A single amino acid substitution in a histidine-transport protein drastically alters its mobility in sodium dodecyl sulfate-polyacrylamide gel electrophoresis

Biochemistry. 1979 Sep 18;18(19):4159-65. doi: 10.1021/bi00586a017.


Mutation hisJ5625 has altered the histidine-binding protein J of Salmonella typhimurium such that histidine transport is impaired, even though binding of histidine by the J protein is unimpaired [Kustu, S.G., & Ames, G.F. (1974) J. Biol. Chem. 249, 6976--6983]. We have determined by protein analytical methods that the only effect of this mutation has been the substitution of a cysteine residue for an arginine at a site in the interior of the polypeptide chain. This arginine residue is therefore potentially essential for the transport function of the protein. The mutant protein migrates in sodium dodecyl sulfate-polyacrylamide gel electrophoresis more slowly than the wild type protein, as if its molecular weight were greater by as much as 2000. Since this behavior is apparently due to a single amino acid replacement, a molecular weight difference even between two closely related proteins should not be inferred solely on the basis of sodium dodecyl sulfate gel electrophoresis.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acids / analysis
  • Biological Transport
  • Carrier Proteins* / metabolism
  • Electrophoresis, Polyacrylamide Gel
  • Histidine / metabolism*
  • Mutation
  • Peptide Fragments / analysis
  • Periplasmic Binding Proteins
  • Salmonella typhimurium / metabolism
  • Sodium Dodecyl Sulfate
  • Trypsin


  • Amino Acids
  • Carrier Proteins
  • Peptide Fragments
  • Periplasmic Binding Proteins
  • histidine-binding protein
  • Sodium Dodecyl Sulfate
  • Histidine
  • Trypsin