Probing the mechanism of flavin action in the oxidative decarboxylation catalyzed by salicylate hydroxylase.

Salicylate hydroxylase (NahG) is a FAD-dependent monooxygenase in which the reduced flavin activates O coupled to the oxidative decarboxylation of salicylate to catechol or uncoupled from substrate oxidation to afford HO. This chapter presents different methodologies in equilibrium studies, steady-state kinetics, and identification of reaction products, which were important to understand the SAr mechanism of catalysis in NahG, the role of the different FAD parts for ligand binding, the extent of uncoupled reaction, and the catalysis of salicylate's oxidative decarboxylation. These features are likely familiar to many other FAD-dependent monooxygenases and offer a potential asset for developing new tools and strategies in catalysis.

The role of remote flavin adenine dinucleotide pieces in the oxidative decarboxylation catalyzed by salicylate hydroxylase.

Salicylate hydroxylase (NahG) has a single redox site in which FAD is reduced by NADH, the O is activated by the reduced flavin, and salicylate undergoes an oxidative decarboxylation by a C(4a)-hydroperoxyflavin intermediate to give catechol. We report experimental results that show the contribution of individual pieces of the FAD cofactor to the observed enzymatic activity for turnover of the whole cofactor. A comparison of the kinetic parameters and products for the NahG-catalyzed reactions of FMN and riboflavin cofactor fragments reveal that the adenosine monophosphate (AMP) and ribitol phosphate pieces of FAD act to anchor the flavin to the enzyme and to direct the partitioning of the C(4a)-hydroperoxyflavin reaction intermediate towards hydroxylation of salicylate.

Transformation of xylan into value-added biocommodities using Thermobacillus composti GH10 xylanase.

Enzymatic transformation of xylans into renewable fuels and value-added products is mediated by xylanases. Here we describe the biochemical and X-ray structural characterization of Thermobacillus composti GH10 xylanase (TcXyn10A) at 2.1 Å resolution aiming to unravel details of its recognition of glucurono- and arabinoxylan at a molecular level.

Crystallographic structure and molecular dynamics simulations of the major endoglucanase from Xanthomonas campestris pv. campestris shed light on its oligosaccharide products release pattern.

Cellulases are essential enzymatic components for the transformation of plant biomass into fuels, renewable materials and green chemicals. Here, we determined the crystal structure, pattern of hydrolysis products release, and conducted molecular dynamics simulations of the major endoglucanase from the Xanthomonas campestris pv. campestris (XccCel5A).

Catalytic mechanism for the conversion of salicylate into catechol by the flavin-dependent monooxygenase salicylate hydroxylase.

Salicylate hydroxylase (NahG) is a flavin-dependent monooxygenase that catalyzes the decarboxylative hydroxylation of salicylate into catechol in the naphthalene degradation pathway in Pseudomonas putida G7. We explored the mechanism of action of this enzyme in detail using a combination of structural and biophysical methods. NahG shares many structural and mechanistic features with other versatile flavin-dependent monooxygenases, with potential biocatalytic applications.