Explain the function of antibodies and describe their structural and chemical characteristics.
- •Antibody (Ab): Proteins made in
- response to an Ag; can combine with that Ag.
- •Also called immunoglobulin or antitoxin
•Proteinaceous molecules that bind antigens at the antigen-binding site (unique location to the specific receptor).
•Each is made of two heavy
and two light chains
of amino acids, held together by disulfide bonds
- Made up of variable (meaning they change..the difference has to do with the shapes of the arms)and constant regions (the constant Y shape).
- -parts of the antibody (Ab) are constant, i.e., the same for every antibody
- -parts are variable - the arms of the “Y” have different amino acid sequences that cause specific binding to antigen
•the fact that there are many different variable regions results in antibodies that react with almost any antigen you could possibly encounter!
- How they work:
- •Some act as opsonins, and adhere to microbes to identify antigens for phagocytes and stimulate phagocytosis.
•Some work by neutralization
(i.e. they neutralize toxins for e.g. those causing diphtheria and tetanus) by binding to the toxin to neutralize it so it cant work
•Some cause agglutination
(clumping together) of bacteria making them less likely to spread