Antibodies Flashcards
antibodies is also known as?
immunoglobulins
glycoproteins found in the serum portion of the blood, constitute approximately 20% of plasma
proteins in healthy individuals, composed of 86% to 98% polypeptide and 2% to 14% carbohydrate
immunoglobulins
play an essential role in antigen recognition and in biological activities related to the immune response such as opsonization and complement activation
immunoglobulins
immunoglobulins are divided into five major classes on the basis of a part of the molecule called the HEAVY chain, what are those five major classes?
IgG, IgM, IgA, IgD, and IgE
immunoglobulin constitutes approx. ____% of plasma proteins in healthy individuals
20
immunoglobulins are composed of __________%
polypeptide and _______% carbohydrate
86% to 98%
2% to 14%
immunoglobulin consists of two large chains called?
heavy or H chain
light or L chain (2)
each immunoglobulin chain has a SINGLE VARIABLE REGION (unique to each specific antibody) and ONE OR MORE CONSTANT regions
true
immunoglobulin chains are held together by ______ and _______ interchain bridges
non-covalent forces
disulfide
located at N terminus; unique to each specific antibody
variable region
with same amino sequence
constant region
cleaved IgG into 3 pieces
papain digestion
Fc fragment is known as
fragment crystallizable
spontaneously CRYSTALLIZED AT 4C, has NO ANTIGEN BINDING ABILITY, important in the EFFECTOR FUNCTIONS of Ig molecules (opsonization and complement fixation)
fragment crystallizable
2 identical Fab fragments is known as
fragment antigen binding
HAVE ANTIGEN-BINDING CAPACITY, consists of ONE L chain and ONE-HALF of an H chain held together by DISULFIDE bonding
fragment antigen binding
cleaved IgG at the CARBOXYL-TERMINAL side of the interchain double bonds; F(ab’)2 and Fc (similar to
Fc except that it disintegrated into several smaller pieces)
pepsin digestion
what are the two types of light chains
kappa chains and lambda chains
region with the same sequence (L chain)
constant region
amino-terminal end (L chain)
variable region
60% of L chains are ______ chains?
kappa
___% of L chains are Kappa chains because they are coded for first in DNA transcription of genes coding for antibody molecules
60
the difference between kappa and lambda chains lies in the ______ substitutions at a few locations along the chain
amino acid
there is no functional differences between the two types of light chains (kappa and lambda)
true
both types of L chain (kappa and lambda) are FOUND IN ALL FIVE CLASSES of immunoglobulins but ONLY ONE TYPE IS PRESENT IN GIVEN MOLECULE
true
in H chain, it is a location of the first approx. 110 amino acids at the AMINO-TERMINAL END
variable region
in H chain, it is a location of the remaining amino acids
constant region
in H chain, constant region can be divided into 3 or 4 constant regions with very similar sequences that is unique to each class and give each immunoglobulin type its name, what are these?
CH1, CH2, and CH3
has an γ H chain
IgG
has a μ chain
IgM
has an α chain
IgA
has a δ chain
IgD
has an ε chain
IgE
a unique amino acid sequence that is
common to all immunoglobulin molecules of a given class in a given species, determined by the heavy-chain constant region
isotype
there are five antibody isotypes that each have a unique heavy-chain constant region, enumerate.
IgG, IgM, IgA, IgD, and IgE
minor variations in isotype
allotypes
occur in the four IgG subclasses, in one IgA subclass, and in the κ L chain
allotypes
variable portions of each chain that are
unique to a specific antibody molecule, amino-terminal ends of both L and H chains serve as the ANTIGEN-RECOGNITION UNIT
idiotype
the segment of H chain located between the CH1 and CH2 regions
hinge region
hinge region has high content of ____ and HYDROPHOBIC RESIDUES
proline
chains that all have a hinge region
gamma, delta, and alpha
chains that has no hinge region
mu and epsilon
all types of immunoglobulins contain a CARBOHYDRATE PORTION, which is localized between the __________ domains of the two H chains
CH2
allows for flexibility
proline
lets the two antigen-binding sites operate independently and engage in an angular motion relative to each other and to the FC stem, assists in effector functions including initiation of the complement cascade and binding to cells with specific receptors for the Fc portion of the molecule
proline
increasing the solubility of immunoglobulin, providing protection against degradation, and enhancing functional activity of the FC domains
carbohydrate
predominant immunoglobulin in humans
IgG
IgG is _____% of total serum immunoglobulins
70-75
what is the half life of IgG
23 days
give the four major subclasses of IgG with its corresponding distribution
IgG1 - 66%
IgG2 - 23%
IgG3 - 7%
IgG4 - 4%