immunoglobulin

Question 1

immunoglobulin

Answer 1

term given to certain blood proteins that are involved in immunity. these are proteins (often referred to as antibodies) that can react with foreign molecules (antigens)

Question 2

blood proteins contain which principle types of proteins

Answer 2

albumins- proteins soluble in water and which are precipitated by full saturation with ammonium sulphate
Globulins-Less soluble proteins which are precipitated by half saturation with ammonium sulphate

Question 3

antibodies two main functions

Answer 3

• binding foreign antigens encountered by the host

- mediating effector functions to neutralise or eliminate foreign invaders

Question 4

IgG-Primary, secondary, tertiary and quaternary structure

Answer 4

IgG is the most common immunoglobin
Primary-sequence of amino acids (light and heavy chains)
Secondary structure-folding of each polypeptide chain upon itself to form a series of beta pleated sheets
Tertiary structure-each chain is folded into compact globular domains
Quaternary structure- chains interact to from functional molecule

Question 5

IgG structure

Answer 5

-IgG is the major Immunoglobin class in serum
-IgG is a heterodimer
there is disulphide bonds in the hinge region and in between the light and heavy chain . This allows the molecule to be held together as well as a degree of flexibility
intrachain disulphide bond forms a loop of about 60 aa in each domain
This helps to sustain tertiary and quaternary structure (3D structure) -intra-chain disulphide bonds
there is light chains and heavy chains
the hinge region keeps together the two identical sides of the same molecule
The light and heavy chain are broken into the variable region and the constant region. The antigen binds at the variable region. there is 3 Complementary determining (hypervariable) regions CDRs on each of the variable regions . it is the combination of variability of the 3 CDRs that forms the basis of variation of binding.

Question 6

antigen binding sites

Answer 6

• IgG has two identical antigen binding sites
• each binding site is made up of 6 CDR regions (3 from light chain and 3 from heavy chain)
• This complexity allows >10 million different antigen binding sites
• most CDRs contribute to antigen binding

Question 7

What do antibodies bind to

Answer 7

Antibodies can distinguish differences in the primary structure of the antigen as well as the secondary and tertiary as well as isomeric forms of the antigen

Question 8

antigenic determinant

Answer 8

(epitope)The portion of the antigen which binds to the antigen binding site of the antibody

Question 9

Immunoglobin Fragment functions

Answer 9

Fab region- antigen binding

Fc region- Effector functions -binding to Ab or Ag mediates biological effects via the Fc fragments