MCAT Chemical and Physical Foundations of Biological Systems 13 — Flashcards

Use the following information to answer questions:

A scientist accidentally mixed together concentrated pure samples of four well-characterized human proteins. The proteins were diluted into buffer of pH 6.0. The following table provides general data about the four proteins:

The scientist first separated the proteins based on molecular weight, which allowed for the isolation of glucokinase and transferrin because their molecular weights were distinct. The buffer was exchanged in the solution containing the other two proteins, replacing the pH 6.0 buffer with pH 5.0 buffer. The scientist then used the difference in pI to separate calmodulin I and hemoglobin by anion exchange chromatography, as the molecular weights of these proteins were too close to separate by the previous method without time-consuming optimization. After obtaining pure samples of the four proteins through this purification strategy, the scientist added appropriate cofactors to the proteins, took UV-visible spectra of each protein, and then tested the binding of several molecules to each protein in order to confirm the appropriate identities of the four proteins. The UV-visible spectrum of hemoglobin notably included a large Soret peak around 412 nm, and this sample was successfully able to bind oxygen.