Enzymatic reduction and oxidation of fibre-bound azo-dyes

A new customer and environmental friendly method of hair bound dye decolouration was developed. Biotransformation of the azo-dyes Flame Orange and Ruby Red was studied using different oxidoreductases. The pathways of azo dye conversion by these enzymes were investigated and the intermediates and metabolites were identified and characterised using UV–vis spectroscopy, high-performance liquid chromatography (HPLC) and mass spectrometry (MS). Laccase from Pycnoporus cinnabarinus, manganese peroxidase (MnP) from Nematoloma frowardii and the novel Agrocybe aegerita peroxidase (AaP) were found to use a similar mechanism to convert azo dyes. They N-demethylated the dyes and concomitantly polymerized them to some extent. On the other hand the mechanism for cleavage of the azo bond by azo-reductases of Bacillus cereus and B. subtilis was based on reduction of the azo bond at the expense of NAD(P)H

Role of tyrosine 129 in the active site of spinach glycolate oxidase

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66136/1/j.1432-1033.1993.tb17852.x.pd

Rationally engineered flavin-dependent oxidase reveals steric control of dioxygen reduction

The ability of flavoenzymes to reduce dioxygen varies greatly and is controlled by the protein environment that can cause either a rapid (oxidases) or sluggish (dehydrogenases) reaction. Previously, a “gatekeeper” amino acid residue was identified that controls the reactivity to dioxygen in proteins from the vanillyl alcohol oxidase superfamily of flavoenzymes. We have identified an alternate gatekeeper residue that similarly controls dioxygen reactivity in the grass pollen allergen Phl p 4, a member of this superfamily, which has glucose dehydrogenase activity and the highest redox potential measured in a flavoenzyme. A substitution at the alternate gatekeeper site (I153V) transformed the enzyme into an efficient oxidase by increasing dioxygen reactivity by a factor of 60,000. An inverse exchange (V169I) in the structurally related berberine bridge enzyme (BBE) lowered its dioxygen reactivity by a factor of 500. Structural and biochemical characterization of these and additional variants showed that our model enzymes have a cavity binding an anion and resembling the “oxyanion hole” in the proximity of the flavin ring. We showed also that steric control of access to this site is the most important parameter affecting dioxygen reactivity in BBE-like enzymes. Analysis of flavin-dependent oxidases from other superfamilies revealed similar structural features suggesting that dioxygen reactivity might be governed by a common mechanistic principle.This is an author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by FEBS (Federation of European Biochemical Societies) and published by John Wiley & Sons, Inc. It can be found at: http://febs.onlinelibrary.wiley.com/hub/journal/10.1111/%28ISSN%291742-4658

Engineering of NADPH Supply Boosts Photosynthesis-Driven Biotransformations

was reached, allowing the complete conversion of a 60 mM substrate solution within 4 h

Ступінь приверженості до лікування та його ефективність у пацієнтів з гіпертонічною хворобою залежно від способу життя

Vitamin C is a widely used vitamin. Here we review the occurrence and properties of aldonolactone oxidoreductases, an important group of flavoenzymes responsible for the ultimate production of vitamin C and its analogs in animals, plants, and single-cell organisms

LeSBT1, a subtilase from tomato plants

The cDNA of a tomato subtilase designated LeSBT1 was cloned from a tomato flower cDNA library. The deduced amino acid sequence indicated for LeSBT1 the structure of a prepro-protein targeted to the secretory pathway by virtue of an amino-terminal signal peptide. LeSBT1 was expressed in the baculovirus/insect cell system and a processed 73-kDa form of LeSBT1, lacking both signal peptide and prodomain, was purified to homogeneity from culture supernatants, This 73-kDa LeSBT1, however, lacked proteolytic activity. Zymogen activation to yield 68-kDa LeSBT1 required the additional processing of an amino-terminal autoinhibitory peptide in a strictly pH-dependent manner. Mature 68-kDa LeSBT1 showed highest activity at acidic pH consistent with its presumed localization in the apoplast of the plant cell. In comparison to other plant subtilases, LeSBT1 exhibited a narrower substrate specificity in that it cleaves only polypeptide substrates preferentially but not exclusively carboxyl-terminal of glutamine residues. The possible involvement of LeSBT1 in selective proprotein processing is discussed with reference to the related mammalian proprotein convertases