminotransferase (TAT).
Type II tyrosinemia
rare disorder with only a few cases having been
reported worldwide. It is caused by a mutation in the HPD gene that results in
deficiency of the enzyme 4-hydroxyphenylpyruvate dioxygenase (HPD).
Type III tyrosinemia
is a toxic metabolite that forms when tyrosine cannot be
metabolized through the appropriate enzymatic pathway.
Succinylacetone
The treatment for tyrosinemia is generally a low-protein
diet, but may also include medications such as
nitisinone (NTBC).
A mutation in the HGD
gene leads to a deficiency of the enzyme homogentisate oxidase (HGD), which
is required for proper metabolism of tyrosine and phenylalanine.
Alkaptonuria
HGA is
deposited in the cartilage of the ears, nose, and tendons of the extremities and
results in a dark blue-black pigmentation known as
ochronosis.
may be performed as a rapid screen for the presence
of HGA in urine.
ferric chloride test
Patients with alkaptonuria may be prescribed high-dose
Vitamin C
results from an absence or greatly reduced
activity of a complex of enzymes known as branched-chain α-ketoacid
decarboxylase (BCKD).
Maple syrup urine disease (MSUD)
modified Guthrie test (MSUD): An agar gel plate
containing _______, another growth inhibitor, is inoculated with Bacillus
subtilis.
4-azaleucine,
A leucine concentration greater than ____ is indicative of MSUD.
4 mg/dl
is an autosomal recessive disorder caused by mutation
of the IVD gene, which codes for isovaleryl-CoA dehydrogenase
Isovaleric acidemia (IVA)
Mutations in the CBS, MTHFR, MTR, MTRR, and MMADHC
can result in
homocystinuria.
This mutation results in a deficiency of the enzyme ______, which is necessary for metabolism of methionine.
cystathionine β-
synthase
Treatment includes dietary restriction of proteins to reduce concentrations of
methionine as well as high doses of
Vitamin B6
modified Guthrie test (Homocystinuria): In this form of the test, _________ is
utilized as the bacterial growth inhibitor and increased plasma methionine levels
will result in bacterial growth.
L-methionine sulfoximine
Citrullinemia belongs to a class of genetic diseases called
urea cycle disorders.
is the result of a mutation in the ASS1 gene. This gene
codes for synthesis of the enzyme argininosuccinic acid synthetase (ASS).
Type I citrullinemia
caused by a mutation in the SLC25A13 gene that
codes for production of the transport protein citrin.
Type II citrullinemia
helps transport
molecules inside the cell that are used in the production and breakdown of
simple sugars, production of proteins, and the urea cycle.
Citrin
another urea cycle amino acid disorder that
is inherited in an autosomal recessive pattern and is the result of a mutation in
the ASL gene.
Argininosuccinic aciduria (ASA)
is an inherited autosomal recessive disorder, occurring in
approximately 1 in 10,000 births worldwide, which is caused by mutations in the
SLC3A1 and SLC7A9 genes.
Cystinuria
characterized by inadequate reabsorption of cystine
during urine formation in the kidneys resulting in an elevated concentration of
cystine.
Cystinuria
forms a more soluble
complex with cystine, which prevents it from precipitating and forming stones.
Penicillamine
Cystinuria can be diagnosed by testing the urine for cystine using _______, which produces a red-purple color on reaction with sulfhydryl
groups.
cyanide
nitroprusside
Patients with cystinuria also excrete elevated concentrations of
lysine, arginine, ornithine
Blood samples for amino acid analysis should be drawn after at least _____hrs
of fasting to avoid the effect of absorbed amino acids originating from dietary
proteins.
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