Question

You have two purified samples of protein Y: the wild-type (non mutated) protein and a mutant version with a single amino acid substitution. When washed through the same gel-filtration (size exclusion) column, mutant protein Y runs through the column more slowly than the normal protein. Which of the following changes in the mutant protein is most likely to explain this result?

1) The mutant protein has a larger molecular weight than the normal protein.
2) The mutant protein has a smaller molecular weight than the normal protein.
3) The mutant protein has a higher affinity for the gel-filtration column than the normal protein.
4) The mutant protein has a lower affinity for the gel-filtration column than the normal protein.

Answer 1

The mutant protein runs through the gel-filtration column more slowly than the normal protein, indicating a difference in size or affinity. The most likely explanation is that the mutant protein has a larger molecular weight than the normal protein.

Step-by-step explanation:

The mutant protein runs through the gel-filtration column more slowly than the normal protein. This suggests that there is a difference in the size or affinity for the gel-filtration column between the two proteins. Option 1) The mutant protein has a larger molecular weight than the normal protein is the most likely explanation for this result. A larger protein would take longer to pass through the column due to its increased size.