V (the first 4 digits of student ID) L = 2000L

7. Protein concentration and diafiltration Recombinant somatotropin is overproduced in E. coli in the form of intracellular protein inclusion bodies. After cell disruption and removal of other insoluble material, the homogenate is treated with a detergent to solubilize the somatotropin protein. The result is VL of solution ( V= the first 4 digits of student ID) containing 5%w/v somatotropin and 1.2%w/v detergent. Ultrafiltration is used in a twostep process to concentrate the somatotropin and wash out the detergent by diafiltration. The membrane has a 10,000-dalton molecular weight cut-off to achieve full retention of the somatotropin. The rejection coefficient for the detergent is zero. Hollow fiber modules are operated under gel polarization conditions to give a mass transfer coefficient of 2.2106ms1. The gelation concentration for somatotropin is 50%w/v. The effects of fouling can be neglected. (Tips: Membrane permeation rate = Flux Area) a) The somatotropin is concentrated by reducing the volume of the protein solution to 500L using batch ultrafiltration. The detergent is then removed by constant-volume diafiltration with buffer. (i) What membrane area is required if the batch concentration step must be completed within 2 hours? (ii) What volume of diafiltration buffer is required if the residual detergent concentration must be no greater than 0.002%w/v ? b) Instead of performing diafiltration after the protein concentration step as in a), diafiltration is carried out first. (i) What volume of buffer is required to reduce the detergent concentration to 0.002%w/v ? (ii) Compare the results of two cases and suggest a new way to optimize the operation. Any concern/constraint on your suggested way