EPR Studies of Ligand Binding to the Type 2/Type 3 Cluster in Tree Laccase

Peyratout, Claire; Severns, John C.; Holm, S.R.; McMillin, David R.

doi:10.1006/abbi.1994.1460

Cited by 22 publications

(14 citation statements)

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“…While the catalysis at the T1 copper center is reasonably well understood, the detailed description of the catalytic events taking place at the three copper atoms in the dioxygen reduction site, is still the subject of intense debate. Exhaustive spectroscopic investigations at the T2/T3 cluster have been performed on laccases from the plant Rhus vernicifera [37][38][39][40] and from the fungus Polyporus versicolor 41 resulting in the description of the structure of the native and peroxy intermediates formed during the reduction of dioxygen to water at the trinuclear copper cluster [38][39][40] and questioning which of the copper atoms within the cluster is the EPR-active copper. 41 Obviously, a major point for the understanding of the catalysis at the dioxygen reduction site is the oxidation state of the different copper ions and the precise definition of their coordination distances and geometries.…”

Section: Discussionmentioning

confidence: 99%

The Structure of Rigidoporus lignosus Laccase Containing a Full Complement of Copper Ions, Reveals an Asymmetrical Arrangement for the T3 Copper Pair

Garavaglia

Cambria

Miglio

et al. 2004

Journal of Molecular Biology

147

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Section: Discussionmentioning

confidence: 99%

The Structure of Rigidoporus lignosus Laccase Containing a Full Complement of Copper Ions, Reveals an Asymmetrical Arrangement for the T3 Copper Pair

Garavaglia

Cambria

Miglio

et al. 2004

Journal of Molecular Biology

147

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“…This was achieved using the method of comparison of distance matrices of C ␣ atoms (Peyratout et al, 1994). Initially, an all against all comparison of hexapeptide length segments was carried out to obtain the root mean square deviation (RMSD) between the C ␣ distance matrices.…”

Section: Comparison Of Signature Sequences At Structural Levelmentioning

confidence: 99%

Combined sequence and structure analysis of the fungal laccase family

Kumar

Phale

Durani

et al. 2003

Biotech & Bioengineering

187

152

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Plant and fungal laccases belong to the family of multi-copper oxidases and show much broader substrate specificity than other members of the family. Laccases have consequently been of interest for potential industrial applications. We have analyzed the essential sequence features of fungal laccases based on multiple sequence alignments of more than 100 laccases. This has resulted in identification of a set of four ungapped sequence regions, L1-L4, as the overall signature sequences that can be used to identify the laccases, distinguishing them within the broader class of multi-copper oxidases. The 12 amino acid residues in the enzymes serving as the copper ligands are housed within these four identified conserved regions, of which L2 and L4 conform to the earlier reported copper signature sequences of multi-copper oxidases while L1 and L3 are distinctive to the laccases. The mapping of regions L1-L4 on to the three-dimensional structure of the Coprinus cinerius laccase indicates that many of the non-copper-ligating residues of the conserved regions could be critical in maintaining a specific, more or less C-2 symmetric, protein conformational motif characterizing the active site apparatus of the enzymes. The observed intraprotein homologies between L1 and L3 and between L2 and L4 at both the structure and the sequence levels suggest that the quasi C-2 symmetric active site conformational motif may have arisen from a structural duplication event that neither the sequence homology analysis nor the structure homology analysis alone would have unraveled. Although the sequence and structure homology is not detectable in the rest of the protein, the relative orientation of region L1 with L2 is similar to that of L3 with L4. The structure duplication of first-shell and second-shell residues has become cryptic because the intraprotein sequence homology noticeable for a given laccase becomes significant only after comparing the conservation pattern in several fungal laccases. The identified motifs, L1-L4, can be useful in searching the newly sequenced genomes for putative laccase enzymes.

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“…The mechanism of the laccase reaction has been reviewed (Reinharrimar, 1984;Peyratout et al, 1994) and consists of a single electron oxidation of a diphenol which generates a free radical (semi-quinone) which then converts to the quinone, either by enzyme catalysis or spontaneous disproportionation. Subsequently both the semiquinone and the full quinorie may undergo other non-enzymatic reactions; the most important of these are quinone polymerisation to form melanins and the semi-quinone, single electron mediated oxidation of other compounds.…”

Section: Laccase Structure and Reaction Mechanismmentioning

confidence: 99%