A solution of $0\mathrm{.}1\%$ sodium dodecyl sulfate $($SDS$)$ binds so strongly to polypeptide chains that one detergent molecule is suffcient to saturate two amino acid residues. For a protein with a molecular weight of $60,000$ in $0\mathrm{.}1\%$ SDS$,$ estimate the effect on the electrical charge per protein molecule.