Question

A protein solution was placed in an analytic centrifuge and spun until equilibrium was reached. The measurement was then repeated. But it was realized, too late, that prior
to the second run, the protein had been denatured. The average size of a denatured protein is larger than that of a native, compact protein. (a) Do you expect the distribution of molecules to be the same, at equilibrium, for the two different runs? Explain. (b) The time that it takes to reach equilibrium depends on the sedimentation constant of the molecules. Which run will reach equilibrium faster, the one with the native protein, or the one with the denatured protein? Explain how you imagine the sedimentation process of the two molecules.

Answer 1

a) A centrifugation of protein can lead to denaturation. When native protein is subjected to physical and chemical change, protein loses its biological activity and is called denatured protein. Protein folding is the physical process by which a protein chain acquires its native. Denaturation of proteins is a process of transition from the folded to the unfolded, the primary sequence, rather than randomly distributed or clustered together. So the distribution of molecules not be the same, at equilibrium, for the two different runs.

b) The sedimentation coefficient of a particle characterizes its sedimentation during centrifugation. It is defined as the ratio of a particle's sedimentation velocity to the applied acceleration causing the sedimentation. The sedimentation speed is also the terminal velocity. The denatured protein will reach the equilibrium at a faster rate than the native protein as the sedimentation coefficient for denatured protein is higher.