[RASMB] suggestion for improving analysis in case of high rmsd values and higher residuals near meniscus

[Toth IV, Ronald T]

Hi Prasad!

     Are you a new user? If not, apologies if these are obvious, and someone much more experienced than I can help you!

1) Unless you've loaded the cell perfectly (and who can!) you will have 2 meniscus artifacts, one for the sample and one for the reference. You might want to make sure you've set the meniscus at the sample meniscus and not the reference (it should be the positive spike).

2) If you are trying to fit right next to the meniscus, I would expect some high residuals there. However if you're trying to fit ~0.2 cm away from the meniscus and you're still getting residuals greater than 0.02 OD, then that is a problem!

3) The other main cause of high residuals is an incorrect frictional ratio. If you've already fit the frictional ratio, you might try fitting to a c(s,f/f0) distribution. If each species in your sample has a different frictional ratio, or if the frictional ratio isn't well determined, that could be a reason for your high residuals.

- Ronald Toth

Post Doctoral Researcher
Macromolecule and Vaccine Stabilization Center
University of Kansas
________________________________
From: rasmb-bounces at list.rasmb.org [rasmb-bounces at list.rasmb.org] on behalf of Prasad Satyamurthy [psatyamurthy at wockhardt.com]
Sent: Monday, March 10, 2014 6:53 AM
To: rasmb at rasmb.org
Subject: [RASMB] suggestion for improving analysis in case of high rmsd values and higher residuals near meniscus

Dear All,
             After I acquired Interference Data for my sample in my XLI Analytical Ultracentrifuge and fit using the continuous Cs model in sedfit I am not able to get good quality fit as indicated by a high rmsd values also the residuals close to the meniscus is high. Can anyone suggest me how can improve how to improve my analysis?

Thanks in Advance


Prasad Satyamurthy
Wockhardt Research Centre
Maharashtra India
Phone: +91 9987050315
Email: psatyamurthy at wockhardt.com

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