6.3 Antigen Antibody Lec 6

Question 1

loops in antibody structure are connected by? important for?

Answer 1

disulfide bonds

• cysteine COVALENT bond
• important for structure

Question 2

What are the chains found in an antibody?

Answer 2

• 2 longer heavy chains that are EXACTLY the same

* 2 shorter light chains are exactly the same

Question 3

what are intrachain bonds?

Answer 3

disuldide bonds WITHIN a chain between areas called a domain

Question 4

what are interchain disulfide bonds for?

Answer 4

between or connect heavy chains

*usually 2! (can get 8-9)

Question 5

what connects heavy and light chains?

Answer 5

another disulfide bond (only one)

Question 6

what portion of antibody binds antigen? minimum amounts?

Answer 6

VARIABLE DOMAIN or “tip domain”

**minimum of 2 antigen binding sites

Question 7

what are the domains that do not bind antigen?

Answer 7

constant domain

Question 8

how many domains does the light and heavy chains have

Answer 8

• light= 2 (1 variable and 1 constant)

* heavy= 4 or 5 (1 variable and 3 or 4 constant domains)

Question 9

how big is each domain?

Answer 9

about 110 AA regardless of where is it or whether it is on heavy or light chain

Question 10

cystains (that create loop) on chains are always located in the same?

Answer 10

same spot

*evolutionary conserved system

Question 11

one antigen binding site is the result of one heavy chain variable region in close proximity to one light chain variable region- this is also called the ____ portion

Answer 11

Fab portion

Question 12

the constant regions of the heavy chain are important in binding to the neutrophil or macrophage to enhance phagocytosis. This is also called the ___ portion

Answer 12

Fc

Question 13

Fc portion is important for?

Answer 13

binding neutrophils or macrophages to enhance phagocytosis

Question 14

What are CDRs? what do they do?

Answer 14

complimentary determining regions that EVERY variable region of Ig has
*direct antigen binding site

Question 15

how many CDRs do domains of Ig’s have?

Answer 15

3

Question 16

where are variations of CDRs located?

Answer 16

3 in every domain

*around 32, 54, and 95

Question 17

do you need all 6 CDRs (3 from heavy and 3 from light) to make a functioning binding site?

Answer 17

yes

Question 18

Specific amino acids of light and heavy chain bind to antigen epitope how?

Answer 18

non-covalently

*but there is such HIGH affinity that the chances of dissociation are low

Question 19

affinity between antigen and antibody increases as?

Answer 19

with a better 3D fit

again, 3D conformation and AA sequence matters