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Radius of the particle? Diffusion Problem 
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#1
Feb2310, 05:43 PM

P: 8

1. The problem statement, all variables and given/known data
One tool in analyzing proteins is gel diffusion. The technique is used to determine the size of the protein being analyzed. The following values are for diffusion through agarose gel. D (m2/s) Lysozyme 1.18E10 BSA 3.90E11 adolase 6.50E11 Cu2+ 1.00E10 glucose 2.90E10 insulin 4.60E10 The diffusion constant values are for the flux of particles, not change in concentration over time. Treating the diffusing particles as spheres moving through a liquid which presents resistance or “drag”, the diffusion constant can be related to the effective particle radius as D=kT/6πηR Where k is Boltzmann’s constant, η is the viscosity, T is the temperature in Kelvin and R is the radius. Using 20ºC as the temperature and the above diffusion constants for insulin and lysosyme, Calculate the effective radii of the two proteins. An appropriate value for the viscosity is 100 centipoise = 0.1 Pa•s. Do for Insulin and Lysozyme..... Or just one i did them but i am not sure my answer is correct the seem to high. 2. Relevant equations D=kT/6πηR 3. The attempt at a solution These are the answers i got when i attempted the solution. They seem to big though? Insulin i got R=1.9g x10^11 Lysozyme i got R=1.552 x 10^10 I just solved for R using the equation above 


#2
Feb2310, 06:01 PM

P: 8

I actually get 5.10x 10^12 for insulin
and 6.44x 10^11 for lysozyme The other answers were 1/R not R Is this correct because the are "effective"radius? 


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