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fluorescence treponemal antibody test 279 fluorescent protein tracing
Fluorescence (arbitrary units)
Antidichlorofluorescein
10,000 Antibody
8000
6000
4000
2000
0
0
Quenching of fluorescein ( ) and
dichlorofluorescein ( ) fluorescence by homologous
and cross-reacting rabbit antibody.
Dichloro-fluorescein ( ) and fluorescein fluorescence ( ) in
buffer alone are shown in the left-hand figure.
energy transfer by which certain electronically excited residues
in protein molecules such as tryptophan and tyrosine
transfer energy to a second molecule bound to the protein.
Maximum emission is a wavelength of approximately 345
nm. The attachment of the acceptor molecule need not be
covalent. This transfer of energy occurs when the absorbance
spectrum of the acceptor molecule overlaps that of
the emission spectrum of the donor and takes place via
resonance interaction. The two molecules need not contact
directly for energy transfer. If the acceptor molecule is
nonfluorescent, diminution of energy occurs through nonradiation
processes. Conversely, if the acceptor molecule
is fluorescent, the transfer of radiation to it results in its
own fluorescence (sensitized fluorescence). Fluorescence
quenching techniques can provide very sensitive quantitative
data on antibody–hapten interactions.
fluorescence treponemal antibody test
Refer to FTA–ABS test.
H 5 C 2
H 5 C 2
N
50 100 0
Hapten added (µµ moles)
O N
Antifluorescein
Antibody
COOH
C2H5 C2H5 Rhodamine B isothiocyanate is a reddish-orange fluorochrome used to label
immunoglobulins or other proteins for use in immunofluorescence studies.
50
100
Titration curves using fluorescence quenching.
(C 2H 5) 2N
SO – 3
SO – 3
Fluorescent antibody technique.
fluorescent antibody
An antibody molecule to which a fluorochrome such as
fluorescein isothiocyanate has been conjugated.
fluorescent antibody technique
An immunofluorescence method in which antibody labeled
with a fluorochrome such as fluorescein isothiocyanate (FITC)
is used to identify antigen in tissues or cells when examined by
ultraviolet light used in fluorescence microscopy. In addition
to the direct technique, antigens in tissue sections treated with
unlabeled antibody can be counterstained with fluoresceinlabeled
antiimmunoglobulin to localize antigen in tissues by the
indirect immunofluorescence method.
fluorescence in situ hybridization (FISH)
A technique in which whole cells or a chromosomal spread
on a microscope slide are exposed to a fluorescently labeled
DNA probe. Subsequent microscopic examination of the
whole chromosome or a specific part may reveal tumorigenic
chromosomal translocations that are clearly visible
by this technique. Multiple probes tagged with separate
fluorochromes may be used simultaneously.
fluorescent protein tracing
Fluorescent dyes are used in place of nonfluorescent dyes
because they are detectable in much lower concentrations.
O
N + (C 2H 5) 2
Rhodamine disulfonic acid is a red fluorochrome used in
immunofluorescence.
H 5 C 2 N +
O
SO – 3
SO 3 Na
NC 2 H 5
Lissamine rhodamine (RB200) is a fluorochrome that produces
orange fluorescence. Interaction with phosphorus pentachloride
yields a reactive sulfonyl chloride that is useful for labeling protein
molecules to be used in immunofluorescence staining.
Direct
Indirect
Sandwich
Complement
F