You have two purified samples of protein Y: the wild-type (nonmutated) protein and a mutant version. When washed through the same gel-filtration chromatography 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? a) the loss of a binding site on the mutant protein surface through which the protein Y normally forms dimers.
b) a change that results in the mutant protein's acquiring an overall positive instead of a negative charge.
c) a change that results in the mutant protein's being larger than the wild-type protein.
d) a change that results in the mutant protein's having a slightly different shape from the wild-type protein.