The Process of Immobilization of ZnO Nanorods Surface with Galactose Oxidase

ZnO nanorods, with the c-axis orientation used for transparent conductors, solar cells, sensors especially the functionalized ZnO nanorods with some kinds of enzymes have been used for biosensor. In this work, we describe the process immobilization of galactose oxidase on ZnO nanorods surface with glutaraldehyde as a cross-linker molecule to make the working electrode in electrochemical biosensor. ZnO nanorods were grown on FTO （Fluorine-doped tin oxide） substrate by solution method at low temperature. The crystalline phase and orientation of ZnO nanorods were identified using X-ray diffraction. The efficiency of the immobilization was calculated by Braford method showed that about 36% enzyme content was immobilized on ZnO nanorods surface. The working electrode based on the immobilized ZnO nanorods was tested in galactose solution by CV （cyclic voltammetry） method indicated the value of current intensity is about 0.14 μA. These results clearly demonstrate the potential of galactose sensor based on ZnO nanorod.

Synthesis and Crystal Structure of Copper(II) Complex with Mixed Bipyridine and 2-Hydroxy-1-naphthaldehyde Ligands

A mononuclear copper(II) complex, [Cu(bipy)(naph)(ClO4)] (where bipy is bipyridine and naph is 2-hydroxy-1-naphthaldehyde), was synthesized and characterized by X-ray single-crystal structure analysis. The crystal is triclinic, space group P ?with a = 9.245(4), b = 9.962(4), c = 10.809(7) ? a = 84.83(5), b =82.35(4), g = 81.02(4), V = 972.1 ?, C21H15ClCuN2O6 Mr = 490.36, Z = 2, F(000) = 498, Dx = 1.68 g/cm3, m = 13.05 cm-1, R = 0.078, Rw = 0.081 for 2295 observed reflections with I > 3s(I). The copper(II) ion is coordinated by two nitrogen atoms of bipy and two oxygen atoms of naph in the equatorial plane, with an axial perchlorate oxygen-copper(II) bond to copper(II) ion to form square-pyramidal coordination geometry. The coordination environment of copper(II) is similar to the active site of galactose oxidase and this compound may also be considered as the structural model of galactose oxidase.

Enzymatic Synthesis of Methyl-Galactoaldehyde

Methyl-galactosides were oxidized at room temperature by galactose oxidase in a one-step reaction and afforded methyl-galactoaldehyde in excellent yield and high purity. The resulting galactoaldehyde as a useful intermediate can be directly used in glycopeptide synthesis.

Copper-radical oxidases: A diverse group of biocatalysts with distinct properties and a broad range of biotechnological applications

Copper-radical oxidases(CROs)catalyze the two-electron oxidation of a large number of primary alcohols includ-ing carbohydrates,polyols and benzylic alcohols as well as aldehydes and𝛼-hydroxy-carbonyl compounds while reducing molecular oxygen to hydrogen peroxide.Initially,CROs like galactose oxidase and glyoxal oxidase were identified only in fungal secretomes.Since the last decade,their representatives have also been identified in some bacteria.CROs are grouped in the AA5 family of“auxiliary activities”in the database of Carbohydrate-Active enzymes.Despite low overall sequence similarity and different substrate specificities,sequence alignments and the solved crystal structures revealed a conserved architecture of the active sites in all CROs,with a mononuclear copper ion coordinated to an axial tyrosine,two histidines,and a cross-linked cysteine-tyrosyl radical cofactor.This unique post-translationally modified protein cofactor has attracted much attention in the past,which resulted in a large number of reports that shed light on key steps of the catalytic cycle and physico-chemical properties of CROs.Thanks to their broad substrate spectrum accompanied by the only need for molecular oxygen for catal-ysis,CROs since recently experience a renaissance and have been applied in various biocatalytic processes.This review provides an overview of the structural features,catalytic mechanism and substrates of CROs,presents an update on the engineering of these enzymes to improve their expression in recombinant hosts and to enhance their activity,and describes their potential fields of biotechnological application.