Amino Acids Flashcards
What is the functional structure of amino acids
They’re simple, organic compounds that are the building blocks for proteins. They contain one amino group (N-terminal) and one carboxyl group (C-terminal), and are linked together with peptide bonds
Absorption of amino acids takes place where? Where do dietary proteins and amino acids not absorbed take place?
Absorption takes place in the small intestines into the bloodstream.
The ones that do not are excreted in feces
What are essential amino acids and which ones are they?
they’re the amino acids that cannot be synthesized in vivo fast enough and must be acquired by diet.
- histidine
- isoleucine
- leucine
- methionine
- phenylalanine
- theonine
- tryptophan
- valine
what are non-essential amino acids and which ones are they?
the body can synthesize adequate amounts of these, so dietary intake isn’t necessary
- alanine
- asparagine
- aspartic acid
- glutamic acid
- selenocysteine
- serine
Gastrin stimulates the secretion of what two things to promote the denaturation of proteins?
HCl (hydrochloric acid) and pepsin
Proteins catalyze almost all reactions in living cells. What are five of their functions?
- biochemical reactions
- transporting metals
- acting as receptors for hormones
- providing structure and support
- being part of the immune response
What causes maple syrup urine disease? What are some of the symptoms?
deficiency in branched chain keto acid decarboxylase. Leads to excess branched chain amino acids (valine, leucine, and isoleucine), which causes metabolic acidosis
maple syrup odor urine, seizures, coma, death
phenylketonuria is caused by what? What are some symptoms?
inability to metabolize phenylalanine
- this test is done on newborns
mousy odor urine, cerebral development loss, loss of interest, mental retardation, restlessness, and irritability
What causes cystinuria and what are some symptoms?
defect in renal tubule transport protein affecting dibasic amino acids
causes cystine kidney stones and crystalluria
what causes alkaptonuria and what are the symptoms?
inability to properly degrade tyrosine/defect in homogentistic acid
black urine and black cartilage and arthritis
What are parameters to be met when testing amino acids?
-blood samples after a fast
- heparin tube (Plasma removed)
- perform immediately or freeze at -40ºC
- urinary amino acid testing can be performed on random samples
- thin-layer chromatography
What are the five elements that make up protein structure? What are the four levels of protein structure?
Carbon, oxygen, hydrogen, nitrogen, and sulfur
- primary: number, type, and sequence of aa in a polypeptide chain
- secondary: commonly formed arrangements (alpha-helix and beta-pleated sheets) stabilized by hydrogen bonds between amino acids
- tertiary: the overall shape or conformation of the protein molecule
- quaternary: the interactions of one or more protein molecule (subunit) to function as a single unit (multimer)
What part of the protein changes the property of the protein? What determines if the protein is negatively or positively charged?
amino acid side chain (R group) changes the protein properties. Proteins are pos or neg charged due to the N- or C- terminal ends
What are the two protein groups that are not involved in the peptide bond/can exist in different charged forms depending on the pH of the surrounding environment? What happens when the pH of a solution increases?
the acid or base groups
as pH goes up,
- carboxyl groups become carboxylate
- ammonium groups to amino groups
What is the isoelectric point, and what happens when the pH increases or decreases from it?
isoelectric point: pH at which amino acid or protein has NO net charge
- pH greater than isoelectric point: net neg charge
- pH less than isoelectric point: net pos charge
Where are plasma proteins synthesized before being excreted into circulation? What is amino acids sequence determined by?
protein synthesis occurs in the liver
aa sequence determined by corresponding sequence of nitrogen bases of DNA (three-nucleotide combination = codon)
what is transcription and translation of protein synthesis?
transcription: formation of complementary strands of mRNA in the nucleus to be used as a template
translation: moving the mRNA across the nuclear membrane to the cytoplasm; then the mRNA strand threaded into the ribosome provided the RNA sequence for the codons with their corresponding aa’s to form a polypeptide chain
Proteins have no designated storage. They are repeatedly _____ and then _______. What is maintained by equal intake and excretion of amino acids? What happens when there is too much or too little of this substance?
they’re repeatedly synthesized and then degraded
Nitrogen balance is maintained by aa intake and excretion
Too little nitrogen: excessive tissue destruction, burns, starvation
Too much nitrogen: aa converted to urea for kidney excretion and into glucose or ketones for energy
Classification of proteins depend on what three things? What two classes (and subclasses) of proteins are there?
based on structure, composition, and function
- simple proteins: upon hydrolysis, yield only amino acids (eg albumin and troponin)
- conjugated/complex proteins: composed of a protein and a non-protein moiety
- enzymes, hormones, immunoglobulins
Routine analysis measurement of protein includes what three parts? What are three functions of plasma proteins?
measurement of total protein, albumin, and A/G (albumin/globulin) ratio
functions: catabolism, nitrogen balance, and hormone regulator
What is prealbumin, what is it a marker for in CSF, and what do increased and decreased concentrations indicate?
transport protein for thyroid hormones T3 and T4 (thyroxine and triiodothyronine).
Forms a complex with retinol-binding protein to transport vitamin A in CSF
Marker for nasal discharge
- decreased: hepatic damage, tissue necrosis, and poor nutrition
- increased: steroid therapy, alcohol abuse, and chronic renal failure
What is the roles of albumin?
maintains homeostatic pH by serving as a buffer in circulation and maintains the fluid balance between extra- and intra-vascular spaces (colloid osmotic pressure). It also binds bilirubin
negative acute phase protein
most abundant in plasma
what do increased and decreased concentrations of albumin indicate?
increased: not usually significant, but can mean dehydration
decreased: acute inflammatory response, liver/kidney disease, malabsorption/nutrition
What is the function of alpha-1-antitrypsin (A1AT), what kind of globulin is it, and what do increases and decreases of it signify?
positive acute phase reactant glycoprotein that functions to inhibit neutrophil elastase
-it’s a major protease inhibitor
it’s a alpha-1-globulin
increase: inflammation, pregnancy, contraceptive use
decrease: lung damage, emphysema
What is the function of alpha-2-macroglobulin, what kind of globulin is it, and what is the significance of its increase and decrease?
it’s an alpha-2-globulin that acts as a protease inhibitor (eg for insulin and pepsin)
regulates growth factors and cytokines
increased in:
- nephrotic syndrome due to its size, pregnancy, renal disease (secondary to diabetes mellitus)
decreased in:
- pancreatitis and liver disease
associated w/Alzheimer’s
Where is alpha-1 fetoprotein made, what kind of globulin is it, and what are is the significance of its increase or decrease?
it’s an alpha-1 globulin made in utero
increase: inflammation, increased risk of spina bifida, neural tube defects, and general fetal distress
decrease: risk marker for Down syndrome
What is the function of alpha-1 glycoprotein and what is the significance of its increase?
it maintains the barrier function of capillaries, regulates immunity, and binds endogenous/exogenous substances
made mostly from carbs
increase: stress, inflammation, tissue damage, AMI, trauma, pregnancy, cancer, pneumonia, RA and surgery
What is the function of haptoglobin, what kind of globulin is it, and what is the significance of its increase and decrease?
An alpha-2 globulin that binds to free Hgb to prevent the loss of iron in the urine. Used to evaluate primary hemolytic anemias, and aids in distinguishing intra from extravascular hemolysis
increase: inflammation, ulcerative colitis, acute rheumatic disease, AMI, and severe infection
decrease: hemolytic anemia and decreased liver synthesis
What is the function of ceruloplasmin, what kind of glycoprotein is it, and what is the significance of its increase and decrease?
An alpha-2 glycoprotein that transports copper and is measure in blood and urine to diagnose Wilson’s disease (AR disorder)
increased: inflammation, infection, tissue damage, some cancers, pregnancy, estrogen ingestion / oral contraceptives
decreased: Wilson’s disease (with Kayser Fletcher rings in eyes), malnutrition/malabsorption, severe liver disease, nephrotic syndrome, Menke’s syndrome (decrease copper adsorption)
What is the function of transferrin, what kind of globulin is it, and what is the significance of its increase or decrease?
it’s a beta globulin, negative acute phase reactant, and binds iron to and from storage
increase: IDA (due to the body trying to compensate for loss of iron)
decrease: liver disease, insufficient intake of proteins, nephrotic syndrome (it’s lost through the kidneys)
What is beta-2 microglobulin, and what is the significance of its increase?
it’s the light chain component of the MHC or HLA, and found in high concentrations on lymphs
increased in plasma:
- impaired renal clearance or overproduction (due to inflammatory diseases like SLE)
- in HIV: high B2M in absence of renal failure means large lymph turnover rate
increased in urine:
- renal tubular damage/disease
What is the function of fibrinogen, what kind of globulin is it, where should you not find it, and what is the significance of its increase and decrease?
It’s a beta globulin, one of the largest proteins in the blood plasma, and functions to form a fibrin clot when activated by thrombin.
Shouldn’t see it in serum
increase: inflammation, pregnancy and oral contraceptives
decrease: excessive coagulation and fibrinogen disorders (a/ hypofibrinogenemia)
What is C-reactive protein, what kind of globulin is it, and what are conditions related to its increase?
It’s a beta-globulin that is one of the first acute-phase reactant to rise in response to inflammatory disease. hs-CRPLevels help determine risk of cardiovascular disease.
increase: SLE or RA, rheumatic fever, bacterial/viral infection, gout, active coagulation, and atherosclerosis (which activates complement)
(CRP over 1 mg/dL is considered high)
What is the main complement protein, what kind of globulin is complement, and what is the significance of its increase and decrease?
C3 is a beta globulin
increase: inflammation
decrease: malnutrition, SLE, and intravascular coagulopathies (DIC)
Immunoglobulin structure types, classes, function, and what kind of globulin are the immunoglobulins?
Structure can be: monomer (IgG/D/E), dimer (IgA) or pentamer (IgM)
Immunoglobulins are gamma globulins made from two identical light chains (kappa and lambda) and two identical heavy chains (the Ig classes)
What are special characteristics of IgG, and what do increases and decreases of it mean?
Most abundant Ig
second responder to bacteria, fungus, and viruses by agglutination, opsonization, and complement activation and neutralizing toxins
can cross the placenta
increased: liver disease/autoimmune disease
deceased: acquired immunodeficiency and increased susceptibility to infections
What are the special characteristics of IgA, and what is the significance of its increase and decrease?
main Ig found in mucous secretions (eg tears, saliva, vaginal fluid, respiratory/GI mucosa). Made by B lymphs.
Increase: liver disease, autoimmune disease, nutritional hepatic cirrhosis
Decrease: immunodeficiency and impaired protein synthesis
What are the unique characteristics of IgM and what are the significances of its increase and decrease?
First Ig to appear in a antigenic stimulation, is a pentamer, only Ig made by the neonate
Increase: bacteria infections, toxoplasmosis, primary biliary cirrhosis, CMV, rubella/herpes
Decrease: hereditary immunodeficiencies, and protein-losing deficiencies
Where are IgD found/made? What is the significance of its increase and decrease?
Present on the surface of most (but not all) B lymphs in their development. Most don’t get released into circulation
increase: infection, liver disease, and connective tissue disorders (SLE and RA)
What is the significance of its increase and decrease of IgE
allergic and anaphylactic reactions, autoimmune processes, and parasitic infections
(circulation is low)
What is troponin and its functions, as well as what is the significance of its increase?
three proteins that bind to filaments of striated skeletal muscle and cardiac muscle that are highly cardio-specific
gold standard measurement analyte for diagnosis of acute coronary syndromes
- Myocardial infarction, embolus, myocarditis, pericarditis, heart failure, intracranial insults, and sepsis
What is beta-type natriuretic peptide?
A hormone released from ventricular walls due to hypertension and volume overload. It increases Na+ / water excretion, and vasodilation to lower blood pressure
Seen in patients with heart failure
What is evaluated by total protein measurements, and what are the two main kinds of abnormal protein abnormalities?
Total protein measurements evaluates:
- nutritional status
- kidney disease
- liver disease
Hypoproteinemia and hyperproteinemia
Hypoproteinemia is cause by?
excessive loss: renal disease, leakage into GI tract, blood loss, extensive burns
decreased synthesis: liver disease
increases protein catabolism: in burns, trauma, or other injuries
hyperproteinemia is caused by?
dehydration:
- water loss in vessels while proteins remain in vessels
- vomiting, diarrhea, excessive sweating, diabetic acidosis, monoclonal protein production, and hypoaldosteronism
What is Bence Jones protein, and what does it signify?
Bence Jones proteins are urine specific proteins (Ig light chains) in patients with plasma cell disorders:
- Multiple myeloma
- Waldenstrom’s macroglobulinemia
What are three body fluids used to analyze serum proteins? What is electrophoresis, immunofixation, and immunoelectrophoresis?
urine, CSF, and serum
electrophoresis: separates proteins on the basis of their electric charge and density across agarose gel or cellulose acetate
immunoelectrophoresis: electrophoresis, and then antibodies are applied, diffuse onto a plate, and interact with patient antigens to make a line of precipitation
immunofix: insoluble antigen-antibody complexes (made with antiseras) that precipitate
what is the order of protein electrophoresis migration (fastest to slowest) at a pH of 8.6?
Albumin, alpha-1 globulin, alpha-2 globulins, beta globulins, and gamma globulins
Name the 3 alpha-1 globulins, 3 alpha-2 globulins, 5 beta globulins, and gamma globulins
alpha-1:
- alpha-1 antitrypsin
- alpha-1 fetoprotein
- alpha-1 glycoprotein
alpha-2:
- haptoglobin
- ceruloplasmin
- alpha-2 macroglobulin
beta:
- transferrin
- beta-2 microglobulin
- fibrinogen
- complement
- C-reactive protein
gamma: all immunoglobulins
Nephrotic syndrome electrophoresis change from normal
decreased albumin, increased alpha-2, decreased gamma
monoclonal gammopathy electrophoresis change from normal
sharp spike in gamma region
hypogammaglobulinemia electrophoresis change from normal
flat gamma band
liver disease/cirrhosis electrophoresis change from normal
decreased albumin and broad increase of gamma (beta-gamma bridging)
acute inflammation / phase reaction electrophoresis change from normal
increased alpha-2 globulins (with a chance of decreased albumin)
polyclonal gammopathy electrophoresis change from normal
broad increase of gamma globulins only
what is the difference between hemoglobinopathies and thalassemias?
hemoglobinopathies: qualitative defects of Hgb
thalassemias: quantitative defects of Hgb
what is the function of myoglobin, why don’t we use it as the main cardiac marker, and what is the significance of its increase?
carries oxygen from muscle cell membrane to mitochondria and serves as extra O2 reserve for longer exercise periods
Is the first cardiac marker to increase, but it decreases rapidly, so it’s not a good measure for heart conditions
increased in: striated muscle damage, myocardial infarction, rhabdomyolysis
what are porphyrias?
mutations of the porphyrins (which are made in the synthesis of heme)
can be erythropoietic or hepatic, and therefore affect the liver or RBC production
what does it mean that amino acids are amphoteric?
it means they have acidic and basic tendencies
what are the two NEGATIVE acute phase reactants?
albumin
transferrin (beta globulin)
