Hoefer TE 22, User Manual, Page: 18 / 34

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Final assembly and transfer
1
Install the lid
The cassettes are color coded to match the leads in
the lid. To transfer toward the anode, orient the lid so
that the grey half of the cassette faces the anode (+),
or red lead, and the black half of the cassette faces
the cathode (–), or black lead. Make sure the banana
plugs seat into the connectors in the lid.
2
Use only an approved power supply such as the
Hoefer PS 2A200. Make sure the power supply is off
and all controls are set to zero. Plug the color-coded
leads from the lid of the transfer unit into the power
supply — the red lead into the red output jack, and
the black lead into the black output jack. In most
systems, the red lead is the anode (+), and the black
lead is the cathode (–).
3
Cooling is strongly recommended
Any setting that results in higher than 5 W of power
will generate enough heat to require active heat
control. A refrigerated circulator bath using water
should be set to about 10 °C. (If using 50/50 ethyl-
ene glycol/water, the temperature can be set lower.)
Chill the buffer before use if possible.
Note: Take care in orienting the
lid so that all species migrate
toward the membrane when the
electric field is applied. The
migration direction depends on
both the characteristics of the
sample and the pH of the transfer
buffer. If the species of interest is
negatively charged in the transfer
buffer and the stack is assembled
so that the membrane is nearest
the grey side of the cassette, then
this side faces the anode (+). Most
proteins migrate toward the anode
in the Towbin Tris/glycine/metha-
nol buffer system (independent of
the presence of SDS), and under
most conditions, nucleic acids
are negatively charged and also
migrate toward the anode.
Important! Never allow the buffer
temperature to exceed 45 °C.
Excessive heat will cause the unit
to warp.
Typical transfer parameters
Parameters for your sample and buffer system
must be determined empirically.
protein nucleic acids
Buffer Towbin 1X TBE or 1X TAE
Current (A) 0.4 0.3
Voltage (V) ~100 50
Transfer time ~1 hour ~1 hour
Coolant temp. 10 °C 10 °C or less