[RASMB] determination of phage particle concentration

[Jo Butler]

Dear Sabine,

Carlos is correct in what he says, with the important error that it will 
be the nucleic acid which dominates the absorption, not the proteins, 
and any contaminating nucleic acid in the prep will lead to an overestimate.

Ultimately, any measurement of numbers will have been based on counting 
(as even DNA/RNA content is related to this at some stage); total 
numbers from e/m, infective numbers from a titre on a suitable bacterial 
lawn.

Jo

Carlos E. Catalano wrote:
> sabine,
> we have used the EM method to quantify total number of particles using 
> polystyrene beads as an internal standard.  you must titer to quantify 
> /infective/ particles, of course.  uv method will work fine, but 
> assumes that all of the absorbing species are actually proteins 
> incorporated into a viral particle (i.e., will also detect 
> partially-assembled structures).
> peter - the nanosight sounds interesting ...
> cec
> =========================================
> Carlos Enrique Catalano, Pharm.D., Ph.D.
> Professor of Medicinal Chemistry
> University of Washington School of Pharmacy
> 172H Health Science Building
> Box 357610
> Seattle, WA  98195-7610
> (206) 685-2468  (office)
> (206) 685-3252  (fax)
> catalanc at u.washington.edu <mailto:catalanc at u.washington.edu>
> http://depts.washington.edu/medchem/faculty/Catalano.html
>
>
>
>
>
>
> On Mar 4, 2010, at 2:57 AM, kaltofen at uni-potsdam.de 
> <mailto:kaltofen at uni-potsdam.de> wrote:
>
> Dear all,
>
> we are trying to obtain the concentration of bacteriophages in a 
> solution, concentration meaning the number of particles per ml. The 
> solution is supposed to be monodisperse and the MW is (roughly) known 
> but could be determined exactly. Is the any idea of how to do this 
> with a hydrodynamic method (staining is difficult to compare between 
> phage mutants and counting infected cells is tedious). I`ve got the 
> "feeling" that one could use the number-averaged MW, but maybe this is 
> totally wrong.
>
> Thank you for any hints, literature is also welcome.
>
> Cheers,
>
> Sabine
>
>
>
>
> Sabine Kaltofen
> PhD student
>
> Universität Potsdam
> Department of Physical Biochemistry
> Institute of Biochemistry and Biology
> Karl-Liebknecht-Str. 24-25, Haus 25, Raum B/0.05
> D-14476 Potsdam-Golm
> Telefon: +49-(331)-977-5245
> Email: kaltofen at uni-potsdam.de <mailto:kaltofen at uni-potsdam.de>
>
>
>
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-- 
Dr P.J.G. Butler,
MRC Laboratory of Molecular Biology,
Hills Road, Cambridge, CB2 0QH, UK.
Tel. +44 (0)1223 402296