The hydrophobic core of Escherichia coli thioredoxin shows a high tolerance to nonconservative single amino acid substitutions.


Journal Article

A set of single amino acid substitutions has been constructed at positions Leu42 and Leu78 in the hydrophobic core of Escherichia coli thioredoxin. This protein is required for the in vivo assembly of filamentous bacteriophages such as M13. Almost all the mutants retain this activity regardless of the change in size, hydrophobic nature, or charge of the substitution. Determination of the free energies of unfolding of the mutants containing charged residues shows that these are significantly destabilized as would be expected from simple considerations of the hydrophobic effect. Thioredoxin therefore represents a class of proteins where the often observed correlation between a particular biological activity and thermodynamic stability is not evident for single mutants in the all-or-none assay used. Native thioredoxin is very stable. Thus, structurally single mutants may not perturb the folding equilibrium or the dynamic behavior sufficiently for the effects to be sensed in vivo.

Full Text

Duke Authors

Cited Authors

  • Hellinga, HW; Wynn, R; Richards, FM

Published Date

  • November 17, 1992

Published In

Volume / Issue

  • 31 / 45

Start / End Page

  • 11203 - 11209

PubMed ID

  • 1445859

Pubmed Central ID

  • 1445859

International Standard Serial Number (ISSN)

  • 0006-2960

Digital Object Identifier (DOI)

  • 10.1021/bi00160a034


  • eng

Conference Location

  • United States