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Galactose Oxidase (galactose + oxidase)

Distribution by Scientific Domains

Chemistry	83%

Selected Abstracts

Combined Application of Galactose Oxidase and ,- N -Acetylhexosaminidase in the Synthesis of Complex Immunoactive N -Acetyl- D -galactosaminides

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 7-8 2005
Pavla Fialová
Abstract A high-yield preparatory procedure for the synthesis of p -nitrophenyl 2-acetamido-2-deoxy-,- D - galacto -hexodialdo-1,5-pyranoside (2) using the galactose oxidase from Dactylium dendroides in a batch reactor was developed. Enzymatic recognition of this aldehyde and the respective uronic acid 3 obtained by NaClO2 oxidation was studied using a set of 36 fungal ,- N -acetylhexosaminidases from Acremonium, Aspergillus, Penicillium and Talaromyces genera. The aldehyde 2 was readily hydrolysed by all tested ,- N -acetylhexosaminidases but neither the uronic acid 3 nor its methyl ester 4 were accepted. Molecular modelling with docking into the active centre of the ,- N -acetylhexosaminidase from Aspergillus oryzae revealed that the aldehyde 2 is processed as a C-6 geminal diol by the enzyme. The aldehyde 2 was tested for transglycosylation reactions using GlcNAc as an acceptor. The ,- N -acetylhexosaminidase from Talaromyces flavus gave the best yields (37%) of the transglycosylation product 2-acetamido-2-deoxy-,- D - galacto -hexodialdo-1,5-pyranosyl-(1,4)-2-acetamido- 2-deoxy- D -glucopyranose, which was oxidised in situ to yield the final product 2-acetamido-2-deoxy-,- D -galactopyranosyluronic acid-(1,4)-2-acetamido-2-deoxy- D -glucopyranose (6). Compounds 3 and 6 were shown to be high-affinity ligands for two natural killer cell activation receptors, NKR-P1A and CD69. For the latter receptor they turned out to be among the best ligands described so far. This increase was obviously due to the presence of a carboxy moiety. [source]

X-Ray Structures of Copper(II) and Nickel(II) Radical Salen Complexes: The Preference of Galactose Oxidase for Copper(II)

ANGEWANDTE CHEMIE, Issue 29 2010
Maylis Orio Dr.
Kupfer oder Nickel? Der gezeigte CuII -Salen-Komplex, ein Modell des aktiven Zentrums der Galactose-Oxidase (GO), liegt im Festkörper als lokalisiertes Radikal vor, wie an der chinoiden Verteilung der Bindungslängen in einem der Ringe zu erkennen ist. Die Struktur des radikalischen Liganden hängt nicht vom Metall ab, die Zusammensetzung des SOMO dagegen schon. Dies könnte die viel geringere Reaktivität des Ni-Komplexes erklären, ebenso wie die Tatsache, dass natürliche GO ein CuII -Zentrum bevorzugt. [source]

Oxidatively Robust Monophenolate-Copper(II) Complexes as Potential Models of Galactose Oxidase.

CHEMINFORM, Issue 23 2003
Robertus J. M. Klein Gebbink
No abstract is available for this article. [source]

Synthesis and Electrochemical Study of an Original Copper(II)-Capped Salen,Cyclodextrin Complex

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 29 2010
Elise Deunf
Abstract A new metallocapped cyclodextrin (CD) was synthesized by the regioselective debenzylation, induced by diisobutylaluminium hydride (DIBAL-H), of perbenzylated cyclodextrins. This reaction allowed for the efficient preparation of an unprecedented CD,salen type copper(II) complex. The electrochemical behavior of both the bound and unbound CD,salen compounds was investigated by cyclic voltammetry. Notably, it was shown that the presence of tert -butyl groups at the ortho - and para -positions of the salen aromatic rings stabilized the copper(II) phenoxyl radical species that was generated upon the one-electron oxidation of the starting compound. Importantly, this stabilization remained effective when the salen-type ligand was covalently attached to the CD. This allowed for investigations of the reactivity of the copper(II) phenoxyl radical complex towards a primary alcohol to be performed by cyclic voltammetry. This reaction can be considered as mimicking the behavior of galactose oxidase. However, under these conditions, no reactivity was observed in the presence of benzyl alcohol. This may be due to distortion, either of the initially square planar salen ligand after its grafting to the CD primary face, and/or of the CD itself. On the other hand, the electrochemical reduction of the un-grafted copper(II) salen-type ligand led to a transient anionic species that exhibited significant stability on the time-scale of the slow cyclic voltammetry measurement in the absence of the CD, but was unstable in the presence of the CD. In the latter case, it was demonstrated that the anionic species was protonated by the CD. Importantly, this protonation was not fast enough to prevent catalytic activation of iodomethane by the electro-generated copper(I)-capped salen CD complex. [source]

One-Pot Preparation of Polymer,Enzyme,Metallic Nanoparticle Composite Films for High-Performance Biosensing of Glucose and Galactose

ADVANCED FUNCTIONAL MATERIALS, Issue 11 2009
Yingchun Fu
Abstract New polymer,enzyme,metallic nanoparticle composite films with a high-load and a high-activity of immobilized enzymes and obvious electrocatalysis/nano-enhancement effects for biosensing of glucose and galactose are designed and prepared by a one-pot chemical pre-synthesis/electropolymerization (CPSE) protocol. Dopamine (DA) as a reductant and a monomer, glucose oxidase (GOx) or galactose oxidase (GaOx) as the enzyme, and HAuCl4 or H2PtCl6 as an oxidant to trigger DA polymerization and the source of metallic nanoparticles, are mixed to yield polymeric bionanocomposites (PBNCs), which are then anchored on the electrode by electropolymerization of the remaining DA monomer. The prepared PBNC material has good biocompatibility, a highly uniform dispersion of the nanoparticles with a narrow size distribution, and high load/activity of the immobilized enzymes, as verified by transmission/scanning electron microscopy and electrochemical quartz crystal microbalance. The thus-prepared enzyme electrodes show a largely improved amperometric biosensing performance, e.g., a very high detection sensitivity (99 or 129,µA cm,2 mM,1 for glucose for Pt PBNCs on bare or platinized Au), a sub-micromolar limit of detection for glucose, and an excellent durability, in comparison with those based on conventional procedures. Also, the PBNC-based enzyme electrodes work well in the second-generation biosensing mode. The proposed one-pot CPSE protocol may be extended to the preparation of many other functionalized PBNCs for wide applications. [source]