PMID: 23275172

Authors:

Merlino A, Fuchs MR, Pica A, Balsamo A, Dworkowski FS, Pompidor G, Mazzarella L, Vergara A

Title:

Selective X-ray-induced NO photodissociation in haemoglobin crystals: evidence from a Raman-assisted crystallographic study.

Journal:

Acta Crystallogr D Biol Crystallogr. 2013 Jan;69(Pt 1):137-40. doi:, 10.1107/S0907444912042229. Epub 2012 Dec 20.

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 beta 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.