Untitled - D Ank Unlimited

Fab′′ fragment 262 factor H
The Fab fragment is composed of one light chain and the variable and C H1 regions of a heavy chain. They are united by disulfide bonds and have a single
binding site for antigen. The heavy chain part of a Fab fragment is referred to as Fd. Further digestion with papain yields an Fc′.
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Pepsin
digestion
F(ab′) 2 fragment
A product of pepsin digestion of an immunoglobulin G
(IgG) molecule. This 95-kDa immunoglobulin fragment
has a valence or antigen-binding capacity of two that
renders it capable of inducing aggulination or precipitation
with homologous antigen. However, the functions associated
with the Fc region of the intact IgG molecule, such
as complement fixation and attachment to Fc receptors on
cell surfaces, are missing. Pepsin digestion occurs on the
carboxyl terminal side of the central disulfide bond at the
hinge region of the molecule which leaves the central disulfide
bond intact. The C H2 domain is converted to minute
peptides, yet the C H3 domain is left whole, and the two C H3
domains comprise the pFc′ fragment.
Fab′′ fragment
Refer to F(ab′) 2 fragment.
Fabc fragment
A 5-S intermediate fragment produced by partial digestion
of immunoglobulin G (IgG) by papain in which only
one Fab fragment is cleaved from the parent molecule in
the hinge region. This leaves the Fabc fragment, which is
composed of a Fab region bound covalently to an Fc region
and is functionally univalent.
Facb fragment
Abbreviation for fragment antigen and complement binding.
The action of plasmin on immunoglobulin G (IgG) molecules
denatured by acid cleaves C H3 domains from both heavy chain
Fd´
F(ab´) 2
F(ab′) 2 fragment containing 2 Fd′ heavy chain portions.
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Pepsin
digestion
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F(ab´) 2
Reduction
Pepsin digestion of an IgG molecule leading to formation of F(ab′) 2 intermediate fragments with reduction to the formation of Fab′ fragments.
Fab´
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Fab´
constituents of the Fc region. This yields a bivalent fragment
functionally capable of precipitation and agglutination with an
Fc remnant still capable of fixing complement.
FACS ®
Refer to fluorescence-activated cell sorter.
factor B
An alternative complement pathway component. It is a
739-amino-acid residue, single-polypeptide chain that
combines with C3b and is cleaved by factor D to produce
alternative pathway C3 convertase. Cleavage by factor D is
at an arginine–lysine bond at position 234 to 235 to yield
an amino terminal fragment Ba. The carboxyl-terminal
fragment termed Bb remains attached to C3b. C3bBb is C3
convertase, and C3bBb3b is C5 convertase of the alternative
complement pathway. The Bb fragment is the enzyme’s
active site. Factor B has three short homologous, 60-amino
acid residue repeats and four attachment sites for N-linked
oligosaccharides. Alleles for human factor B include BfS
and BfF. The factor B gene is located in the major histocompatibility
complex (MHC) situated on the short arm of
chromosome 6 in humans and on chromosome 17 in mice.
Also called C3 proactivator.
factor D
An alternative complement activation pathway serine
esterase. It splits factor B to produce Ba and Bb fragments.
It is also called C3 activator convertase.
factor D deficiency
An extremely rare genetic deficiency of factor D which has
an X-linked or autosomal-recessive pattern of inheritance.
The sera of affected patients contain only 1% of the physiologic
amounts of factor D, which renders them susceptible to
repeated infection by Neisseria microorganisms. The sera of
heterozygotes contain half the physiologic levels of factor D,
but they have no clinical symptoms related to this deficiency.
factor H
A regulator of complement in the blood under physiologic
conditions. Factor H is a glycoprotein in serum that unites
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