title: Selective X-ray-induced NO photodissociation in haemoglobin crystals: evidence from a Raman-assisted crystallographic study.
abstract: Despite their high physiological relevance, haemoglobin crystal structures with NO bound to haem constitute less than 1% of the total ligated haemoglobins (Hbs) deposited in the Protein Data Bank. The major difficulty in obtaining NO-ligated Hbs is most likely to be related to the oxidative denitrosylation caused by the high reactivity of the nitrosylated species with O(2). Here, using Raman-assisted X-ray crystallography, it is shown that under X-ray exposure (at four different radiation doses) crystals of nitrosylated haemoglobin from Trematomus bernacchii undergo a transition, mainly in the β chains, that generates a pentacoordinate species owing to photodissociation of the Fe-NO bond. These data provide a physical explanation for the low number of nitrosylated Hb structures available in the literature.
authors.affiliation: Department of Chemical Sciences, University of Naples `Federico II', Italy.
authors.forename: Antonello
authors.initials: A
authors.lastname: Merlino
authors.forename: Martin R
authors.initials: MR
authors.lastname: Fuchs
authors.forename: Andrea
authors.initials: A
authors.lastname: Pica
authors.forename: Anna
authors.initials: A
authors.lastname: Balsamo
authors.forename: Florian S N
authors.initials: FS
authors.lastname: Dworkowski
authors.forename: Guillaume
authors.initials: G
authors.lastname: Pompidor
authors.forename: Lelio
authors.initials: L
authors.lastname: Mazzarella
authors.forename: Alessandro
authors.initials: A
authors.lastname: Vergara
mesh_terms: D000818:Animals; D018360:Crystallography, X-Ray / Q000379:methods; D005399:Fishes; D006454:Hemoglobins / Q000737:chemistry* / Q000378:metabolism / Q000528:radiation effects*; D015591:Microspectrophotometry / Q000379:methods; D009569:Nitric Oxide / Q000737:chemistry* / Q000378:metabolism / Q000528:radiation effects*; D055668:Photochemical Processes / Q000528:radiation effects; D013059:Spectrum Analysis, Raman / Q000379:methods
chemical_list: D006454:Hemoglobins; D009569:Nitric Oxide