AMINO ACIDS AND PROTEINS Flashcards
building blocks of proteins
amino acids
amino acids provide ____ of the total body energy requirement
12-20%
amino acids contain at least one ____ and ____ group
N-terminal end amino group; C-terminal end carboxylic group
what links amino acids together to form a polypetide
peptide bonds
what differentiates amino acids from one another
chemical composition of their R group
these cannot be synthesized by the body and must be obtained from the diet
essential amino acids
example of proteolytic enzymes that cleave dietary proteins into constituent amino acids
pepsin and trpysin
give 10 essential amino acids
histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, valine, arginine
it is 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
what is the enzyme deficient in phenylketonuria
phenylalanine hyroxylase (converts phenyalanine to tyrosine)
odor of urine in phenylketonuria
mousy
deficient enzymes in tyrosinemia
type I: fumarylacetoacetate hydrolase
type 2: tyrosine aminotransferase
type 3: 4-hydroxyphenylpyruvate dioxygenase
deficient enzymes in alkaptonuria
homogentisate oxidase
deficient enzymes in MSUD
branched-a ketoacid decarboxylase
deficient enzymes in isovaleric acidemia
isovaleryl coA- dehydrogenase
deficient enzyme in homocystinuria
cystathione B-synthase
deficient enzyme in cystinuria
none; it only has a defect in amino acid transport
what AA accumulate in MSUD
leucine, isoleucine, valine
what AA are defectively reabsorbed in cystinuria
lysine, ornithine, cysteine, arginine
Why are proteins amhoteric/ampholytic
because they can be acidic or alkaline depending on the body ph
at ph <3.5 proteins behave as
cation
at ph >3.5 proteins behave as
anion
what is isoelectric point
it is the ph at which proteins do not have a net charge (zwitterions)
what comprises proteins
carbon, hydrogen, oxygen, nitrogen, sulfur
what percentage of nitrogen do proteins have
16%
Analogy:
Intracellular proteins: ____
_____: ribosomes attached in the rer
free ribosomes
extracellular
which organ synthesizes proteins
liver
severe or chronic liver diseases cause a ___ in plasma protein concentration leading to ____
decrease; hypoproteinemia
proteins comprises ___ of the cell’s dry weight
50-70%
what differentiates proteins from lipids and carbohydrates in terms of storage
proteins do not have a designated storage depot in the body
negative nitrogen balance: catabolism ___ anabolism
positive: anabolism ___catabolism
> ; >
conditions where a negative nitrogen balance is seen
excessive tissue destruction such as burns, wasting disease, high fever, starvation
conditions where a positive nitrogen balance is seen
growth, pregnancy, repair processes
protein is a transport carrier for susbtances such as
bilirubin, heme, hemoglobin, iron, copper, drugs, hormones
it is the most flexible transport protein
albumin
it is the consequence of low osmotic pressure
edema
how many g of albumin is excreted in the urine per day when there is nephrotic syndrome
3-4 grams
it is the linear sequence of amino acids and determines the identity of the protein
primary structure
it involves the winding of the polypeptide chain
secondary structure
what are the common secondary structures
alpha-helix,beta pleated, bend conformation
it is the actual 3D conformation of the protein
tertiary structure
what protein structure is affected by denaturation
secondary, tertiary and quaternary
factors causing denaturation
heat, strong acid/alkali, enzymatic reactions, exposure to urea and other subs, exposure to UV
transport proteins: (3)
apotrasferrin, apoceruloplasmin, albumin
structural proteins (3)
collagen, elastin, keratin
what are simple proteins
contain a peptide chain which on hydrolysis yields only amino acids
example of fibrous proteins
fibrinogen, troponin, collagen
example of globular proteins
globin enzyme, peptide hormone, albumin
what are conjugated proteins
proteins composed of an apoprotein and a non protein moiety (prosthetic group)
give examples of the ff: metalloproteins lipoproteins glycoprotein mucoprotein nucleoprotein
metalloproteins: ferritin, flavoprotein, hemoglobin, ceruloplasmin
lipoprotein: vldl ldl hdl chylomicrons
glycoprotein: haptoglobin, and alpha-1 antitrypsin
mucoprotein: mucin
nucleoprotein: chromatin
these are the most frequently analyzed of all the proteins
plasma proteins
plasma proteins are divided into:
albumin and globulin
the blood panel for plasma protein analysis consists of
total protein
albumin
globulin
A:G ratio
this is a sensitive marker of nutritional status
pre albumin
pre albumin is the transport protein for:
T4 and retinol
why is pre albumin used to confirm is sample is really CSF
pre albumin crosses the CSF more easily compared to other proteins
albumin comprises __% of the plasma protein mass
50%
albumin transports:
bilirubin, fatty acids, calcium, magnesium, drugs, Salicyclic acid, dyes
albumin is responsbile for 80% of _____ of the ___
colloid osmotic pressure; intravascular fluid
is albumin a neg or pos APR
neg
lowest plasma levels of albumin is seen in
nephrotic syndrome
conditions where hypoalbuminemia is seen
malnutrition and malabsorption
liver dx
protein losing enteropathy or GI los
renal dx (nephrotic syndrome or glomerulonephritis)
acute dx states
mutation resulting from an autosomal recessive trait causing analbuminemia and bisalbuminemia
hemodilution, increased capillary permeability, and sepsis
hyperalbuminemia is seen in what conditions
dehydration
excessive albumin infusion
globulins are group of proteins consisting of
alpha 1, alpha 2, beta, and gamma fractions
what does A1 antitrypsin inhibit?
it inhibits neutrophil elastase which are released by WBC to fight infection
it is the major inhibitor of protease activity (preventing self destruction of tissues)
A1 antitrypsin
A1 antitrypsin is deficient in conditions such as
emphysematous pulmonary disease and juvenile hepatic cirrhosis
where is A1 fetoprotein synthesized
it is synthesized initially in the fetal yolk sac and then by the fetal parenchymal cells of the liver
when does the concentration of AFP peaks in the fetus
13th week of gestation
Physiologic increase of AFP: ___
Pathologic increase of AFP: ____
Pathologic decrease of AFP: _____
pregnant women with twins
neural tube defects (spina bifida and anencephaly), low folate
down syndrome and trisomy 18
QUAD marker
high HCG and inhibin A and low maternal serum AFP and urinary estriol
AFP is used as a tumor marker for ___
hepatic and gonadal cancer
A1 - acid glycoprotein (orosomucoid) contains the highest percentage of __ and ___
CHO and sialic acid
why is orosomucoid negatively charged even in acid solution
because it has a low isoelectric point 2.7 and due to high sialic acid content
orosomucoid provides a useful diagnostic tool for ___
neonates with bacterial infecitons
A1 acid glycoprotein has high affinity to ___ and binds ___
progesterone ; quinidine
A1- antichymotrypsin binds and inactivates ____
prostate specific antigen
A1- antichymotrypsin is an integral component of ___ found in Alzheimer’s dx
amyloid plaques
what does A1-antichymotrypsin inhibits
serine proteases like; cathepsin C, pancreatic elastase, chymase and chymotrypsin
it transports lipids and is the major component of hdl
A1- lipoprotein
this inhibits serine proteases
inter-alpha-trypsin inhibitor
function of group specific globulin
it transports vitamin D and binds actin
what are the A1 globulins
haptoglobin, a2-macrogloblulin, apoceruloplasmin
what is the function of haptoglobin
it binds the free hemoglobin by its alpha chain
haptoglobin is decreased in ___
intravascular hemolysis and hemoglobinuria
it is the largest major nonimmunoglobulin protein in plasma
a2- macroglobulin
where is a2- macroglobulin primarily found
intravascular space
in what condition does the concentration of a2- macroglobulin increases 10x
nephrosis
it is a copper binding alpha-2 glycoprotein that has enzymatic activities
apoceruloplasmin
where is apoceruloplasmin synthesized
liver (6-8 atoms attached forming ceruloplasmin)
what color does it impart to proteins
blue
apoceruloplasmin is decreased in what conditions
Wilson’s dx, menke’s kinky hair syndrome
copper deposits in the cornea
kayser fleischer rings
what are the B- globulins
Pre-b lipoprotein; transferrin; hemopexin; B-lipoprotein; B2- microglobulin; complement, CRP
Analogy:
Pre-b lipoprotein: ___
______: LDL
VLDL trigylcerides
b-lipoprotein
Transferrin comprises ___ of the beta globulin fraciton
90%
how many molecules of ferric ion does transferrin transport
2
level of transferrin in IDA
normal or increased (paraprotein)
what does hemopexin do
it binds the free heme and evaluates early hemolysis
B2-microglobulin is a light chain component of MHC class __ which are found in ___
II; nucleated cells
B2 microglobulin is recognized by ___
Cd8 or cytotoxic cells
functions of complement
cell lysis; opsonization; anaphylaxis; inflammation
which complement is present in high concentration in the plasma
c3
CRP is named after its ability to bind with the ___ of ___
C-polysaccaride; pneumococci
it is used as an early warning test to persons at risk of coronary artery disease
hsCRP
it is the most abundant of the coagulation factors
fibrinogen (factor 1`)
effect of high levels of fibrinogen in the plasma
it may elevate the ESR which favors rouleaux formation which sediments faster
fibrinogen is found between __ and ___ globulin
beta and gamma
antibodies in the neonatal serum are of ____ origin
maternal
myoglobin is a primary-oxygen carrying protein found in ___ and ___
striated skeletal muscle and cardiac muscle
give the onset, peak, and normalize of myoglobin
2-3 hrs; 8-12 hrs; 18-30 hrs
myoglobin is not cardiospecific because it is also elevated in ___ and ___
progressive muscular dystrophy and crushing injury
which troponins are considered as gold standard tess for acute coronary syndrome
T and I
which troponin is present in both cardiac and skeletal muscle; binds calcium to regulate muscle contraction
C
Analogy:
Troponin T: ____ ( onset: ___ peaks: ____ normalize: ___
____: myocardium
heart muscle (3-4; 10-24; 7 days Troponin I
it is a potent vasodilator that promotes natriuresis
natriuretic peptide
fibronectin plays a role in ___, ___, ___, ____
cell adhesion, tissue differentiation, growth and wound healing
B-trace protein is established as an accurate marker of ___
CSF leakage
CTXs is a biochemical marker of ____
bone resorption
Cystatin C is an endogenous marker of ___
GFR
test used for differential diagnosis of Alzheimers dx
Amyloid b-42 and Tau test
test indicating increased likelihood of alzheimer’s dx
low AB42 and high Tau test
microalbuminuria is increased in ___, ____,___,___
fever, infection, hypertension, diabetic nephropathy
it is the presence in CSF of two or more IgG bands in the gamma region
CSF oligoclonal banding
other disorders with two or more bands in the CSF: (4)
neoplastic d/o. neurosyphilis, encephalitis, and guillan barre syndrome
supporting medium and stain for CSF oligoclonal banding
agarose gel and coomasie brilliant blue stain
