Nature is a valuable source of inspiration in the design of catalysts, and various approaches are used to elucidate the mechanism of hydrogenases, the enzymes that oxidize or produce H2. In FeFe hydrogenases, H2 oxidation occurs at the H-cluster, and catalysis involves H2 binding on the vacant coordination site of an iron centre. Here, we show that the reversible oxidative inactivation of this enzyme results from the binding of H2 to coordination positions that are normally blocked by intrinsic CO ligands. This flexibility of the coordination sphere around the reactive iron centre confers on the enzyme the ability to avoid harmful reactions under oxidizing conditions, including exposure to O2. The versatile chemistry of the diiron cluster in the natural system might inspire the design of novel synthetic catalysts for H2 oxidation.
Aldehyde oxidase (AO) is a molybdenum-containing enzyme involved in the clearance of drug compounds containing aldehydes and N-containing heterocyclic fragments. AO has gained considerable interest in recent years because of examples of too fast clearance of drug compounds in development. Thus, it is important to be able to predict AO-mediated drug metabolism. Therefore, we have characterized the structural and energetic aspects of different mechanisms with density functional theory using the molybdenum cofactor as a model for the reactive part of the enzyme. For a series of 6-substituted 4-quinazolinones, the trend in activation energies is the same for three tested reaction mechanisms. Using the concerted mechanism as a model for the enzymatic reaction, the transition states (TSs) for the formation of all possible metabolites for a series of known AO substrates were determined. The lowest activation energies correspond in all cases to the experimentally observed sites of metabolism (SOMs). Various molecular properties were calculated and investigated as more easily determinable markers for reactivity. The stabilities of both intermediates and products correlate to some extent with the TS energies and may be used to predict the SOM. The electrostatic-potential-derived charges are also good markers for the prediction of the experimental SOM for this set of compounds and may pave the way for the development of fast methods for the prediction of SOM for AO substrates.
Neuraminidase activity is essential for the infection and propagation of paramyxoviruses, including human parainfluenza viruses (hPIVs) and the Newcastle disease virus (NDV). Thus, many inhibitors have been developed based on the 2-deoxy-2,3-didehydro-d-N-acetylneuraminic acid inhibitor (DANA) backbone. Along this line, herein we report a series of neuraminidase inhibitors, having C4 (p-toluenesulfonamido and azido substituents) and C5 (N-perfluorinated chains) modifications to the DANA backbone, resulting in compounds with 5- to 15-fold greater potency than the currently most active compound, the N-trifluoroacetyl derivative of DANA (FANA), toward the NDV hemagglutinin-neuraminidase (NDV-HN). Remarkably, these inhibitors were found to be essentially inactive against the human sialidase NEU3, which is present on the outer layer of the cell membrane and is highly affected by the current NDV inhibitor FANA.
Motivation Cytochromes P450 are the most important class of drug metabolizing enzymes. Prediction of drug metabolism is important in development of new drugs, to understand and reduce adverse drug reactions and to reduce animal testing. Results SMARTCyp 3.0 is an updated version of our previous web server for prediction of site-of-metabolism for Cytochrome P450-mediated metabolism, now in Python 3 with increased structural coverage and new features. The SMARTCyp program is a first principle-based method using density functional theory determined activation energies for more than 250 molecules to identify the most likely site-of-metabolism. New features include a similarity measure between the query molecule and the model fragment, a new graphical interface and additional parameters expanding the structural coverage of the SMARTCyp program. Availability and implementation The SMARTCyp server is freely available for use on the web at smartcyp.sund.ku.dk. Supplementary information Supplementary data are available at Bioinformatics online.
Aldehyde Oxidase (AO) is an enzyme involved in the metabolism of aldehydes and N-containing heterocyclic compounds. Many drug compounds contain heterocyclic moieties, and AO metabolism has lead to failure of several late-stage drug candidates. Therefore, it is important to take AO-mediated metabolism into account early in the drug discovery process, and thus, to have fast and reliable models to predict the site of metabolism (SOM). We have collected a dataset of 78 substrates of human AO with a total of 89 SOMs and 347 non-SOMs and determined atomic descriptors for each compound. The descriptors comprise NMR shielding and ESP charges from density functional theory (DFT), NMR chemical shift from ChemBioDraw, and Gasteiger charges from RDKit. Additionally, atomic accessibility was considered using 2D-SASA and relative span descriptors from SMARTCyp. Finally, stability of the product, the metabolite, was determined with DFT and also used as a descriptor. All descriptors have AUC larger than 0.75. In particular, descriptors related to the chemical shielding and chemical shift (AUC = 0.96) and ESP charges (AUC = 0.96) proved to be good descriptors. We recommend two simple methods to identify the SOM for a given molecule: 1) use ChemBioDraw to calculate the chemical shift or 2) calculate ESP charges or chemical shift using DFT. The first approach is fast but somewhat difficult to automate, while the second is more time-consuming, but can easily be automated. The two methods predict correctly 93% and 91%, respectively, of the 89 experimentally observed SOMs.
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