2j19

Publication Abstract from PubMed

The X-ray crystallographic analysis of redox-active systems may be complicated by photoreduction. Although radiolytic reduction by the probing X-ray beam may be exploited to generate otherwise short-lived reaction intermediates of metalloproteins, it is generally an undesired feature. Here, the X-ray-induced reduction of the three heme proteins myoglobin, cytochrome P450cam and chloroperoxidase has been followed by on-line UV-Vis absorption spectroscopy. All three systems showed a very rapid reduction of the heme iron. In chloroperoxidase the change of the ionization state from ferric to ferrous heme is associated with a movement of the heme-coordinating water molecule. The influence of the energy of the incident X-ray photons and of the presence of scavengers on the apparent reduction rate of ferric myoglobin crystals was analyzed.

Cryoradiolytic reduction of crystalline heme proteins: analysis by UV-Vis spectroscopy and X-ray crystallography.,Beitlich T, Kuhnel K, Schulze-Briese C, Shoeman RL, Schlichting I J Synchrotron Radiat. 2007 Jan;14(Pt 1):11-23. Epub 2006 Dec 15. PMID:17211068^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.