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For maximum reproducibility, the duration of each method step and the
time for sample application is measured in volthours. Volthours indicate
the extent of protein migration in the gel since electrophoretic mobility is
proportional to the applied voltage and the time that this voltage is
applied. Since the voltage change continually, the unit is equipped with
a volthour integrator, which integrates volts with time. The extra alarm
is also programmed in volthours. For more information about
volthours and volthour integration, see reference 1.
1. Isoelectric Focusing. In Gel Electrophoresis and Isoelectric
focusing of Proteins, Allen, R.C., Saravis, C.A., Maurer, H.R.
(editors), Walter de Gruyter, Berlin and New York, 1984, p. 76,
Allen R.C.
Cooling capacity
The cooling capacity of the separation bed will depend on the
following: 1) the ambient temperature; 2) the power applied to the
gels; and 3) if one or two gels are run. Fig. 4 below illustrates the
separation bed temperature versus time for native PAGE, SDS-PAGE,
and IEF runs. The running conditions are given in the caption under
the graph. A slight temperature drift can be seen for the IEF run with
an ambient temperature of 28°C. Even with an ambient temperature
of 38°C, no temperature drift is experienced with native gradient and
SDS-PAGE runs.
Fig. 4. Separation bed temperature vs time. The plots represent the following
conditions: l) IEF (PhastGel IEF 3-9); 2000 V 5 mA, 7 W 10°C, with 23°C ambient
temperature; 2) Same as 1) but with an ambient temperature of 28°C; and 3) Native
gradient SDS-PAGE (PhastGel gradient media); 400 V 15 mA, 4W 15°C; with ambient
temperature of 38°C.
3. Description of the system