Protein D consists of 120 residues and forms a dimer through…
Protein D consists of 120 residues and forms a dimer through an α-helix at the very C-terminus (residues 100-120). The dimer recognizes a specific 9-base pair DNA sequence. You are purifying the protein in order to determine its structure. A) For the first step of the purification procedure, describe how you can use an affinity column to capture the protein. You can either design a specific affinity column or a protein construct with a specific tag. In the latter case, specify both the tag and the column that recognizes the tag. (2 pts) B) For the second step of the purification procedure, ion exchange chromatography is used. The isoelectric point of the protein (PI) is pH 8 and the buffers used for the ion exchange chromatography are at pH 6. Will Protein D be positively charged or negatively charged in the buffers? Should anion or cation exchange columns be used? (2 pts) C) For the last step of the purification procedure, gel filtration chromatography is used to separate the dimer from a small amount of monomer. Which species, the dimer or the monomer, will elute first from the column? (2 pts)
Read DetailsTwo enzymes of unknown concentrations, A and B, act on the s…
Two enzymes of unknown concentrations, A and B, act on the same substrate, S. The initial velocity (V0) of the reaction catalyzed by Enzyme B is 60% of the V0 for Enzyme A when both enzymes are assayed at [S]= 100 mM. Enzyme A has a Km of 20 mM, and enzyme B has a Km of 100 mM. Both Enzyme A and B have a Vmax of 120 mM/s. (6 pts) A) What is the initial velocity (V0) for Enzyme A with its kinetic parameters and [S] provided? (3 pts) B) From these results, can you draw the conclusion on whether Enzyme A’s kcat is higher/lower than or equal to that of Enzyme B? Explain. (3 pts)
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