[RASMB] Re: peculiar leakage problem!

[Dmitry Veprintsev]

Dear Sumit,
i apologise if it seems obvious:
we have to tighten our cells at the same temperature as the experiment 
(or lower). The centerpiece contracts more them the housing when cooled.
regards, Dmitry

sumit goswami wrote:
> For sure I put the cell inside the rotor with the holes facing towards 
> the axis of rotation. But I am not exactly sure if the leakage occured 
> through the feeling hole or between the centerpiece and windows. I 
> have seen spots of dried sample on the ouside surface of windows but I 
> don't remember seeing any circular line at the wall of the centrifuge 
> chamber. I have seen marks of leaked sample at the bottom of the rotor 
> where it supports the cell. So in my understanding it is very likely 
> that the leakage has occured between the windows and the centerprice. 
> One thing I must have to say is that our centerpices are old and they 
> might have some scratches or damages that are not clearly visible 
> through naked eyes. As Dr. Philo mentioned it might be that in 
> presence of protein the surface tension of the sample became low 
> enough to leak through the defects of the centeriece
>
> On Fri, Jun 12, 2009 at 4:51 PM, sumit goswami <ikant11 at gmail.com 
> <mailto:ikant11 at gmail.com>> wrote:
>
>     Dear all
>                 we have been trying do some sed-velocity experiments
>     for last couple of weeks but every time we tried most of the cell
>     assemblies leaked!! Apparently it seemed like a simple problem of
>     aging of center pieces but then very recently I ran all the seven
>     cell assemblies overnight at 50000rpm with water in them and none
>     leaked! After that I used the same set of assembly for running my
>     sample by sucking off the water from them  and 4 out of 5 leaked
>     even at 4000rpm. We have used different kinds of buffer so far...
>     PE (5mM Na-phosphate, 1mM EDTA), TE (10mM Tris, 1mM EDTA), Poly
>     buffer (MES,tris, acetate). All of our buffer had 0.01%PEG in
>     them. We have tried both PH 5 & 8.
>        Can anyone suggest what's going on? We are ready to buy new
>     centerpiece but not sure if that's the problem. The result with
>     water is confusing us!
>      
>     Thank you very much!
>      
>     Regards,
>     Sumit
>
>
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-- 
Dr. Dmitry Veprintsev
MRC Laboratory of Molecular Biology
Hills Road, Cambridge CB2 0QH, UK 
mailto:dbv at mrc-lmb.cam.ac.uk
Ph  +44 (0)1223 402027
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