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T state
tense state; more interactions, more stable, lower affinity for oxygen
R state
relaxed state, fewer interactions, more flexible, higher affinity for oxygen
oxygen binding triggers a conformational change from _____ state to _______ state
T to R
what happens in the conformational change from T state to R state?
breaking of ion pairs between alpha 1 and beta 1 interface
what causes the puckered shape of the Hb T state?
His pulls on Fe
what causes the planar shape of Hb R state?
His and O2 pull on Fe
actively metabolizing tissues generate _____, _________ the pH of the blood near the tissues relative to the lungs
H+, lowering
what happens to H+ that is produced by metabolizing tissues?
it binds to Hb and stabilizes the T state
Hb affinity for oxygen depends on ___________.
pH
Bohr effect
pH difference between lungs and metabolic tissues increases efficiency of the O2 transport
how is 15-20% of CO2 produced by metabolism in tissues exported?
in the form of a carbamate on the amino terminal residues of each of the polypeptide subunits
how does the formation of carbamate contribute to the Bohr effect?
yields a proton
how does the formation of carbamate affect stability?
forms additional salt bridges, stabilizing the T state
2,3 BPG
negative heterotropic regulator of Hb function, small negatively charged molecule that binds to the positively charged central cavity of Hb; produced from an intermediate in glycolysis
affect of 2,3 BPG on O2 affinity
decreases affinity
affect of 2,3 BPG on stability
stabilizes T states
is sickle-cell anemia more likely when Hb strands are in T or R state?
T
in the absence of BPG, Hb is primarily present in the ____ state.
R
how does increasing CO2 affect the curve of O2 binding to hemoglobin?
shifts curve to the right
how does increasing H+ (decreasing pH) affect the curve of O2 binding to hemoglobin?
shifts curve to the right
how does increasing 2,3 BPG affect the curve of the O2 binding to hemoglobin?
shifts curve to the right
cellular immune system
targets own cells that have been infected, clears up virus particles and infecting bacteria
key players in cellular immune system
macrophages, killer T cells, inflammatory T cells
humoral “fluid” immune system
targets extracellular pathogens, can recognize foreign proteins and make soluble antibodies; keeps memory of past infections
key players in humoral immune system
B-lymphocytes and helper T-cells
antigens
substances that stimulate production of antibodies; typically macromolecular, recognized as foreign by the immune system, coat proteins of bacteria and viruses, surface carbohydrates of cells or viruses
antibodies
proteins produced by B cells that specifically bind to antigens
what happens when an antibody binds to an antigen?
antigen is marked for destruction or antibody interferes with antigen function
composition of Immunoglobulin G
2 heavy chains and 2 light chains, constant domains and variable domains
light chains
one constant and one variable domain
heavy chains
3 constant and one variable domain
which domains make up antigen-binding site?
variable domains
describe variable domains
hypervariable in amino acid sequence, specifically at antigen-binding site
how does variability affect specificity?
variability confers high antigen specificity
what does Fab stand for?
antigen-binding fragments
what does Fc do in immunoglobulin G?
interacts with Fc receptor on macrophage
describe secondary structure of immunoglobulin G
lots of beta sheets
what holds the subunits of immunoglobulin G together?
disulfide bonds
how many antigen binding sites are there per antibody?
2
effect of antigen binding on antibody
significant structural changes
