Bio-Rad’s PowerPac™ HC is one of the finest power supplies that we have ever dealt with. Its specifications include: 5–250 V, 0.01–3.0 A, 1–300 W, all fully adjustable. One can use it with constant voltage, current, or power; we predominantly use constant voltage. The PowerPac™ HC has completely replaced the PowerPac 200. It has 4 output jacks for simultaneous running of 4 identical electrophoretic units. It can be operated between 0 and 40oC, however, care must be taken when moving the instrument out of the cold room as the PowerPac can be damaged (because of condensation) if used immediately. A gap of at least 4 hours is preferable after removal from a cold room. It weighs 2 kg and so can be moved easily. Its programming is very simple. It has PFD (power failure detection) which can detect power failures; once power resumes, the unit will continue running until it has run for the required time. However, the PowerPac cannot differentiate between being turned off and a power failure. Therefore, if PFD is on, one should press the stop key and then switch it off. Because a rapid change in resistance may prove unsafe and may damage the PowerPac, the instrument also has a rapid resistance change detection system which shuts down the instrument if it senses a rapid change in resistance.
The LCD displays all parameters at once. It has a timer which helps you to run a gel for a specific time so that it does not over run. It is instrumental in blotting protein gels onto membranes as does not need to worry about looking at a watch or setting a separate timer.
We use the PowerPac™ HC for separation and blotting of proteins from rat and human tissue-derived cell lines. The PowerPac™ HC is compatible with all Bio-Rad apparatuses, including the Mini-PROTEAN® 3, Mini-PROTEAN® Dodeca™ gel and Mini Trans-Blot®. It is instrumental in blotting protein gels onto PVDF membranes as our local power supplies are not compatible with Bio-Rad transfer apparatuses (i.e. at times, local power supplies generate insufficient voltage). Transfer is really fast with the PowerPac™ HC and Bio-Rad’s transfer apparatus. With the aid of the Mini Trans-Blot®, we transfer proteins in an hour at a constant 100V with nearly 100% transfer. Larger gels (16X20 cm) are transferred efficiently in 3 hours at 60 constant volts. This transfer requires constant stirring (using a magnetic stirrer); without stirring, the transfer is not efficient. We also transferred 8 mini-gels in 2 cassettes of Bio-Rad’s Trans-Blot® (16X20 cm) and it proved very good in high throughput proteomics.
In conclusion, we have found the PowerPac™ HC excellent for our protein work. I don’t know if anything better can be made at this point of time.
Deepak Kanojia
Senior Research Fellow
Cancer Research Institute, Advanced Centre for Treatment, Research and Education in Cancer (ACTREC), TMC
Biochemistry and Cell Biology