Globins- Hb and immunoglobins

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