[RASMB] fringe coefficient for RNA?

[Arthur Rowe]

Hi Gunther

'All' you need to know is the refractive index increment at the  
wavelength of the XL-I laser of your RNA - as compared to that of  
protein under the same conditions of wavelength, solvent, temperature,  
whatever. You will appreciate the significance of the first word in the  
last sentence!

Maybe someone has published something helpful, but the best I can offer  
is that Nieuwenhuysen et al (1981) Biochem J 197 689-693 give some  
results from their analysis of ribosomes which seem to show (this paper  
is a freebie on the web) that RNA has an increment of very roughly 6%  
less than that of protein. If that % difference holds at the (rather  
higher) wavelength where your interest lies, then in place of 1 fringe  
= 0.3019 mg/ml* you could use 0.32 mg/ml. Not exact - but neither is  
that figure for proteins.

Nieuwenhuysen et al also cite a paper in which the dn/dc value for an  
RNA is directly measured (Slegers et al, 1973 Biopolymers 12 2033-2044)  
- but you don't actually need to know an absolute value - just  
something relative to protein.

Regards

Arthur

*the final decimal bits should not be taken too seriously. individual  
proteins do differ.

On Sep 24, 2010, at 17:11, Kern, Gunther wrote:

> Hi,
>  
> I am looking for the fringe coefficient (fringes/(mg/ml) for RNA.
> Thanks a lot for your response,
>  
>  
> Gunther Kern
> Principal Scientist
> Molecular Biology
> AstraZeneca R&D Boston
> 35 Gatehouse Drive
> Waltham, MA02451
> Tel +1 781 839 4611
> gunther.h.kern at astrazeneca.com
>  
>  
>
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Arthur J Rowe
Professor of Biomolecular Technology / Director NCMH Business Centre
School of Biosciences
University of Nottingham
Sutton Bonington
Leics LE12 5RD

TEL:  0115 9516156
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