HW 9 - SP7 - Electrophoresis of BSA and Human Hemoglobin - 5 pts
A sample of bovine serum albumin (BSA) in solution was placed in a small electrophoretic cell. A laser anemometer measured its velocity as -1.4 x 10-3 cm/sec under the influence of an electric field of 10 V/cm. This experiment was repeated with a sample of human hemoglobin in solution and a velocity of -7.7 x 10-4 cm/sec was observed. Both samples were at 20oC.
a.) How much time is required to separate a mixture of BSA and human hemoglobin by gel electrophoresis ? An electric field of 4 V/cm is used and the initial band width of the mixture is 3 mm. Neglect diffusion. Assume the electrophoretic mobility of the proteins is unaffected by the presence of the gel.
b.) A Rayleigh light scattering experiment yields the diffusion coefficients of macromolecules. This experiment at 20oC yields the following results.
Do20,w (cm2/sec)
Bovine Serum Albumin
6.15 x 10-7
Human Hemoglobin
6.90 x 10-7
What is the charge number, z, of a molecule of BSA ? Human hemoglobin ?
Data: R = 8.314 g-cm2 / sec2-mole-K and F = 96487 coul/equiv
a.) How much time is required to separate a mixture of BSA and human hemoglobin by gel electrophoresis ? An electric field of 4 V/cm is used and the initial band width of the mixture is 3 mm. Neglect diffusion. Assume the electrophoretic mobility of the proteins is unaffected by the presence of the gel.
b.) A Rayleigh light scattering experiment yields the diffusion coefficients of macromolecules. This experiment at 20oC yields the following results.
Do20,w (cm2/sec)
Bovine Serum Albumin
6.15 x 10-7
Human Hemoglobin
6.90 x 10-7
What is the charge number, z, of a molecule of BSA ? Human hemoglobin ?
Data: R = 8.314 g-cm2 / sec2-mole-K and F = 96487 coul/equiv
posted by Dr. B at 8:38 AM
2 Comments:
does z have any units? when i solved for it, i was left with a [equiv](which means mol of e-???) in the numerator from the Faraday's value. this doesn't make sense if z is the charge.
Karen:
I am glad you asked, because it made me think about z some more.
z does have units. They are equivalents per mole (equiv/mole). That makes the units work out correctly. All of the , V, C, m, cm, g and kg get pretty messy, but I am pretty sure they will all work out. As a last resort, try using R = 8.314 V-C/mole-K and changing to SI (kg, m, s) and you will see that the units work out correctly.
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