Bio-Rad Mini-PROTEAN® Tetra Cell - Manual (Page 33)

29
Troubleshooting Guide (cont.)
Problem Cause Solution
Lanes constricted at
the bottom of the gel
Ionic strength of
sample higher than
the surrounding gel
Desalt sample and neighboring
samples
Run taking unusually
long
Running buffer too
concentrated
Excessive salt in
sample
Check buffer protocol, dilute if
necessary
Desalt sample
Run too fast Running or reservoir
buffer too dilute
Voltage too high
Check buffer protocol, dilute if
necessary
Decrease voltage by 25–58%
Doublets observed
where single protein
species is expected
(SDS-PAGE)
A portion of the
protein may have
been reoxidized
during the run or
may not have been
fully reduced prior to
the run
Prepare fresh sample buffer
solution if over 30 days old;
increase concentration in the
sample buffer; sustitute DTT for
BME
Fewer bands than
expected and one
heavy band at the
dry front
Protein(s) migrating
at the dye front
Protein degradation
Increase the %T of the resolving
gel*
Use protease inhibitors, e.g.,
PMSF, etc.
Upper buffer
chnamber leaks
Upper buffer
chamber overfilled
Improper assembly
Keep buffer level below the top of
the spacer plate
Be sure U-shaped electrode core
gasket is clean, free of cuts, and
lubricated with buffer
Be sure short plate is under the
notch on the gasket, not on top
of it
Leaking during hand
casting
Chipped glass plates
Spacer plate and
short plate not level
Csating stand gasket
is dirty, flawed, or
worn out.
Ensure glass plates are free of
flaws
Ensure plates are aligned
correctly
Wash the gasket if it is dirty,
replace casting stand gaskets if
flawed or worn out