Publications by authors named "Hannah Valentino"

Article Synopsis
  • - The study investigated a diverse group of 95 enzymes from the N-terminal nucleophile hydrolase superfamily, focusing on their ability to hydrolyze synthetic polyamides like nylon.
  • - About 40% of these enzymes demonstrated significant nylon hydrolase activity, comparable to the well-known enzyme NylC, without any clear link between their evolutionary relationships and their hydrolytic capabilities.
  • - Researchers identified several enzymes with strong substrate selectivity, especially those that efficiently processed Nylon 6,6, and also analyzed the crystal structure of a specific hydrolase to better understand the factors affecting its activity and selectivity.
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OxaD is a flavin-dependent monooxygenase (FMO) responsible for catalyzing the oxidation of an indole nitrogen atom, resulting in the formation of a nitrone. Nitrones serve as versatile intermediates in complex syntheses, including challenging reactions like cycloadditions. Traditional organic synthesis methods often yield limited results and involve environmentally harmful chemicals.

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CreE is a flavin-dependent monooxygenase (FMO) that catalyzes three sequential nitrogen oxidation reactions of L-aspartate to produce nitrosuccinate, contributing to the biosynthesis of the antimicrobial and antiproliferative nautral product, cremeomycin. This compound contains a highly reactive diazo functional group for which the reaction of CreE is essential to its formation. Nitro and diazo functional groups can serve as potent electrophiles, important in some challenging nucleophilic addition reactions.

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Enzymatic biodegradation of polymers, such as polyamides (PA), has the potential to cost-effectively reduce plastic waste, but enhancements in degradation efficiency are needed. Engineering enzymes through directed evolution is one pathway toward identification of critical domains needed for improving activity. However, screening such enzymatic libraries (100s-to-1000s of samples) is time-consuming.

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-hydroxylating monooxygenases (NMOs) are a subclass of flavin-dependent enzymes that hydroxylate nitrogen atoms. Recently, unique NMOs that perform multiple reactions on one substrate molecule have been identified. Fosfazinomycin M (FzmM) is one such NMO, forming nitrosuccinate from aspartate (Asp) in the fosfazinomycin biosynthetic pathway in some sp.

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is an opportunistic pathogen with a high mortality rate due to multi-drug-resistant strains. The synthesis and uptake of the iron-chelating siderophores acinetobactin (Acb) and preacinetobactin (pre-Acb) have been shown to be essential for virulence. Here, we report the kinetic and structural characterization of BauF, a flavin-dependent siderophore-interacting protein (SIP) required for the reduction of Fe(III) bound to Acb/pre-Acb and release of Fe(II).

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The flavin reductase (FRED) and isobutylamine -hydroxylase (IBAH) from constitute a two-component, flavin-dependent monooxygenase system that catalyzes the first step in valanimycin biosynthesis. FRED is an oxidoreductase that provides the reduced flavin to IBAH, which then catalyzes the hydroxylation of isobutylamine (IBA) to isobutylhydroxylamine (IBHA). In this work, we used several complementary methods to investigate FAD binding, steady-state and rapid reaction kinetics, and enzyme-enzyme interactions in the FRED:IBAH system.

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Allicin is a component of the characteristic smell and flavor of garlic (). A flavin-containing monooxygenase (FMO) produced by (AsFMO) was previously proposed to oxidize -allyl-l-cysteine (SAC) to alliin, an allicin precursor. Here, we present a kinetic and structural characterization of AsFMO that suggests a possible contradiction to this proposal.

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The catalytic cycle of most flavin-dependent enzymes can be divided into oxidative and reductive half-reactions. Although some enzymes are oxidized by electron carrier proteins or organic compounds, many use oxygen as the final electron acceptor. In order to properly study the reductive half-reaction of flavin-dependent enzyme that react with oxygen, as in the case of oxidases and monooxygenases, it is necessary to establish anaerobic conditions that will only allow the reduction process to be monitored.

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The redox-neutral reaction catalyzed by 2-haloacrylate hydratase (2-HAH) leads to the conversion of 2-chloroacrylate to pyruvate. Previous mechanistic studies demonstrated the formation of a flavin-iminium ion as an important intermediate in the 2-HAH catalytic cycle. Time-resolved flavin absorbance studies were performed in this study, and the data showed that the enzyme is capable of stabilizing both anionic and neutral flavin semiquinone species.

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