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BioFX
Casein Blocks and
Diluents |
This blocking is achieved through
blocking the test surface with inert
or irrelevant proteins. BioFX offers
several options for dilution and
blocking in multiple buffer
configurations. These formulations
offer scientists more flexibility
and a greater freedom of choice.
Bio FX Laboratories Buffered Casein
Blocks and Diluents are supplied as
concentrates. A typical blocking
agent would be an indifferent
macromolecule, large enough to
establish a stable attachment to a
surface, yet, small enough to find
its way between immuno-reactants.
The more heterogeneous casein is
often more effective. The high
blocking efficiency of casein is due
to its content of small molecular
weight proteins. Bovine Serum
Albumin, BSA, and Newborn Calf
Serum, NBCS, both contain relatively
large molecular weight components so
that random close-packing of these
molecules leave bare patches of the
unblocked surface.
BioFX Laboratories Casein
blocks and diluents are supplied as
concentrates. The high
blocking efficiency of casein is due
to its content of small molecular
weight proteins which are large
enough to establish a stable
attachment to a surface yet small
enough to attached between
immunoreactants.
BioFX Casein Buffers
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Borate Buffered Saline (BBS),
working pH range of 8.0 ±
0.2
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Borate Buffered Saline
(BBS)/Glycerol, working pH range
of 8.0 ± 0.2
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Imidazole Buffered Saline
(IBS), working pH range of 7.0 ±
0.1
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Tris Buffered Saline (TBS),
working pH range of 7.6 ±
0.1
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Phosphate Buffered Saline
(PBS), working pH range of 7.4 ±
0.1
BioFX Casein Powder
Notes Regarding Biological Buffers
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May specifically stimulate or
depress enzyme activity
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May interfere or react with
substrates, inhibitors or
cofactors
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Non-specifically they may
exert effects due to their ionic
strength
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Concentrations should be kept
as low as possible and maintain
pH constancy
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The medium should be adjusted
by adding appropriate inorganic
and organic ions to simulate
physiological conditions
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Borate Buffered Saline (BBS)
should not be used in the
presence of polyols, including
carbohydrates and their
derivatives with which they may chelate; BBS has a high
bacteriocidal effect; the use of
BBS in gel electrophoresis can
result in spreading of the bands
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Tris Buffered Saline (TBS),
pH 7.6, is a poor buffer below
pH 7.5 and the pH can fall more
than 1 pH unit in warming from 0°C
to 37°C;
TBS has the disadvantages of its
reactivity as a primary amine
and its appreciable solubility
in organic solvents which can
lead to an accumulation in the
biological phase of a reaction
system; to avoid complex
formation with ionic species
such as calcium and magnesium in
blood, Tris buffers are
preferable over phosphate
buffers
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Phosphate is a poor buffer
above pH 7.5; phosphate buffer
should not be used in assays
where competition for phosphate
groups, or complex formation
with a metal ion is essential
for the enzyme activation;
phosphate ions will inhibit
carboxypeptidiase, carboxylase,
urease, muscle diaminase,
formase and phosphoglucomutase
“It is
impossible even to guess how many
exploratory experiments have failed,
how many reaction rates have been
depressed and how many processes
have been distorted because of
imperfections of the buffers
employed.”
Norman Good, et al.
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