Get access

Determinants of Ligand Affinity and Heme Reactivity in H-NOX Domains


  • Funding for this research was provided by the National Institutes of Health National Heart, Lung, and Blood Institute Award F32L090174 (E.E.W.), NIH grant GM 070671 (M.A.M.), and a grant from the Rogers Family Foundation (M.A.M.). We are grateful to Dr. Jay Winkler and the Beckman Institute Laser Resource Center at the California Institute of Technology for assistance with on-rate measurements, and members of the Marletta laboratory for critical reading of this manuscript. H-NOX=heme nitric oxide/oxygen.


original image

O2balks at extra bulk: The introduction of distal-pocket bulk into the Thermoanaerobacter tengcongensis H-NOX (heme nitric oxide/oxygen) domain caused key changes in the protein structure. Rearrangement of the heme pocket resulted in dramatic differences in O2-binding kinetics and heme reactivity (see picture).