Scripps VIVO scripps research logo

  • Index
  • Log in
  • Home
  • People
  • Organizations
  • Research
  • Events
Search form

Proton sharing between cysteine thiols in Escherichia coli thioredoxin: implications for the mechanism of protein disulfide reduction

Academic Article
uri icon
  • Overview
  • Identity
  • Additional Document Info
  • View All
scroll to property group menus

Overview

authors

  • Jeng, M. F.
  • Holmgren, A.
  • Dyson, Jane

publication date

  • August 1995

journal

  • Biochemistry  Journal

abstract

  • Proton sharing between acidic groups has been observed in the active sites of several enzymes, including bacteriorhodopsin, aspartic proteases, and ribonuclease HI. We here report NMR observations suggestive of proton sharing between cysteine thiols in the active site of the oxidation-reduction enzyme thioredoxin. The pKas of the two cysteine thiols in the Escherichia coli protein are removed from the expected value of 8.4 by approximately 1 pH unit in either direction, upward and downward. Further, the C beta resonances of both residues show clearly the effects of both of these pKas, indicating that the titrations of the two thiol groups are intimately linked. This behavior strongly suggests that the low pKa ascribed to the deprotonation of the Cys 32 thiol most likely arises through the interaction and close approach of the thiol of Cys 35, with the thiolate anion of Cys 32 stabilized through the sharing of the remaining thiol proton, nominally attached to Cys 35. These observations provide a rationale for the mediation of active site pH control, an important aspect of the mechanism of thioredoxin and other proteins with catalytic thioredoxin domains, such as protein disulfide isomerases.

subject areas

  • Carbon Isotopes
  • Cysteine
  • Escherichia coli
  • Isomerases
  • Magnetic Resonance Spectroscopy
  • Oxidation-Reduction
  • Protein Disulfide-Isomerases
  • Protons
  • Sulfhydryl Compounds
  • Thioredoxins
scroll to property group menus

Identity

International Standard Serial Number (ISSN)

  • 0006-2960

Digital Object Identifier (DOI)

  • 10.1021/bi00032a001

PubMed ID

  • 7640264
scroll to property group menus

Additional Document Info

start page

  • 10101

end page

  • 10105

volume

  • 34

issue

  • 32

©2021 The Scripps Research Institute | Terms of Use | Powered by VIVO

  • About
  • Contact Us
  • Support