Radius of the particle? Diffusion Problem

Click For Summary
SUMMARY

The discussion focuses on calculating the effective radii of proteins, specifically insulin and lysozyme, using the diffusion constant values provided for each protein. The diffusion equation D = kT / (6πηR) is employed, where D represents the diffusion constant, k is Boltzmann's constant, η is viscosity, T is temperature, and R is the radius. The viscosity is set at 0.1 Pa·s, and the calculations yield R values of 5.10 x 10^-12 m for insulin and 6.44 x 10^-11 m for lysozyme, which are confirmed as correct effective radii.

PREREQUISITES
  • Understanding of diffusion constants in physics and chemistry
  • Familiarity with the equation D = kT / (6πηR)
  • Knowledge of Boltzmann's constant and its application
  • Basic concepts of protein structure and behavior in solutions
NEXT STEPS
  • Research the implications of protein size on biological function
  • Learn about the role of viscosity in diffusion processes
  • Explore advanced diffusion models in biophysics
  • Investigate other methods for determining protein size, such as size-exclusion chromatography
USEFUL FOR

Students and professionals in biochemistry, molecular biology, and biophysics who are involved in protein analysis and diffusion studies.

element41$
Messages
7
Reaction score
0

Homework Statement


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 1.18E-10
BSA 3.90E-11
adolase 6.50E-11
Cu2+ 1.00E-10
glucose 2.90E-10
insulin 4.60E-10
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.




Homework Equations



D=kT/6πηR

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
 
Physics news on Phys.org
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?
 

Similar threads

Average shear rate of of particle sureface
  • · Replies 12 ·
Replies
12
Views
2K
Application of Fick's First law (diffusion problem)
  • · Replies 3 ·
Replies
3
Views
11K
Calculating Diffusion Constant for Phosphatidylcholine in Water
  • · Replies 1 ·
Replies
1
Views
2K