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transfer: amperes or volts?


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6 replies to this topic

#1 katenkak

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Posted 22 September 2010 - 03:52 AM

Hi all!
Apologize is my question is too naive, but I want to know whether is better to transfer proteins with constant amperes or constant volts? My colleagues tell that constant amperes are better, but I experience that when I set constant volts, I have a reproducible transfer, whereas with constant volts it is not. Moreover, when I attach two transfer tanks to the same power supply, amount of volts go down ca two times. Will transfer take twice as long than with only one transfer tank or...? Thank you for replies!

#2 protolder

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Posted 22 September 2010 - 05:15 AM

Hola, Itīs safer fix volts, because the power supply mantain them indepedent of the gels or tanks. Moreover fixing volts the amperage fall down during the transfer, but fixing mA the power supply needs increase volts to mantain mA and the transfer can boil if you donīt look after it. Good luck

#3 mdfenko

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Posted 22 September 2010 - 06:39 AM

it depends on your transfer method.

most semi-dry transfer units recommend fixed amperage while wet transfers units recommend fixed voltage.
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#4 Curtis

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Posted 22 September 2010 - 08:06 AM

mdfenko is right. most semi-dry blotters need fixed amperage. we keep voltage at 65 mA and volt at 15 V. immediately after start amperage reaches 65 but voltage starts from 3-4 and goes up to nearly 10 after one hour blotting.

to answer the 2nd question, my friends double our amperage if we want to run 2 blots in the same Biorad semi-dry blotter, but i never do that cause all my proteins transfer well to membrane at 65 mA anyway

Edited by Curtis, 22 September 2010 - 08:10 AM.


#5 katenkak

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Posted 22 September 2010 - 12:03 PM

Hi! Thanks for your answer. I run wet transfer today and encounted a problem with volts. I previously run transfer using home-made transfer buffer (actually 170mA to sustain ca 95 volts), but today in a hurry used NuPage transfer buffer and set constant 95 volts (it gave ca 110mA). My transfer was bad! Something like half of colored protein standard stayed in gel, whereas with home-made buffer my gels were clean. What was wrong and why transfer with the same amount of volts did not work? Thanks.

it depends on your transfer method.

most semi-dry transfer units recommend fixed amperage while wet transfers units recommend fixed voltage.



#6 katenkak

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Posted 22 September 2010 - 12:05 PM

What about wet transfer? My trasnfer is usually at 95V. I would be afraid running my western at 185...

mdfenko is right. most semi-dry blotters need fixed amperage. we keep voltage at 65 mA and volt at 15 V. immediately after start amperage reaches 65 but voltage starts from 3-4 and goes up to nearly 10 after one hour blotting.

to answer the 2nd question, my friends double our amperage if we want to run 2 blots in the same Biorad semi-dry blotter, but i never do that cause all my proteins transfer well to membrane at 65 mA anyway



#7 GNANA

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Posted 22 September 2010 - 01:56 PM

i usually transfer using home made TG(tris-Glycine)+methanol(20%).., i use 100 volt for 90 mins or 30mA overnight...i usually keep my transfer chamber in a ice filled basket or will run in cold room...also i precool my transfer buffer before running...i never had any problems with transfer...hope tis help..good luck.

Gnana..

Edited by GNANA, 22 September 2010 - 01:57 PM.

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