You have two purified samples of protein Y: the wild-type (nonmutated) protein and a mutant version with a single amino acid substitution. When washed through the same gel- filtration 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 protein Y normally forms dimers
(b) a change that results in the mutant protein acquiring an overall positive instead of a negative charge
(c) a change that results in the mutant protein being larger than the wild-type protein
(d) a change that results in the mutant protein having a slightly different shape from the wild-type protein
Answer: A