Introduction to proteins Flashcards
what are the components of nucleic acids?
Phosphate group
Five Carbon Sugars (Ribose or 2’-deoxyribose)
Purine or pyrimidine base
the physiological function of the nucleic acid is based off what?
Structure
Purines contain how many rings and what are the examples?
purines contain 2 rings and are composed of adenine and guanine
pyrimidines contain how many rings and what are they composed of?
1 ring and the are composed of thymine, uracil, and cytosine
what are the sugars used for DNA and RNA?
ribose for rna and 2’-deoxyribose for dna
Thymidine is only found in what?
dna
uracil is only found in what?
rna
a nucleotide is formed by what?
the addition of at least one phosphate group to a nucleoside
a nucleotide is composed of how many parts and what are they?
it consists of 3 parts. purine/pyrimidine base, a five carbon sugar, and one to three phosphate groups
what does adenine bond with?
thymine
what does cytosine bond with?
guanine
what are the differences between dna and rna?
•rna’s sugar is ribose and dna’s sugar is 2’-deoxyribose
•the molecules are single stranded for rna as dna’s molecules are double stranded
•rna has the nitrogenous base uracil as opposed to dna’s thymine
what is transcription?
the synthesis of mrna. the dna information is copied into a strand of mrna
the three stages of transcription are what?
initiation
chain elongation
termination
what is mRNA responsible for?
responsible for genetic code. separated into codons out of the nucleus
what is rRNA responsible for?
responsible for building the protein by binding the amino acids together
what is tRNA responsible for?
responsible for correct amino acid sequence by using its anticodon to read the codon
an amino acid contains what?
at least one amino and one carboxylic acid functional group
amino acids differ from one another based off what?
chemical composition of the R groups (side chains)
amino acids metabolism and synthesis is where?
the liver
an amide bond is created when?
an amino group of one amino acid bonds to the carboxyl group of another forming the peptide bond
what is denaturation?
when there is unfolding of the protein structure and disruption of the secondary, tertiary, or quaternary structure
when can denaturation occur?
increases in temp
mechanical stress
extreme variations of the ph
organic solvents
detergents
what is bad about denaturation?
it is irreversible and results in loss of protein structure and function
what is RBP?
it serves as the transport protein for the active form of vitamin a
clinical significance of RBP?
-levels are increased in renal disease
-zinc deficiency is described as low serum concentration of rbp and vitamin a
clinical significance of TTR
indicator of protein nutrition because of its short half-life and high proportion of eaa’s. it responds more rapidly than other proteins. concentrations of ttr decrease with inflammation and inflammation and malignancy, cirrhosis and protein lose diseases of the gut of kidneys
Albumin accounts for what?
roughly on half of the overall plasma protein mass
about 60% of the total body pool of albumin is found where?
extravascular space
Albumin primary function serves as what?
major contributor to the COP (colloidal osmotic pressure)
albumin also serves as a ph buffer and binds to what?
free fatty acids
bilirubin
metallic ions
hormones
drugs
high levels of albumin can suggest what?
hydration problems or specimen handling problems. this includes prolonged tourniquet use, specimen evaporation, or patients with excessive albumin infusions
how do labs test for albumin?
dye binding methods in plasma or serum using either green or purple as both of these dyes have a high affinity for albumin and low affinity for other proteins
what is the function of AFP (a-fetoprotein)?
binds and transports the hormone estradiol
elevated levels of afp are associated with conditions in fetuses such as what?
abdominal wall defects
general fetal distress
neutral tube defects such as spine bifida and anencephaly
increased levels and decreased levels of APF in pregnant mothers are a sign of what
increased levels could be seen in mothers with twins and decreased levels could be seen in edwards syndrome and down syndrome
a1-acid glycoprotein (AAG)
member of the lipocalin family. AAG binds to basic drugs including propranolol, quinidine, chlorpromazine, cocaine, and benzos. levels will increase with GI inflammatory disease, corticosteroids, and malignant neoplasms.
a1-antitrypsin (AAT)
it is a serpin that inactivated serine proteases. it serves as the inhibitor for leukocyte elastase. when deficient in leukocyte elastase, it causes damage to the elastins of the lungs. if it continues it can turn into emphysema. increases to AAT can be seen in patients with estrogen level elevations. decreases can be seen in patients with severe pancreatitis and protein losing disorders.
Haptoglobin
a glycoprotein that binds to free hemoglobin. regulation of free haptoglobin protects nitric oxide in the blood stream. levels can drop on the blood stream when intravascular hemolysis occurs.
a2-Macroglobulin
synthesized by the liver and is one of the major plasma proteinase inhibitors. AMG inhibits enzymes like serine, cysteine, and metal ions in their catalytic sites. it is activated by proteolytic cleavage then reacts by binding to the proteases. AMG can assist in determining prognosis and monitoring treatment. increases are seen in patients with nephrotic syndrome, diabetes, and increased estrogen levels. decreases in AMG are seen in individuals with acute pancreatitis or advanced prostate cancer.
Ceruloplasam
is an a2 globulin that is made up of 95% of the total serum copper. it has a blueish tint to it. the primary role is to serve as a catalyst for redox reactions. oxidizing iron from Fe2 to Fe3. Cp concentration is low in patients with blood loss, GI protein losing syndromes, renal protein losing syndromes, or deficiency of copper. elevated levels occur in severe infection, inflammation, and tissue damage.
Wilson Disease
genetic disorder resulting in copper levels increased significantly and being deposited into the tissues including the liver, brain, and the periphery of the iris.
Transferrin
is synthesized by the liver and is found in the B region on a serum electrophoresis strip. Iron levels are highest in the morning and the lowest in the evening. morning specimens are preferred.
B2-microglobulin
is a small protein of 11.8kDa, that is found on the surface of nucleated cells and in especially high numbers on lymphocytes. normally less than 1% of filtrated BMG is excreted in the urine. for hiv patients, monitoring BMG levels can help indicate lymphocyte turnover. also used as a tumor marker for certain blood cancers and staging of multiple myeloma.
Fibrinogen
is critical to the coagulation system and one of the largest plasma proteins. coagulation factors including fibrinogen are mainly produced in the liver. it assist in clot formation after it is cleaved by thrombin. low levels of fibrinogen are the result of usage to control extensive bleeding or problem with the coagulation system. fibrinogen is typically measured using functional assays that evaluate clotting.
C-reactive protein
synthesized by the liver and is one of the fastest and strongest acute phase proteins to elevate in response to inflammatory disease. level rise 6-12 hours once injury/disease triggers it. it assists in protecting the body against infectious organisms and cleaning tissue debris.
C reactive protein is elevated in what?
acute rheumatic fever
bacterial and viral infections
myocardial infarctions
rheumatoid arthritis
gout
spreading cancer
Complement
complex system of at least 20 different proteins. part of the immune system.
the classic pathway
is activated primarily by complexes of antibodies/immunoglobulins and CRP
the alternative pathway
activated by bacterial lipopolysaccharides, cellular proteases, and cobra venom
Immunoglobulins
antibodies are produced as a result of the body encountering foreign immunogens and are not produced by the liver. they are produced by plasma cells which are produced by B lymphocytes.
IgG
most abundant antibody found in blood plasma and lymph making up 70-75% of total Ig. it’s able to cross the placenta. IgG’s serum in newborns are synthesized by the mother.
IgM
serves as the first responder. it is the first ab to appear in response to antigenic stimulation.
IgA
makes up 10-15% of total serum ig and has 2 subclasses. it is the main antibody in many body fluids. it has a special structural feature called secretory unit where it can be transported into secretions.
IgE
the antibody most associated with allergic reactions and anaphylactic reactions. it has a monomer structure which rapidly and firmly bunds to mast cells
Cryoglobulins
serum proteins that precipitate at temperatures lower than normal core body temperatures. precipitation in the tissues result in vasculitis and ischemic injury.
Kjeldahl Method
quantifying the amount of nitrogen present in proteins. it’s converted into ammonium ions using acid digestion process. the ammoniums are then quantified using titration. then multiplied by 6.25 to obtain final values. highly accurate however time consuming and serves as a mean to validate reference materials
Dye Binding method
relies on the shifts in the absorbance spectra of dyes when they are bind to proteins. common dyes used are…
Bromocresol green or purple
coomassie brilliant blue
amido black
ponceau S
Lissamine green
Biuret method
measures the reaction of peptide bonds in proteins which bind to alkaline conditions to Cu2. the binding cause a shift in absorption spectra leading to color change which is readable at 540nm. the reaction is a blue color due to high levels of Cu2. color change with vary from pink to reddish violet color. the more the color change, the more peptide bonds were present
Direct photometric
absorbance of UV light at 200nm to 225nm and 270nm to 290nm are used to measure the protein content in biological fluids. bilirubin and uric acid absorb light around 280nm. this method may require removal of low molecular weight items using gel filtration.
Turbidimetric and Nephelometric methods
both techniques access the formation of aggregates when reagent is added to lower protein solubility or when antibody is added to protein. Turbidimetric measures the changes in absorbance caused by the formation of the aggregates. Nephelometry is similar except it measures with the detector at and angle to read the light reflected.
Electrophoresis
used to measure protein content in biological fluids. this method is different because it measures overall protein content. Dyes used to stain the proteins are Ponceau S, Amido black, and Coomassie brilliant blue (most sensitive)
Immunofixation electrophoresis
uses antibodies in the agarose gel to separate the antibodies for evaluation of the individual classes igM, igG, and igA
