[RASMB] varying temperature during an equilibrium run

John J. Correia jcorreia at umc.edu
Fri Oct 25 08:16:59 PDT 2013


Frank, if you think the association is weaker at higher temp then the relaxation will be primarily by diffusion if you go low to high temp. This will cause a very slow equilibration time. I suggest doing high to low temp in your case.  Our experience is that over a broad range of temp (5 to 20 to 30C) the time to equil is about the same if the system doesn't change much at each temperature.

From: Frank Niesen <dr.frank.niesen at gmail.com<mailto:dr.frank.niesen at gmail.com>>
Date: Friday, October 25, 2013 9:47 AM
To: "rasmb at rasmb.org<mailto:rasmb at rasmb.org>" <rasmb at rasmb.org<mailto:rasmb at rasmb.org>>
Subject: [RASMB] varying temperature during an equilibrium run

Hello,

I was wondering if anybody has experience with changing the temperature in an equilibrium run at given speed, to investigate temperature-dependent strength in association? Is it feasible/sane to record data at equilibrium at, e.g., 20C, and then to change the temperature to, e.g., 40C, and to hope to get data for equilibrium and record once more?

In my case, the association seems to weaken substantially with temperature and I observe a weaker curvature at the higher temperature. For a third step, going back to the original temperature, I programmed the run, but made two mistakes with it - firstly to not allow sufficient time for the equilibrium and, secondly, to somehow got the "stop AUC after last scan" checked :o(
As result, I am looking at a scan that doesn't resemble the one at lower temperature, yet it is similar to scans I saw during the equilibration between the two temperatures at step 2.

Has anybody tried something similar? Am I onto something believable/real, or shouldn't waste any more precious sample on a proper repeat (i.e. separate runs/samples for each temperature)?

Thanks in advance!
Frank
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