Amino Acids and Proteins Flashcards
Plasma proteins are the most commonly analyzed proteins and can be divided into 2 major groups:
Albumin
Globulins
It migrates before albumin in classic serum protein electrophoresis (SPE)
Prealbumin or transthyretin
It is a transport protein for the thyroid hormones, thyroxine, and triiodothyronine.
Prealbumin or transthyretin
Prealbumin has a half-life of approximately ___.
2 days
It is synthesized in the liver at the rate of 9 to 12 g/day and it is the most abundant protein in the plasma.
Albumin
Albumin is a _____ acute pjase reactant
Negative
Primary function of albumin is?
Its capacity to bind and transport various substances in the blood.
Represents trends in blood glucose over a period of 3 months or approximately 120 days.
Glycated Hemoglobin
The primary site for protein synthesis is?
Liver
Absence of albumin in known as
Analbuminemia
Presence of albumin that has unusual molecular characteristics is referred to as?
Demonsrrated by the presence of two albumin bands instead of a single one during electrophoresis
Bisalbuminemia
- a glycoprotein synthesized in the liver.
- its main function is in the inhobition of the protease, neutrophil elastase.
- positive acute-phase reactant
a1-antitrypsin
Mutations in the ______ gene can lead to a deficiency of a1-antitrypsin protein or an abnormal form of the protein that does not properly control neutrophil elastase
SERPINA1 gene
Quantitative methods used to confirm a1-antitrypsin deficiency are (2)
Radial immunodiffusion
Automated immunonephelometric assays
- is synthesized in utero by the developing embryo and fetus and then by the parenchymal cells of the liver.
- it protects the developing fetus from immunologic attack by the mother.
- reaches adult concentration at 8-12 months.
a1-Fetoprotein (AFP)
AFP screening is performed between ___ and _____ weeks of gestations when maternal AFP gradually increases; therefore,interpretation requires accurate dating of pregnancy.
15-20 weeks
The methods commonly used in AFP determination is (2)
Radioimmunoassay (RIA)
Enzyme-labeled Immunoassay (EIA)
AFP may also be used as a tumor marker and is fractionated by affinity electrophoresis into three isoforms (L1, L2, and L3) based on their reactivity with the lectin _______.
Lens culinaris agglutinin (LCA)
It is now being considered as a tumor marker for the North American population for screening chronic liver disease patients for hepatocellular carcinoma (HCC)
AFP-L3
- is a major plasma glycoprotein that is negatively charged even in acidic solutions lending to its name.
- produced by the liver and is a positive acute-phase reactant.
- serum _____ concentrations are also used in the diagnosis and evaluation of neonatal bacterial infections.
a1-Acid glycoprotein (AAG) or orosomucoid
The analytic methods used most commonly for the determination of AAG are (3)
Radial immunodiffusion
Immunoturbidity
Nephelometry
- is an a-globulin glycoprotein that is a member of the serine proteinase inhibitor (serpin) family.
- it inhibits the activity of the enzymes cathepsin G, pancreatic elastase, mast cell chymase, and chymotrypsin by cleaving them into a different shape (conformation).
- produced in the liver and is a positive acute-phase reactant that increases during inflammation.
a1-Antichymotrypsin
- are a family of serine protease inhibitor l, assembled from two precursor proteins: a light chan and one or two heavy chains.
- have been shown to play a particular role in inflammation and carinogenesis.
Inter-a-Trypsin inhibitor
- is also known as a group-specific component or vitamin D-binding protein.
- synthesized by the hepatocytes and is the mahor carrier protein for vitamin D and its metabolites.
- it also transports components such as fatty acids and endotoxins.
Gc-globulin
- The resulting decrease in ____ concentration makes it usable as a prognostic indicator of survival of patients with significant tissue injury after trauma and among patients with hepatic failure.
-it may be of importance for bone formation and in the immune system.
Gc-Globulin
What is the method of choice for Gc measurements?
Immunonephelometry
- it is an a2-glycprotein synthesized in the liver and is a tetramer consisting of two a and two b chains.
- its primary function is to bind free hemoglobin to prevent the loss of its constituent, iron, into the urine.
- it is a positive acute-phase reactant that increases in many inflammatory diseases, such as ulcerative colitis, acute rheumatic disease, acute myocardial infarction, and severe infection.
Haptoglobin
Quantitative determination for haptoglobin (2)
Radial immunodiffusion
Immunonephelometric methods
- is a copper-containing, a2-glycoprotein enzyme that is synthesized in the liver.
- it is a positive acute-phase reactant and is frequently elevated in inflammation, severe infection, and tissue damage and may be increased with some cancers.
Ceruloplasmin
Ceruloplasmin is primarily measured along with blood and urine copper test to aid in the diagnosis of?
Wilson’s disease
The analytic method of ceruloplasmin determination was based on its _______ activity. Most assays today use immunochemical methods including (2)
Copper oxidase activity
Radial immunodiffusion
Nephelometry
- is a tetramer of four identical subunits that is synthesized by the liver and is a major component of the a2-band in protein electrophoresis.
a2-Macroglobulin
Analytic methods used for measurement of a2-macroglobulin are (4)
Radial immunodiffusion
Immunonephelometry
Enzyme-linked immunosorbent assay (ELISA)
Latex agglutination immunoassay
- is a negative acute-phase glycoprotein synthesized by the liver.
- it is a major component of b-globulin fraction on protein electrophoresis and plays an important role in the transport of iron.
- it also carries iron to other sites, such as the bone marrow, that synthesize hemoglobin and other iron-containing compounds.
Transferrin or siderophilin
____ prevents iron from being inappropriately deposited in tissues during temporary increases in absorbed iron or free iron.
Transferrin
An increase of iron bound to transferrin is found in hereditary disorder of iron metabolism, known as ______ in which excess iron is deposited in the tissue, especially in the liver and the pancreas l.
hemochromatosis
It is inherited as an autosomal recessive trait due to mutation of both transferrin genes, with a resulting absence of transferrin.
Atransferrinemia
Analytic methods used for the quantitation of transferrin (2)
Immunodiffusion
Immunonephelometry
Total serum iron is low, but TIBC is increased, and transferrin saturation becomes very low.
Iron deficiency
Total serum iron is high and TIBC is low or normal, causing transferrin saturation to increase.
Iron overload
- the parenchymal cells of the liver synthesize ____, which migrates electropheretically in the b-globulin region and is an acute-phase reactant.
- its main function is to bind with free heme.
Hemopexin
Heme-hemopexin complex is carried to the liver and has a ration of?
1:1
Hemopexin determinations are performed by?
Radial immunodiffusion
Are complexes of proteins and lipids whose function is to transport cholesterol, triglycerides, and phospholipids in the bloodstream.
Lipoproteins
In high-resolution electrophoresis, HDL migrates between the?
Albumin and a1-globulin zone
In high-resolution electrophoresis, VLDL migrates at the?
Beginning of b-globulin fraction (pre-b)
In high-resolution electrophoresis, LDL appears as?
A separate band in the b-globulin region
It is the light chain component of the major histocompatibility complex or human leukocyte antigen (HLA)
b2-Microglobulin (B2M)
B2M is usually measured by?
Immunoassay
- is a natural defense mechanism that protects the human body from infection.
- these proteins are synthesized in the liver as a single polypeptide chains and circulate in the blood as nonfunctional precursors.
Complement system
Complement ______ is the most abundant complement protein in the human serum, with complement ______ being the second abundant
C3; C4
Methods measuring complements include (2)
Nephelometric immunoassay
Turbidimetry
- it is one of the largest proteins in the blood plasma.
- it is synthesized in the liver and classified as a glycoprotein.
- it is a positive acute-phase reactant and increases significantly during an inflammatory process.
Fibrinogen
- it is synthesized in the liver and is one of the first acute-phase proteins to rise in response to inflammatory disease.
C-reactive protein (CRP)
CRP is generally measured by immunologic methods including (2)
Nephelometry
EIA
- is the C-reactive protein, but is named for a monoclonal antibody-based test methodology that can detect CRP levels below 1mg/L.
- most commonly used to determine risk of CVD.
High-sensitivity CRP (HsCRP)
- are glycoproteins composed of 82% to 96% protein and 4% to 18% carbohydrate.
- produced by white blood cells known as B cells.
Immunoglobulins or antibodies
Immunoglobulins: the N-terminal regions of the heavy and light chains exhibit highly variable amino acid composition referred to as VH and VL, respectively. This variable region is involved in?
Antigen binding
The constant domains of light and heavy chains are referred to as CL and CH, respectively. The constant regions are involved in?
Comolement binding
Is a biologic mechanism that changes an antibody from one class to another.
Immunoglobulin class switching or isotype switching
Immunoglobulins have been determined using (5)
Radial immunodiffusion
Nephelometry
Turbidimetry
Electrochemiluminescent immunoassay (ECLIA)
RIA
- is a single-chain globular protein of 153 amino acids, containing a heme prosthetic group.
- it is the primary oxygen-carrying protein found in striated skeletal and cardiac muscle, accounting for approximately 2% of total muscle protein.
Myoglobin
It can reversibly bind oxygen similarly to the hemoglobin molecule, but _______ requires a very low oxygen tension to release the bound oxygen.
Myoglobin
What are the most commonly used methods for myoglobin measurements? (5)
Latex agglutination
ELISA
Immunonephelometry
ECLIA
Fluoroimmunoassay
Represents a complex of regulatory proteins that include troponin C (TnC), troponin I (cTnI), and troponin T (cTnT) that are specific to cardiac muscle.
Cardiac troponin
Are considered the “gold standard” for diagnosis of acute coronary syndrome (ACS) in which the blood supply to the heart muscle is suddenly impeded.
Cardiac troponin
Cardiac troponins can be measured using (2)
ELISA
Immunoenzymometric assay
Are a family of structurally related hormones that include atrial natriuretic peptide (ANP), B-type (or brain) natriuretic pepdtide (BNP), C-type natriuretic peptide (CNP), and Dendroaspis natriuretic peptide (DNP).
Natriuretic peptides
Are neurohormones that affect body fluid homeostasis, through natriuresis and diuresis, and blood pressure, through decreased angiotensin II and norepinephrine synthesis.
Natriuretic peptides
Laboratory methods for measuring BNP and NT-proBNP include (3)
RIA
Microparticlr enzyme immunoassay (MEIA)
ECLIA
- is a glycoprotein composed of two nearly identical subunits.
- these proteins are found in plasma and on cell surfaces and can be synthesized by hepatocytes, endothelial cells, and peritoneal macrophages, abd fibroblasts.
Fibronectin
It is used to help predict the short-term risk of premature delivery.
Fetal fibronectin
Is a 247-amino acid hormone composed of an N-terminal collagen-like domain and a C-terminal globular domain produced by adipocytes.
Adiponectin
- is a 168-amino acid, low-molecular-mass protein in the lipocalin protein family.
- established as an accurate marker of cerebrospinal fluid leakage and have also been used as a potential marker in detecting impaired renal function through BTP is no more sensitive than custatin C.
B-trace protein (BTP) or prostaglandin D synthase
- are proteolytic fragments of collagen I formed during bone turnover, and their presence in serum and urine is a biochemical marker of bone resorption.
- useful in monitoring response to antiresorptive therapy as it is noninvasive and can be repeated often.
Cross-linked C-telopeptides(CTXs)
What method is used for CTX measurement?
ECLIA
- a low molecular-mass protein with 120-amino acids, is a cysteine proteinase inhibitor.
- it is freely filtered by the glomerulus and almost completely reabsorbed and catabolized by the proximal tubular cells.
Cystatin C
Cystatin C measurements may be performed by (2)
Particle-enhanced immunoturbidimetric or immunonephelometric methods
Are insoluble fibrous protein aggregates formed due to an alteration in their secondary structure known as b-pleated sheets.
Amyloid
Refers to conditions in which amyloids are abnormally deposited in organs and tissues, including the heart and blood vessels, brain and peripheral nerves, kidneys, liver, spleen, and intestines, causing localized or widespread organ failure.
Amyloidosis
A total protein concentration below the reference interval, occurs in any condition where a negative nitrogen balance exists.
Hypoproteinemia
An increase in total plasma proteins, is not associated with disease state, but is commonly the result of dehydration.
Hyperproteinemia
A total nitrogen determination measures all chemically bound nitrogen in the specimen and can be performed on various sample types, but is most commonly performed using?
Plasma
The most common method for total nitrogen analysis uses?
Chemiluminescence
The specimen most used to determine totak protein concentration is?
Serum
Total protein methods: the classic method for quantitation of total protein is the ____ method, which measures the amount of nitrogen in the specimen.
- this method is no longer routinely used in the clinical lab because it is time consuming and relies on some assumptions that are not always true
Kjeidahl method
Total protein methods: is the most widely used method for the determination of total protein and is recommended by the International Federation of Clinical Chemistry expert panel.
Biuret
Total protein methods: based on the ability of most serum proteins to bind dyes, although the affinity with which they bind may vary.
Dye binding
Globulins are separated from the albumin by a precipitation process using sodium salt
Salt fractionation
The most widely used method for determining albumin are?
Dye-binding procedures
Building blocks of protein
Amino acids
The amino group of one amino acid can be linked with the carboxyl group of another amino acid forming a?
Peptide bond
When a chain of amino acifs is linked by peptide bonds, it known as?
Polypeptide
A large polypeptide constitutes a?
Protein
What are the essential amino acids? (10)
Arginine
Histidine
Isoleucine, Leucine, Valine
Lysine
Methionine
Phenylalanine
Threonine
Tryptophan
What do you mean by essential amino acids
- is a complex amino acid often found at the catalytic (active) site in proteins and enzymes due to its amine-containing side chain.
- plays an important role in cell division, wound healing, stimulation of protein synthesis, immune function, and release of hormones.
- one important role is the conversion of ammonia into urea.
Arginine (Arg)
- one of the basic by pH amino acids due to its imidazole side chain.
- 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 (His)
Are branched chain amino acid
Isoleucine (Ile), Leucine (Leu) and Valine (Val)
Branched chain amino acid group: plays an important role in hemoglobin formation
Isoleucine (Ile)
Branched chain amino acid group: necessary for optimal growth in infants
Leucine (Leu)
Branched chain amino acid group: both aid in maintaining the nitrogen valance in adults
Leucine (Leu) and Valine (Val?
Branched chain amino acid group: used in treatments for muscle, mental, and emotional problems such as insomnia and anxiety, as well as liver and gallbladder disease.
Valine (Val)
- has a net positive charge, which makes it one of three basic, by charge,
amino acids. - It plays a role in the production of antibodies and lowering triglyceride levels.
- also helps in the absorption and conservation of
calcium and plays an important role in the formation of collagen, a component of
cartilage and connective tissue.
Lysine (Lys)
- is an important amino acid that helps to initiate translation of
messenger RNA (mRNA) by being the first amino acid incorporated into the Nterminal position of all proteins - is a source of sulfur, which is
required for normal metabolism and growth - also assists in the
breakdown of fats, helps to detoxify lead and other heavy metals, helps diminish
muscle weakness, and prevents brittle hair
Methionine (Met)
- is classified as a nonpolar amino acid because of the hydrophobic
nature of its benzyl side chain. It promotes alertness and vitality, elevates mood,
decreases pain, aids in memory and learning, and is used to treat arthritis and
depression. - is used by the brain to produce norepinephrine, a
neurotransmitter that transmits signals between nerve cells
Phenylalanine (Phe)
- is an alcohol-containing amino acid that is an important component in
the formation of collagen, elastin (a connective tissue protein), and tooth enamel - helps maintain proper protein balance in the body
and aids liver function, metabolism, and assimilation.
Threonine (Thr)
- is a metabolic precursor for serotonin, melatonin (a neurohormone),
and niacin (a vitamin). - is a natural relaxant that helps alleviate
insomnia by inducing sleep, soothes anxiety, and reduces depression.
Tryptophan (Trp)
What are the nonessential amino acids? (10)
Alanine
Asparagine
Aspartic acid
Cysteine
Glutamic acid
Glutamine
Glycine
Proline
Serine
Tyrosine
What does it mean by nonessential amino acids
