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Old 10-12-2015, 08:24 AM   #165
jwfoley
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Location: Stanford

Join Date: Jun 2009
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Quote:
Originally Posted by Simone78 View Post
thatīs true, thanks for the explanation. I should have said "repackaged Superscript...with a twist" (changed few details to justify the new packaging)
Well, SuperScript II is wild-type MMLV RTase plus point mutations to kill the RNase H domain. In principle different companies could actually be selling different enzymes with different point mutations...

Quote:
Originally Posted by Simone78 View Post
However, nowadays most or all of the RT protocols around are done with some kind of MMLV-based enzyme and wonīt differ so much from each other. My opinion, at least.
Even the fancier enzymes like SuperScript III and Maxima are, as far as I can tell, just engineered to be heat-resistant. That's what makes them more processive: you could run SuperScript II at 50 °C and it would probably be just as fast, except the enzyme would degrade too quickly to be very useful. Unfortunately this engineering tends to kill the C-tailing activity for some reason. But if you aren't using template-switching, mere heat resistance is still a legitimate improvement. (For sequencing I might still worry about increased error rates at the higher temperatures.)
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