Exam 2 Biochemistry: immunoglobins
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39 Terms
A ligand binds to a protein at a binding site that is _______ to the ligand in…
complementary
size, shape, charge, and hydrophobic or hydrophilic character
what is an immune response
coordinated set of instructions among many classes of proteins, molecules, and cell types
what does an immune response entail
distinguishes molecular “self” from “nonself” and destroys “nonself”
eliminates viruses, bacteria, and other pathogens and molecules
what are leukocytes
examples of leukocytes
white blood cells
macrophages and lymphocytes
the immune response consists of two complementary systems:
humoral immune system
cellular immune system
what is the humoral immune system
it is directed at bacterial infections and extracellular viruses
what is the cellular immune system
destroys infected host cells, parasites, and foreign tissues
In the Humoral immune response:
antibodies = ______________ = ….
immunoglobulins (Ig)
binds bacteria, viruses, or large molecules identified as foreign and target them for destruction
immunoglobulins are produced by…
B lymphocytes or B cells
In the Cellular Immune Response:
T lymphocytes (T cells) include:
cytotoxic T cells (Tc cells)
helper T cells (TH cells)
memory cells
what is the function of cytotoxic T cells
recognition of infected cells or parasites involves T-cell receptors on the surface of Tc cells
what is the function of helper T cells
they produce soluble signaling proteins called cytokines that
interact with macrophages and
stimulate the selective proliferation of TC and B cells that can bind to a particular antigen
what is clonal selection
when helper T cells stimulate the selective proliferation of TC and B cells that can bind to a particular antigen
what is the function of memory cells
the permit a rapid response to pathogens previously encountered
The functions of many proteins involve the ____________________ of other molecules (called _________)
reversible binding
ligands
what is an antigen
a molecule or pathogen capable of eliciting an immune response
An antigen can be…
it can be a virus, a bacterial cell wall, or an individual protein or other macromolecule
antibodies or T-cell receptors bind to ____________ or __________ within the antigen
antigenic determinant
epitope
what are haptens
small molecules that can elicit an immune response when covalently attaches to large proteins
Antibodies have two identical ___________
antigen-binding sites
what is Immunoglobulin G (IgG)
a major class of antibodies
what antibody is one of the most abundant blood serum proteins
IgG
what does IgG consist of
4 polypeptide chains: 2 heavy and 2 light chains
cleavage of IgG with protease papain releases…
the basal fragment Fc and two Fab branches (each with a single antigen binding site)
IgG constant domains contain…
the immunoglobulin fold structural motif
The molecular structure for which an individual antibody or T-cell receptor is specific is known as:
an epitope - a particular molecular structure within the antigen
Structure of immunoglobulin G (IgG)
Y shaped
Variable domain of IgG is present on…
each light and heavy chains
what do the variable domains of IgG do
variable domains associate to create the antigen-binding site
they allow the formation of an antigen-antibody complex
Phagocytosis of antibody-bound viruses by macrophages occur when
when Fc receptors bind an antibody pathogen complex, macrophages engulf the complex
Antibodies bind ________ and _________ to antigen
tightly
specifically
what is induced fit
conformational changes in the antibody and/or antigen allow the complementary groups to interact fully
antibody-antigen binding has Kd values…
as low as 10-10M
The antibody-antigen interaction is the basis for a variety of important _____________________
analytical procedures
what are the two types of antibody preparations used
polyclonal antibodies
monoclonal antibodies
what are polyclonal antibodies and how are they produced
produced by injecting a protein into an animal
contain a mixture of antibodies that recognize different parts of the protein
what are monoclonal antibodies and how are they produced
synthesized by a population of identical B cells (a clone)
homogenous, all recognizing the same epitope
Immunoblot = _____________ = ?
Western blot assay
uses antibodies (polyclonal) to detect a protein
lower Kd values = _________ affinity
higher