The role of tryptophan in staphylococcal nuclease stability

Hong Yu Hu, Ming Chya Wu, Huey Jen Fang, Michael D. Forrest, Chin Kun Hu, Tian Yow Tsong, Hueih Min Chen

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


Staphylococcal nuclease (SNase) has a single Trp residue at position 140. Circular dichroism, intrinsic and ANS-binding fluorescence, chemical titrations and enzymatic assays were used to measure the changes of its structure, stability and activities as the Trp was mutated or replaced to other positions. The results show that W140 is critical to SNase structure, stability, and function. Mutants such as W140A, F61W/W140A, and Y93W/W140A have unfolding, corrupted secondary and tertiary structures, diminished structural stability and attenuated catalytic activity as compared to the wild type. The deleterious effects of W140 substitution cannot be compensated by concurrent changes at topographical locations of position 61 or 93. Local hydrophobicity defined as a sum of hydrophobicity around a given residue within a distance is found to be a relevant property to SNase folding and stability.

Original languageEnglish
Pages (from-to)170-177
Number of pages8
JournalBiophysical Chemistry
Issue number3
StatePublished - Oct 2010


  • F61W/W140A
  • Local hydrophobicity
  • Staphylococcal nuclease
  • Tryptophan modification
  • W140A
  • Y93W/W140A


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