PROTEIN Flashcards
aralllll fles
sequence of the AA in the polypeptide chain (linear)
Primary Structure
determines the overall shape of the protein
Primary Structure
Analytical processes of primary structure
- chromatography
- electrophoresis
- dye binding
- light absorbance
Analytical processes: chromatography, electrophoresis, dye binding and light absorbance depends on this sequence
Primary sequence
conformation of the segments of the polypeptide chain
Secondary structure
secondary structure maintained by:
Hydrogen Bond
Important for the strength and flexibility of proteins
secondary structure
arises from the interaction among the different segments of a polypeptide chain
secondary structure
3 structures of secondary structure
- Alpha-Helix
- Beta-Pleated sheets
- Random coils
Chain forms a regular helix; coil
resembling a spring
Alpha-Helix
In fully extended structures; flat, corrugated structure
Beta-Pleated sheets
secondary structure that has no apparent pattern
Random coils
Actual 3-dimensional structure of folding pattern of the protein
Tertiary Structure
tertiary structure is maintained by
covalent disulfide bond
responsible for many of the physical and chemical properties of proteins
tertiary structure
association of several polypeptide chains into larger “oligomeric” aggregate unit
quaternary structure
Quaternary structure is an association of several polypeptide chains into larger_
“oligomeric” aggregate unit
quaternary structure is maintained by_
non-covalent bond (hydrogen bond)
stable complexes of quaternary structure
- dimers
- trimers
- tetramers
examples of quaternary structure
- hemoglobin
- lactate dehydrogenase
- creatine phosphokinase
factors that cause loss of functions of proteins:
- heat
- hydrolysis by strong acid or alkali
- enzymatic reaction
- exposure to UV light
contain peptide chains that hydrolysis yield only AA
simple proteins
relatively symmetrical with compactly folded and coiled polypeptide chains
globular
examples of globular simple proteins
- hemoglobin
- plasma proteins
- enzymes
- peptide hormones
more elongated and asymmetrical and have a higher viscosity
fibrous
examples of fibrous simple protein
- fibrinogen
- troponin
- collagen
Protein (apoprotein) + nonprotein (prosthetic group)
conjugated proteins
prosthetic group
- lipid (lipoprotein)
- carbohydrate (glycoprotein)
- metals (metalloprotein)
types of simple proteins
a. globular
b. fibrous
major plasma proteins
- Pre-albumin
- Albumin
- Globulins
Migrates ahead of albumin in the classic electrophoresis of serum or plasma proteins
Pre-Albumin
Transport of thyroid hormones (thyroxine and triiodothyronine)
pre - albumin
binds with retinol-binding protein to form complex that transports retinol (Vitamin A)
pre-albumin
rich in tryptophan and contains 0.5% carbohydrate
pre-albumin
increased in pre-albumin
- alcoholism
- chronic renal failure
- steroid treatment
largest plasma protein fraction
albumin
what is the fraction of Albumin
52-62%
Synthesized in the liver at a rate that is dependent on protein intake
albumin
serves as circulating reservoir of AA
Albumin
regulator of osmotic pressure (fluid balance)
Albumin
Transport protein because of ease of binding with blood components
Albumin
indicator of nutritional status
albumin
reference values of Albumin
3.5 – 5.0 g/dL (35 – 50 g/L)
- No clinical significance
- Hemoconcentration, dehydration
- Excessive albumin infusion
Increased Albumin (Hyperalbuminemia)
- Impaired synthesis (primary= liver disease; secondary = diminished
protein intake) - Decreased synthesis (liver impairment)
- Malabsorption or malnutrition
- Nephrotic syndrome (renal loss)
- Severe burns
Decreased Albumin (Hypoalbuminemia)
Heterogenous complex mixture of protein molecules
(α1, α2, β and γ fractions)
Globulins
Elevated concentration of globulin in early cirrhosis will balance loss of albumin resulting to normal levels
of total protein
Globulins
Normal A/G ratio
1.3-3:1
Low Albumin/Globulin ratio causes
- liver diseases
- infectious diseases
- multiple myeloma
- nephritis
function of a-1-antitrypsin
inhibits protease neutrophil elastase
neutralize trypsin-like enzymes
a-1-antitrypsin
Major inhibitor of protease activity; inhibit lysosomal elastase released from PMNs during their response to particles & inhaled bacteria
a-1-antitrypsin
Most abundant protein in the fetal serum
a-1-fetoproteins
-Increased in amniotic fluid and maternal serum in
neural tube defects (spina bifida)
* Synthesized initially by the fetal yolk sac & then the
parenchymal cells of the liver
a-1-fetoproteins
a-1-fetoproteins is detectable in the maternal blood up to the ___ month of pregnancy
7th or 8th
a-1-fetoprotein peaks in the fetus at ___ weeks of gestation
13
maternal serum of a-1-fetoprotein increased in the presence of ___
twins
Diagnostic significance of AFP
- Detects neural tube defects
- Used as a tumor marker (hepatic & gonadal CA)
- Screening test for any fetal conditions, increase
passage of fetal proteins into the amniotic fluid;
detects neural tube defects
increased in AFP
- hepatoma neural tube defects (spina bifida),
- atresia of the GIT,
- fetal distress,
- ataxia telangiectasia,
- tyrosinosis,
- hemolytic disease of the newborn (HDN)
decreased in AFP
- trisomy 18
- down syndrome
other name for a-1-acid glycoprotein
orosomucoid
contains high percentage of CHO and sialic acid
a-1-acid glycoprotein
percentage of CHO in orosomucoid
45
percentage of sialic acid in orosomucoid
11-12
Synthesized both by the liver & by granulocytes and
monocytes
aag
Inhibits the phagocytic activity of neutrophils & inhibits
platelet aggregation
aag
May inactivate progesterone
aag
increased in aag( a -1 -acid glycoprotein)
-pregnancy,
-cancer,
-pneumonia,
-rheumatoid arthritis (RA),
-cell proliferation
Alpha 2- Globulins
- Haptoglobin
- Ceruloplasmin
the mature haptoglobin is a tetramer; how many chains
2a; 2b
synthesized in the hepatocytes, an acute-phase protein
haptoglobin
where is haptoglobin synthesized
hepatocytes
copper-containing protein BUT does NOT transport
copper; synthesized in the liver, where 6-8 copper
atoms are attached
ceruloplasmin
how many copper atoms are attached in ceruloplasmin?
6-8
Imparts a blue color to protein
ceruloplasmin
marker of wilson’s disease(0.1 g/L ceruloplasmin)
ceruloplasmin
Copper deposits in the cornea
Kayser-Fleischer ring
o Upon intake of copper, there is malfunction in the
transport systems within the cell
o No copper being absorbed in the brain, skin and
bones
o Absorbed only in the kidney which is directly
secreted in urine
o Primarily affects male infants
Menke’s syndrome
menke’s syndrome is also known as
Kinky hair disease
Carrier for iron (transferrin) and lipids (lipoproteins)
Beta Globulins
Beta globulins are increased in
- elevated beta lipoprotein (LDL)
- iron deficiency anemia
transferrin is also called as
siderophilin
A glycoprotein, is a negative acute-phase protein synthesized in the liver
tranferrin
Functions:
o Transport of iron
o Prevents loss of iron through the kidneys
transferrin
Tested to determine the cause of anemia, to gauge
iron metabolism, and to determine the iron-carrying
capacity of the blood
transferrin
increased in siderophilin
- hemochromatosis (bronze skin)
- Iron deficiency anemia
decreased in siderophilin
- liver disease
- malnutrition
- nephrotic syndrome
Gamma globulins increased in:
o Chronic inflammation
o Cirrhosis or viral hepatitis
o Collagen diseases
o Monoclonal gammopathies
gamma-globulins
o Congenital or acquired immunodeficiency
Are glycoproteins composed of 82% to 96% protein
and 4% to 18% carbohydrate produced by white
blood cells, known as B cells that confer humoral
immunity
immunoglobulins (Ab)
- Most abundant Ab found in plasma and lymph
- Usually fights on bacteria, viruses by agglutination
IgG
- Main Ab found in mucous secretions (tears, saliva
colostrum, vaginal fluid, respiratory and gastrointestinal mucosa secretions)
IgA
- First Ab that appears in response to antigenic stimulation
IgM
- Present mostly on the surface of B cells and its concentration increased in inflammation, liver
diseases and connective tissue disorders
IgD
- Associated with allergic and anaphylactic reactions,
parasitism
IgE
- One of the largest proteins in blood plasma
- Synthesized in the liver, and it is classified as a glycoprotein
Fibrinogen
- Most abundant coagulation factors
- An acute phase reactant
Fibrinogen
Transport cholesterol, triglycerides, and phospholipids in the blood
Lipoprotein
examples of lipoproteins
- chylomicrons
- VLDL (Very low density lipoprotein)
- HDL (High Density Lipoprotein)
- LDL (Low density lipoprotein)
One of the natural defense mechanisms that protects
the human body from infections
Complement
Participates in the immune reaction and serve as a link to the inflammatory response
complement
Circulates in the blood as nonfunctional precursors
complement
most abundant complement protein in the human
serum which is important in the pathogenesis of agerelated macular degeneration
C3
marker for assessing disease activity in rheumatic
disorders such as Rheumatoid Arthritis (RA) and
Systemic Lupus Erythematosus (SLE)
C3 and C4
- It precipitates with the C substance, a polysaccharide
of pneumococci - It may be undetectable in the blood of healthy
individuals
C-reactive protein
- It is a cardiac marker
- One of the most acute phase proteins that rise in
response to inflammatory diseases
C-reactive protein
- Also used as rapid test for presumptive diagnosis of
bacterial vs. viral infection
C-reactive protein
Miscellaneous proteins
- myoglobin
- troponins
- amyloid
A small heme protein found in skeletal and cardiac
muscles
myoglobin
When striated muscles are damaged, _____ is
released and it elevates blood levels
myoglobin
- Primary oxygen-carrying protein found in striated
skeletal and cardiac muscle - It has a greater affinity for oxygen than does hemoglobin
myoglobin
- As a cardiac biomarker, _______ has been used in
conjunction with troponin to help diagnose or rule out
a heart attack - In Acute Myocardial Infarction (AMI), the onset is 1-3
hours, peak level 5-12 hours, normalize in 18-30
hours
myoglobin
- Useful marker for monitoring the success of failure of
reperfusion
myoglobin
- A complex of 3 proteins that bind to the thin filaments of striated muscle (cardiac and skeletal)
- Diagnostic marker for identifying cardiac injury in the presence of skeletal muscle damage
troponins
Insoluble fibrous protein aggregates formed due to an
alteration in their secondary structure known as β-
pleated sheets
amyloid
amyloid is Insoluble fibrous protein aggregates formed due to an
alteration in their secondary structure known as ______
B-pleated sheets
Amyloid is a pathological extracellular deposit associated with group of disorders collectively called ________
amyloidosis
amyloid stains with what dye?
congo red
chief nitrogenous macromolecules of cellular structure and organization
protein
protein composes of ____ of the cell’s dry weight
50-70%
synthesized in the liver and secreted by the hepatocyte into the circulation except immunoglobulins
proteins
protein is synthesized in what organ?
liver
protein is secreted in the_
hepatocyte
Impaired synthesis (primary= ______; secondary = ______)
Liver disease; diminished protein intake
