BioHPLC Column Selection Guide Cover - Agilent Technologies

dimer
A polymer made up of two identical molecules. When three molecules
link up, the resultant polymer is called a trimer. Larger polymers are
usually referred to by placing a number before the "-mer" suffix: 4-mer,
5-mer, 6-mer, and so on.
disulfide bond
A covalent bond formed between sulfur atoms of different cysteines in
a protein; such bonds (links, bridges) help hold proteins together.
DNA
Deoxyribonucleic acid, the nucleic acid based on deoxyribose (a sugar)
and the nucleotides G, A, T, and C. Double-stranded DNA has a
corkscrew-ladder shape (the Double helix") and is the primary
component of chromosomes, which thus carry inheritable
characteristics of life. See nucleotides and nucleic acids.
drug substance
(or active pharmaceutical ingredient); the active drug chemical or
biological substance in purified bulk form. The drug substance is further
processed to derive a drug product.
E
efficacy
The ability of a substance (such as a protein therapeutic) to produce a
desired clinical effect; its strength and effectiveness; usefulness; the
power to produce an effect.
enzymes
Proteins that catalyze biochemical reactions by causing or speeding up
reactions without being changed in the process themselves.
epitope
A molecular region on the surface of an antigen that elicits an immune
response and can combine with the specific antibody produced by such
a response; also called a determinant or an antigenic determinant.
excipient
A type of raw material that is present in the drug product and thus has
direct patient contact; includes inert materials such as bulking agents,
stabilizing agents, preservatives, salts, solvents or water. An excipient
must be evaluated for safety in animals, unless it has been approved as
GRAS or is on a list of approved excipients.
Appendices
express
To translate a cell's genetic information, stored in its DNA (gene), into a
specific protein.
expression system
A host organism combined with a genetic vector (such as a virus
or circular DNA molecule called a plasmid) that is loaded with a gene
of interest. The expression system provides the genetic context in which
a gene will function in the cell - that is, the gene will be expressed as
a protein.
expression vector
A virus, plasmid, cosmid, or artificial chromosome that delivers foreign
genes to a host, creating a recombinant organism that will express the
desired protein.
F
Fab
Antigen-binding fragment of an immunoglobulin. An IgG Fab is
prepared by enzymatic cleavage of the intact tetrameric IgG, and
reduction of the inter-chain disulfide links, and binds one mole of
antigen per mole. See F(ab)'2.
F(ab)'2
Dimeric antigen-binding fragment of an immunoglobulin. An IgG F(ab)'2
is prepared by enzymatic digestion of an intact IgG, which removes the
Fc portion of the molecule. F(ab)'2 binds two moles of antigen per
mole. See Fab.
FAb
Antibodies are Y-shaped molecules. The "arms" of each Y are the FAb
regions (fragment antigen binding sites) that bind to antigens; the stem
of the Y is the Fc region, which attracts microbe-engulfing cells to
destroy what has been bound. If the active part of an antibody can be
identified, sometimes only that part of it may be needed as a
therapeutic molecule (facilitating production and processing by reducing
the size and lessening the chances of an immune response in patients
who receive the drug). This fragment may be "conjugated" to another
molecule (such as PEG) for stability or other reasons.
Fc
Portion of an immunoglobulin molecule that carries various effector
functions, such as the ability to bind complement. Important in
immunological activities, and separable from the antigen-binding
portion by enzymatic or chemical cleavage. See Fab.
APPENDICES
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