Structural basis for the root effect in haemoglobin.

Journal Article (Journal Article)

The remarkable ability of root effect haemoglobins to pump oxygen against high O2 gradients results from extreme, acid-induced reductions in O2 affinity and cooperativity. The long-sought mechanism for the root effect, revealed by the 2 angstrom crystal structure of the ligand-bound haemoglobin from Leiostomus xanthurus at pH 7.5, unexpectedly involves modulation of the R-state. Key residues strategically assemble positive-charge clusters across the allosteric beta1 beta2-interface in the R-state. At low pH, protonation of the beta N terminus and His 147(HC3)beta within these clusters is postulated to destabilize the R-state and promote the acid-triggered, allosteric R-->T switch with concomitant O2 release. Surprisingly, a set of residues specific to root effect haemoglobins recruit additional residues, conserved among most haemoglobins, to produce the root effect.

Full Text

Duke Authors

Cited Authors

  • Mylvaganam, SE; Bonaventura, C; Bonaventura, J; Getzoff, ED

Published Date

  • March 1996

Published In

Volume / Issue

  • 3 / 3

Start / End Page

  • 275 - 283

PubMed ID

  • 8605630

International Standard Serial Number (ISSN)

  • 1072-8368

Digital Object Identifier (DOI)

  • 10.1038/nsb0396-275


  • eng