6 Protein centrifugalion Proteins and other macromolecules can be separated by size using centrifugation. The idea is to spin a sample con- taining...

Please address the attached problem regarding protein centrifugation

12.6 Protein centrifugalion Proteins and other macromolecules can be separated bysize using centrifugation. The idea is to spin a sample con-taining proteins of different size in solution. The spinningproduces a centrifugal force per unit mass gc, which leadsto diffusion with a drift velocity that depends on the pro-tein size. We assume that a protein in the sample can beapproximated as a ball of radius R. (a) Following the discussion in the chapter fill in the stepsleading up to the formula for the drift velocity of theprotein as a function of its radius (eqn 12.45). 2(Pprotein — Prolvenr)gc R2Vdriff = 9n ' where ppmmm and pmlvem are the densities of the proteinand the solvent, and n is the solvent viscosity. (b) Estimate the drift velocity for hemoglobin in water_in an ultracentrifuge with gc 2: 1059, where 9% lOm/s2is the acceleration of freely falling objects in Earth'sgravitational field. Assume a typical protein density of1.2 g/cm3. (c) We would like to separate two similar proteins. havingthe same density. p’ = 1.35 g/cm3. They have diameters of4 nm and 5 nm respectively. The two protein species startout mixed together in a thin layer at the top of a 1 cm longcentrifuge tube. How large should the centrifuge acceler-ation gc be so that the two proteins are separated beforethey drift to the end of the tube?