Substitution with selenomethionine can enhance the stability of methionine-rich proteins

Nadine C. Gassner, Walter A. Baase, Andrew C. Hausrath, Brian W. Matthews

Research output: Contribution to journalArticlepeer-review

27 Scopus citations


The availability of a series of phage T4 lysozymes with up to 14 methionine residues incorporated within the protein has made it possible to systematically compare the effect on protein stability of selenomethionine relative to methionine. Wild-type lysozyme contains two fully buried methionine residues plus three more on the surface. The substitution of these methionine residues with selenomethionine slightly stabilizes the protein. As more and more methionine residues are substituted into the protein, there is a progressive loss of stability. This is, however, increasingly offset in the selenomethionine variants, ultimately resulting in a differential increase in melting temperature of about 7°C. This increase, corresponding to about 0.25 kcal/mol per substitution, is in reasonable agreement with the difference in the solvent transfer free energy between the two amino acids.

Original languageEnglish (US)
Pages (from-to)17-20
Number of pages4
JournalJournal of Molecular Biology
Issue number1
StatePublished - Nov 19 1999


  • Anomalous scattering
  • MAD phasing
  • Structure determination
  • T4 lysozyme

ASJC Scopus subject areas

  • Structural Biology
  • Molecular Biology


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