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Lead content was determined in wild growing mushrooms collected from two different areas in the Province of Lugo (NW Spain). It has been analyzed by graphite furnace atomic absorption spectrometry in 95 samples of 13 species (7 mycorrhizals and 6 saprophites). In an assessment of lead concentrations, the following factors have been considered: species and ecology, morphological portion, and traffic pollution. The average lead concentration of the samples was 1 ppm dry weight (dw). Saprophite species presented higher levels than mycorrhizal ones (< 1 ppm), Coprinus comatus reaching the maximum mean concentration with 2.06 and 2.79 ppm of dw in the hymenophore and the rest of the fruit body. Morphological portion, statistically, did not show significant difference between the two portions; however, Macrolepiota procera always presented lead high levels in the hymenophore in all samples. The effect due to traffic pollution has been specially observed in Coprinus comatus, presenting the highest concentration with values of 6.51 and 10.43 ppm, respectively, in samples collected in the city center. This species, as other researchers have indicated, could be considered as an indicator by lead contamination. The contribution of mushrooms to the weekly intake of lead was calculated and the possible health risk for the consumer is pointed out. These data are of great importance in view of toxicology and partly environmental protection.

New manganese(II) and manganese(III) complexes of substituted N,N 0 -bis(salicylidene)-1,2-diimino-2methylethane have been prepared and characterized. Elemental analysis, IR and EPR spectroscopies, mass spectrometry, magnetic measurements and the study of their redox properties have confirmed their respective formulae as Mn II L(H 2 O) 2 and Mn III L(H 2 O) n (ClO 4 ). Electron-withdrawing substituents on the phenyl rings of the ligand stabilize the oxidation state (II) for manganese, but the electron-donating substituents on the Schiff bases are those that lead to Mn(III) complexes, which behave as efficient peroxidase mimics in the presence of the water-soluble trap ABTS. The rate of peroxidase activity of the present complexes is significantly higher than that of other series of Mn-Schiff base compounds, probably due to their versatility in adopting in solution a structure that allows the coordination of the hydrogen peroxide substrate molecule to the manganese.

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The synthesis and structural and spectroscopic characterisation of 12 manganese(III)-Schiff-base complexes of the for-n and H 4 L n Schiff-base ligands were obtained by condensation of different diamines (1,2-diaminoethane, 1,2-diamino-2-methylethane, 1,2-diamino-2,2-dimethylethane, 1,3-diamino-2,2-dimethylpropane) and 2,3-dihydroxybenzaldehyde, 3-methoxy-2-hydroxybenzaldehyde or 3-ethoxy-2-hydroxybenzaldehyde.

In this paper we describe the electrochemical synthesis and characterization of new neutral manganese, iron, cobalt, nickel, copper, zinc, cadmium and lead complexes with the ligand bis(4-N-methylthiosemicarbazone)-2,6-diacetylpyridine, H4DAPTsz-Me. X-Ray structures of [Mn(H2DAPTsz-Me)(EtOH)2] 1, [Pb(H2DAPTsz-Me)] 3 and [Zn(H2DAPTsz-Me)]2.EtOH.2H2O 4, were also determined. In these complexes the ligand behaves as bis-deprotonated and SNNNS pentadentate. In the manganese complex the metal is heptacoordinated, in a distorted pentagonal-bipyramidal environment, with the N3S2 donor set of the ligand in the pentagonal girdle and two solvent molecules occupying the axial positions. In the lead complex 3 the metal is pentacoordinated, bound exclusively to the five donor atoms of the ligand, as a consequence of the existence of "inert pair effect". The bishelical zinc complex 4 shows each zinc atom with different coordination geometry, one octahedrally six-coordinate while the other is distorted tetrahedrally four-coordinate.

LiP (lignin peroxidase) from Trametopsis cervina has an exposed catalytic tyrosine residue (Tyr181) instead of the tryptophan conserved in other lignin-degrading peroxidases. Pristine LiP showed a lag period in VA (veratryl alcohol) oxidation. However, VA-LiP (LiP after treatment with H2O2 and VA) lacked this lag, and H2O2-LiP (H2O2-treated LiP) was inactive. MS analyses revealed that VA-LiP includes one VA molecule covalently bound to the side chain of Tyr181, whereas H2O2-LiP contains a hydroxylated Tyr181. No adduct is formed in the Y171N variant. Molecular docking showed that VA binding is favoured by sandwich π stacking with Tyr181 and Phe89. EPR spectroscopy after peroxide activation of the pre-treated LiPs showed protein radicals other than the tyrosine radical found in pristine LiP, which were assigned to a tyrosine-VA adduct radical in VA-LiP and a dihydroxyphenyalanine radical in H2O2-LiP. Both radicals are able to oxidize large low-redox-potential substrates, but H2O2-LiP is unable to oxidize high-redox-potential substrates. Transient-state kinetics showed that the tyrosine-VA adduct strongly promotes (>100-fold) substrate oxidation by compound II, the rate-limiting step in catalysis. The novel activation mechanism is involved in ligninolysis, as demonstrated using lignin model substrates. The present paper is the first report on autocatalytic modification, resulting in functional alteration, among class II peroxidases.

Three novel neutral manganese(III) complexes of stoichiometry Mn(R-amsal-3,5-di-tBu)(H 2 O) n [H 3 -R-amsal-3,5-ditBu = 3-aza-4-(2-hydroxyphenyl)-N-(2-hydroxyphenyl)but-3-enamide; (R = H, 4-Me, 5-tBu)] have been synthesised using potentially trianionic and pentadentate Schiff-base ligands containing an amide group. Complexes were thoroughly characterised by elemental analysis, FAB mass spectrometry, infrared spectroscopy, magnetic susceptibility measurements and molar conductivities. Recrystallisation of these complexes from methanol yielded single crystals of [Mn 2 (amsal-3,5-di-tBu) 2 (MeOH) 2 ] n 1, [Mn 2 (4-Me-amsal-3,5-di-tBu) 2 -