Untitled - D Ank Unlimited

pepsinogen antibodies 564 peptidoglycolipid
one F(ab′) 2 fragment, which is bivalent and may manifest
many of the same antibody characteristics as intact IgG
molecules, such as antitoxic activity in neutralizing bacterial
toxins. Cleaving the Fc region from an IgG molecule
deprives it of its ability to fix complement and bind to Fc
receptors on cell surfaces. Pepsin digestion is useful in
diminishing the immunogenicity of antitoxins. It converts
them to F(ab′) 2 fragments that retain antitoxin activity.
pepsinogen antibodies
Antibodies against pepsinogen, which is produced by chief
cells and mucous neck cells. Autoantibodies against pepsinogen
develop in patients with autoimmune atrophic gastritis
with pernicious anemia. Three fourths of patients with
peptic ulcers have pepsinogen antibodies. Autoantibodies
are present in half of patients with pernicious anemia and a
quarter of patients with active duodenal ulcer.
peptide-binding cleft
Part of a major histocompatibility molecule that binds
peptides for display to T lymphocytes. Paired α helices on
a floor of an eight-stranded β-pleated sheet comprise the
cleft. Situated in and around this cleft are polymorphic
residues that are the amino acids that differ among various
MHC alleles.
peptide-binding motif
The assemblage of anchor residues of an MHC isoform
that are common to the peptide amino acid sequences that
interact with the isoform.
peptide interception
A possible cross presentation mechanism. An MHC class
II compartment holding exogenous peptides combines with
a vesicle-harboring MHC class I recycling from the cell
surface. A reduced pH in the MHC class II compartment
causes release of the endogenous peptide from the recycling
MHC class I molecule groove and permits loading of an
exogenous MHC class II compartment peptide, independent
of TAP, onto MHC class I.
peptide map
A fingerprint of peptides in two dimensions prepared by
digestion of a protein with an enzyme such as pepsin. Thin
layer chromatography in one direction and electrophoresis
Glc NAc
HO
CH 2 OH
OH
O
NAc
H
O
CH 3 C - CO
H
O
in the other direction at pH 6.5 yield the fingerprint
pattern.
peptide regurgitation
A possible mechanism of cross presentation. Following
internalization of extracellular proteins and processing
into peptides within dendritic cell endosomes, the
peptides are set free or “regurgitated” back into the
extracellular environment. The extracellular exogenous
peptide may negotiate an exchange of peptides at the cell
surface without intracellular processing. The exogenous
peptide displaces MHC-associated peptides displayed on
the surface.
peptidergic endothelium-derived contrasting factor (EDCF)
A unique 21-amino acid peptide with two intrachain disulfide
bonds. It is homologous to surafotoxin S6b. Also called
endothelin (ET). Four isoforms of ET and two ET receptor
subtypes have been described.
peptide T
A small HIV-1 envelope polypeptide initially believed to
have potential in treating AIDS, but later withdrawn.
peptide vaccine
An immunizing preparation comprised of a small antigenic
peptide capable of generating an immune response.
peptidoglycan layer
Humans have innate immunity against extracellular bacteria.
Neutrophil (PMN), monocyte, and tissue macrophage phagocytosis
leads to rapid microbicidal action against ingested
microbes from the extracellular environment. The capacity
of a microorganism to resist phagocytosis and digestion
in phagocytic cells is a principal feature of its virulence.
Complement activation represents a significant mechanism
for ridding the body of invading microorganisms. A peptidoglycan
layer in the cell walls of Gram-positive bacteria and
lipopolysaccharide (LPS) in the cell walls of Gram-negative
bacteria are able to activate the alternative pathway of
complement without antibody. Also associated with LPS are
flagellar antigen and somatic antigen.
peptidoglycolipid
A part of the wax D fraction extracted from mycobacteria
that contains the adjuvant principle in Freund’s adjuvant.
CH 2OH
CH 3
O
NCOCH 2 OH
H
L-Ala
OH
NHCHCO-NHCHCONH 2
Peptidoglycan (murein).
MA
CH 2
CH 2
D-Glu
CO-NHCH-CO-NHCHCOOH
CH 2
CH 2
CH 2
R-H N-C-CONH 2
H
MDP
D-Ala
CH 3
Meso-DAP