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<TITLE>Re: [RASMB] Sedimentation coefficient of human serum albumin monomer and good protein standard with well established s value</TITLE>
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<BLOCKQUOTE>Greetings, everyone<BR>
<BR>
This issue is an obvious signal for a old hobby-horse of mine to have a run out in the field.<BR>
<BR>
The concept of a standard s value for some protein (or whatever) is a lovely idea. But two things are involved: one of them is getting suitable standard solute(s), which may be possible, say RNAse as one idea; but the the other thing is getting all the parameters to be either known or measurable. I have discussed in some detail all the factors which limit the precision and the accuracy of s values (Errington & Rowe 2003). The most serious matter by a way is the rotor temperature, and this is not known in the XL-I/A to the precision needed to take advantage of the precision inherent in the definition of s values by SV analysis.<BR>
<BR>
However, if you are prepared, or someone is, to check out the absolute temperature of a rotor using Walter Stafford's colorimetric method, then it just needs one definition of the 'real' s values for one or two well known, stable and monomeric proteins^ for everyone else to be able to benefit. Volunteers?<BR>
<BR>
Seasonal wishes to all<BR>
<BR>
Arthur<BR>
<BR>
^or something else, such as small colloidal gold spheres, from a batch available to all. They give beautiful SV diagrams. Or apoferritin - always has some dimers present, but they are resolved away, so who cares?<BR>
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Arthur J Rowe<BR>
Professor of Biomolecular Technology<BR>
NCMH Business Centre<BR>
University of Nottingham<BR>
School of Biosciences<BR>
Sutton Bonington<BR>
Leicestershire LE12 5RD UK<BR>
<BR>
Tel: +44 (0)115 951 6156<BR>
+44 (0)116 271 4502<BR>
Fax: +44 (0)115 951 6157<BR>
email: arthur.rowe@nottingham.ac.uk<BR>
Web: www.nottingham.ac.uk/ncmh/business<BR>
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<BLOCKQUOTE><BR>
N Errington, A J Rowe (2003) "Probing conformation and conformational change in proteins is optimally undertaken in relative mode" European Biophysics Journal 32 (5) 511-517<BR>
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<BLOCKQUOTE><TT><BR>
Hi! Everyone<BR>
We are looking for some "protein standard" to qualify our sedimentation<BR>
velocity method. We think that HSA may be a good candidate for the<BR>
standard. Does anyone know the sedimentation coefficient of human serum<BR>
albumin monomer (corrected for buffer density and viscosity as well as<BR>
vbar)? Some literatures said HSA has a sedimentation coefficient of 4.6 s,<BR>
this is significantly higher than the value of the monomer sedimentation<BR>
coefficient of HSA I got by analyzing the SV data of Sigma HSA using C(s)<BR>
model. The C(s) profile of this Sigma HSA showed that the product contains<BR>
about 80% monomer, 17% dimer and 3% trimer. So I guess the 4.6 s value<BR>
reported in some literatures is the weight average apparent s value of the<BR>
HSA monomer, dimer and trimer (or even some oligomers) in the sample<BR>
instead of the apparent s value of HSA monomer. Therefore it will be very<BR>
helpful for me if anyone can tell me the accurate s value of HSA monomer.<BR>
Also the suggestions for better protein standard (better commercial<BR>
available) with a well established s value will be very helpful.<BR>
<BR>
Thanks!<BR>
<BR>
Yiming<BR>
<BR>
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