Ascaris haemoglobin is a nitric oxide-activated 'deoxygenase'.

Journal Article (Journal Article)

The parasitic nematode Ascaris lumbricoides infects one billion people worldwide. Its perienteric fluid contains an octameric haemoglobin that binds oxygen nearly 25,000 times more tightly than does human haemoglobin. Despite numerous investigations, the biological function of this molecule has remained elusive. The distal haem pocket contains a metal, oxygen and thiol, all of which are known to be reactive with nitric oxide. Here we show that Ascaris haemoglobin enzymatically consumes oxygen in a reaction driven by nitric oxide, thus keeping the perienteric fluid hypoxic. The mechanism of this reaction involves unprecedented chemistry of a haem group, a thiol and nitric oxide. We propose that Ascaris haemoglobin functions as a 'deoxygenase', using nitric oxide to detoxify oxygen. The structural and functional adaptations of Ascaris haemoglobin suggest that the molecular evolution of haemoglobin can be rationalized by its nitric oxide related functions.

Full Text

Duke Authors

Cited Authors

  • Minning, DM; Gow, AJ; Bonaventura, J; Braun, R; Dewhirst, M; Goldberg, DE; Stamler, JS

Published Date

  • September 30, 1999

Published In

Volume / Issue

  • 401 / 6752

Start / End Page

  • 497 - 502

PubMed ID

  • 10519555

International Standard Serial Number (ISSN)

  • 0028-0836

Digital Object Identifier (DOI)

  • 10.1038/46822


  • eng

Conference Location

  • England