Activated conformers of Escherichia coli sulfite reductase heme protein subunit.

Published

Journal Article

The heme protein subunit of Escherichia coli sulfite reductase shows enhanced reactivity with its substrate and a number of other ligands after a cycle of reduction and reoxidation at alkaline pH. At pH 9.5 this variant of the enzyme possesses at least four EPR-detectable, chloride-sensitive high-spin conformers, in contrast to the single chloride-insensitive species observed in the oxidized, resting enzyme at pH 7.7. Quantitative reversal of the spectral and ligand-binding properties of the "activated" enzyme to those of the resting enzyme is observed on reacidification to pH 7.7. At intermediate pH values, there occurs an acid-catalyzed relaxation of the activated enzyme to the resting form. This reaction is distinct from the one responsible for the accelerated ligand binding and production of multiple EPR conformers, which appears to be regulated by a process with a pK of 8.5.

Full Text

Duke Authors

Cited Authors

  • Young, LJ; Siegel, LM

Published Date

  • 1988-07-12

Published In

Volume / Issue

  • 27 / 14

Start / End Page

  • 4991 - 4999

PubMed ID

  • 2844246

Pubmed Central ID

  • 2844246

International Standard Serial Number (ISSN)

  • 0006-2960

Language

  • eng

Conference Location

  • United States