2ih9

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spinqualitylabelsall models 2ih9, resolution 2.000Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

A high-dose crystal structure of a recombinant Melanocarbus albomyces laccase

Overview

Laccases (p-diphenol dioxygen oxidoreductases) belong to the family of, blue multicopper oxidases, which catalyse the four-electron reduction of, dioxygen to water concomitantly through the oxidation of substrate, molecules. Blue multicopper oxidases have four coppers, a copper (T1), forming a mononuclear site and a cluster of three coppers (T2, T3, and, T3') forming a trinuclear site. Because X-rays are known to liberate, electrons during data collection and may thus affect the oxidation state, of metals, we have investigated the effect of X-ray radiation upon the, crystal structure of a recombinant laccase from Melanocarpus albomyces, through the use of crystallography and crystal absorption spectroscopy., Two data sets with different strategies, a low and a high-dose data set, were collected at synchrotron. We have observed earlier that the, trinuclear site had an elongated electron density amidst coppers, suggesting dioxygen binding. The low-dose synchrotron structure showed, similar elongated electron density, but the high-dose X-ray radiation, removed the bulk of this density. Therefore, X-ray radiation could alter, the active site of laccase from M. albomyces. Absorption spectra of the, crystals (320, 420, and 590nm) during X-ray radiation were measured at a, home laboratory. Spectra clearly showed how that the band at 590nm had, vanished, resulting from the T1 copper being reduced, during the long, X-ray measurements. The crystal colour changed from blue to colourless., Absorptions at 320 and 420nm seemed to be rather permanent. The absorption, at 320nm is due to the T3 coppers and it is proposed that absorption at, 420nm is due to the T2 copper when dioxygen or a reaction intermediate is, close to this copper.

About this Structure

2IH9 is a Single protein structure of sequence from Melanocarpus albomyces with NAG, CU, CL, SO4 and 5AX as ligands. Active as Laccase, with EC number 1.10.3.2 Full crystallographic information is available from OCA.

Reference

A crystallographic and spectroscopic study on the effect of X-ray radiation on the crystal structure of Melanocarpus albomyces laccase., Hakulinen N, Kruus K, Koivula A, Rouvinen J, Biochem Biophys Res Commun. 2006 Dec 1;350(4):929-34. Epub 2006 Oct 5. PMID:17045575

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