Question

During an isoelectric focusing procedure, cytokine Z migrated closer to the cathode than the control protein. This is most likely because Ctyokine Z has a higher concentration of which amino acid?

A. D
B. E
C. K
D. T

Answer 1

Cytokine Z likely has a higher concentration of lysine (K), as it migrated toward the cathode during isoelectric focusing, indicating it had a net positive charge under the conditions of the experiment. Option C.

Step-by-step explanation:

During isoelectric focusing (IEF), proteins are separated based on their isoelectric point (pI), which is the pH at which a protein has an equal number of positive and negative charges.

If Cytokine Z migrated closer to the cathode than a control protein during IEF, it would be because Cytokine Z has a net positive charge under the conditions of the experiment.

Since the cathode is negatively charged, it attracts positively charged particles. Therefore, Cytokine Z having a higher concentration of amino acids with positive charges at the experiment's pH would explain its movement towards the cathode.

Among the options given (D, E, K, T), amino acid K (lysine) has a side chain with a positively charged group at physiological pH. Consequently, a higher concentration of lysine would likely confer a net positive charge to Cytokine Z, causing it to move towards the cathode. So Option C.