Unit 3 - IV. Amino Acids and Proteins Flashcards
1
Q
Amino acid
A
- building blocks of protein
- only 20 out of > 700 A.A. are found in human proteins
- contains primary amine on one end and carboxylic acid group on the other
- have optical isomers/enantiomers (L vs. D)
2
Q
Zwitter ion
A
- internal acid-base reaction of amino acids cause H from COOH to transfer to nitrogen atom in amine group allowing A.A. to be dipolar
- Dipolar = both positive and negative charge in same molecule
3
Q
isoelectric pH
A
- isoelectric point
- the pH at which an amino acid exists in solution as a zwitterion
- depends on their classification (polarity) polar neutral/acidic/basic or nonpolar
4
Q
Dipeptide
A
- 2 amino acids
5
Q
Tripeptide
A
- 3 amino acids
6
Q
Polypeptide
A
- lots of amino acids (4-50)
7
Q
Peptide Bond Formation
A
- classified as a dehydration reaction
- consists of the functional group, amide
- peptide bond forms and water molecule is removed
8
Q
Nonpolar amino acids
A
- contain mostly hydrocarbon in their side chains
9
Q
Polar neutral amino acids
A
- contain either a hydroxyl group (-OH), a sulfhydryl group (-SH), or an amide group
10
Q
Polar acidic amino acids
A
- contain a carboxylic acid group
11
Q
Polar basic amino acids
A
- contain a primary or secondary amine group
12
Q
Glycine
A
- the simplest amino acid with a single hydrogen in the side chain
- doesn’t fit into any of the classification categories
13
Q
Contractile and Motile Role
A
- muscle contraction
Proteins involved: F-actin, nebulin, tropomyosin, troponin, and myosin
14
Q
Troponins
A
- Consist of three subunits: Tropoinin I, T, and C.
- subunits form a complex with actin and tropomyosin to create a large series of interconnected molecules that are responsible for muscle contraction
- Troponin T can be measured to find MI and is just as good as measuring Troponin I
15
Q
cTnI
A
- cardiac troponin I
- Regulates striated muscle contraction.
- Has three isoforms.
- Cardiac form of cTnI is never expressed in skeletal muscle.
16
Q
cTnT
A
- cardiac troponin T
- Binds to tropomyosin.
- Has three isoforms: skeletal (slow-and fast-twitch) and cardiac muscle.
- In fetal development, the cardiac and skeletal forms are co expressed in both skeletal and cardiac tissues.
17
Q
Structural Role
A
Proteins involved: elastin, collagen, keratin
- elastin = resilience and ability to be stretched
- collagen = strength
- keratin = stability (insoluble)
18
Q
Storage role
A
- “vaults” where substances can be stored until needed
Proteins involved: Ferritin (iron), Casein (milk protein), ovalbumin (egg white protein)
19
Q
Transportational role
A
- carry other substances around the body Protein involved: - Hemoglobin (oxygen through blood) - myoglobin (oxygen through muscles) - serum albumin (Fatty acids through blood) - transferrin (iron) - ceruloplasmin (cooper)
20
Q
Regulatory role
A
Proteins involved:
- insulin (induce up take of glucose into cells)
- somatotropin (growth hormone)
21
Q
Protective role
A
Proteins involved:
- thrombin and fibrinogen (coagulation)
- survivin (inhibits apoptosis)
22
Q
Primary Structure
A
- sequence of amino acids in a protein (kind, #, and order)
23
Q
Significance of Insulin’s primary structure
A
- the first protein to have its amino acid sequence deciphered
- showed that the same protein in different species can be very similar
- insulin from porcine and bovine were used by diabetics but over time the body would react immunologically against it
24
Q
Significance of Hemoglobin’s primary structure
A
- showed that a substitution of 1 a.a. can cause a protein to malfunction (ex. sickle cell)
25
Q
Secondary structure
A
- the special alignment of atoms in the backbone due to hydrogen bonding between the C=O of one peptide and N-H of another 3 Types: - Alpha helix ( same chain) - Beta pleated sheet (2 chains) - Triple helix ( 3 chains)
26
Q
Tertiary structure
A
- three dimensional shape as a result of folding and bonds from several types of bonding.
Types of bonding: - Salt bridge = basic side chain + acidic side chain
- disulfide bonds = two cysteine side chains
- hydrophobic interactions = nonpolar side chains in polar environment
- hydrogen bonds = two polar neutral or polar neutral + polar charged
27
Q
Quaternary structure
A
- the number of subunits (polypeptide chains) and how they are held together (hydrogen bonds, salt bridges, and hydrophobic interactions)
28
Q
Denaturation
A
- the disruption of the secondary, tertiary, and quaternary structures of a protein
= results in loss of biological activity - primary structure remains intact
- irreversible
Types: Heat, pH effects, heavy metal salts, organic solvent, food enzymes
29
Q
Heat
A
- disrupt hydrogen bonds and hydrophobic interactions
+ heat = rupture peptide bonds - Example: heating eggs
30
Q
pH effects
A
- disrupt hydrogen bonds and salt bridges resulting in coagulation
- Example: acid + milk = casein (milk protein) or adding KOH to eggs
31
Q
Heavy metal salts
A
- disrupt salt bridges and covalent disulfide bonds
- Example: silver nitrate added to eggs
32
Q
Organic solvents
A
- form hydrogen bonds = compete with naturally occurring hydrogen bonds
- used as (alcohol) disinfectants because it denatures and coagulates protein in bacterial cell walls
- Example: 2-propanol added to eggs
33
Q
Food enzymes
A
- hydrolyze peptide bonds disrupting primary structure (and therefore 2, 3, and 4 structures)
- example: meat tenderizer (papain from papaya) or pineapple (bromelain) added to eggs
34
Q
C-reactive protein (CRP)
A
- positive acute-phase reactant protein synthesized in liver
- elevated in inflammation, infection or injury
- CRP test used to monitor wound healing, surgical incisions, organ transplants, burns, and early detection of infection
- predictor (not diagnostic) of atherosclerosis because inflammation can be caused by coronary vessel pathogens, myocardial necrosis/ischemia etc.
- CRP presence in arterial wall predicts severity of atherosclerosis
35
Q
Hs-CRP
A
- high sensitivity C-reative protein
- test assesses the connection between high CRP levels and risk of cardiovascular disease (detects small amounts of CRP to evaluate CV risk)
36
Q
Total protein
A
- 3 components: Prealbumin, albumin, and globulin
- Total protein = albumin + globulin
- used to monitor liver disease, kidney disease, malnutrition, and chronic edema
- serum protein electrophoresis = 5 bands (- gamma, beta, alpha 2 , alpha 1, albumin +)
37
Q
Prealbumin
A
- transports thyroxine and vitamine A
- has a short half life (2 days) and can be used to monitor patients nutritional status
- increase during pregnancy, chronic kidney disease, nephrotic syndrome, and hodgkins status
- decrease during liver diseases, malnutrition, and acute inflammation
38
Q
albumin
A
- most abundant plasma protein
- synthesized in liver
- helps maintain oncotic pressure which pulls water into the circulatory system
- also transports vitamin B6, Zn 2+, Ca 2+, fatty acids, drugs, and hormones
- increases during dehydration
- decreases malnutrition and various liver disease
39
Q
globulins
A
- increase during acute/chronic infections/inflammation, cirrhosis of liver, and various malignancies (ex: hodgkin’s, leukemia, lymphomas)
- decrease malnutrition, wilson’s disease
3 types: alpha, beta, gamma
alpha globulins = alpha1, antitrypsin, ceruloplasmin, cholinesterase, and prothrombin
beta globulins = complement proteins, fibrinogen, plasminogen, and transferrin
gamma globulins = antibodies
40
Q
alpha 1-antitrypsin
A
- antiprotease activity against chymotrypsin, kallikrein, renin, and plasmin
- increase in inflammatory disease
- decrease in lung and liver disease
41
Q
ceruloplasmin
A
- copper containing protein
- functions in redox reactions
- regulates the ionic state of iron and its incorporation into transferrin
- increases in APR (late reacting) and by estrogen
- decreases inWilson disease (hepatolenticular degeneration) where copper deposits into tissue (of liver and eye)
42
Q
Transferrin
A
- plasma transport protein of the iron
- synthesized in liver
- useful for differential diagnosis of anemia and monitoring treatment of anemia
- increase in iron deficiency
43
Q
Natriuretic peptides
A
- majority are cardiac peptides
- increase after MI, chronic Hypertension, CHF
- includes ANP (arterial) and BNP (brain)
44
Q
BNP
A
- B type natriuretic peptide
- Dilate blood vessels
- Increase the excretion of sodium and fluids
- Reduce concentrations of neurohormones that lead to: Vessel constriction, Fluid retention, Elevated blood pressure
- increases with CHF
- used to distinguish shortness of breath due to CHF (normal with other pulmonary causes)
45
Q
Cytokines
A
- proteins that play a role in intercellular signalling
- 5 categories that have functions that overlap:
1. interferons
2. interleukins
3. chemokines
4. colony-stimulation factor
5. tumor necrosis factor (TNF)
46
Q
Homocysteine
A
- sulphur containing amino acid produced via remethylation and transsulfuration of methionine (SAM)
47
Q
Hyperhomocysteinemia
A
- caused by folate deficiency, enzyme deficiencies and a variety of drugs, solvents, toxins
- risk factors include physiologic, genetic, clinical conditions, and life style
48
Q
Myoglobin
A
- complex oxygen binding protein present in cardiac/skeletal muscle
- excreted in urine
- nephrotoxic
- useful for early detection of MI (3 hrs) but is cleared rapidly and has lower specificity
