ORCID Profile
0000-0002-6990-6973
Current Organisations
Spanish National Research Council
,
Peking University
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Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 2022
Publisher: American Chemical Society (ACS)
Date: 18-01-2008
DOI: 10.1021/BI7020298
Abstract: Lignin degradation by fungal peroxidases is initiated by one-electron transfer to an exposed tryptophan radical, a reaction mediated by veratryl alcohol (VA) in lignin peroxidase (LiP). Versatile peroxidase (VP) differs not only in its oxidation of Mn2+ at a second catalytic site but also in its ability to directly oxidize different aromatic compounds. The catalytic tryptophan environment was compared in LiP and VP crystal structures, and six residues near VP Trp164 were modified by site-directed mutagenesis. Oxidation of Mn2+ was practically unaffected. However, several mutations modified the oxidation kinetics of the high-redox-potential substrates VA and Reactive Black 5 (RB5), demonstrating that other residues contribute to substrate oxidation by the Trp164 radical. Introducing acidic residues at the tryptophan environment did not increase the efficiency of VP oxidizing VA. On the contrary, all variants harboring the R257D mutation lost their activity on RB5. Interestingly, this activity was restored when VA was added as a mediator, revealing the LiP-type behavior of this variant. Moreover, combination of the A260F and R257A mutations strongly increased (20-50-fold) the apparent second-order rate constants for reduction of VP compounds I and II by VA to values similar to those found in LiP. Dissociation of the enzyme-product complex seemed to be the limiting step in the turnover of this improved variant. Nonexposed residues in the vicinity of Trp164 can also affect VP activity, as found with the M247F mutation. This was a direct effect since no modification of the surrounding residues was found in the crystal structure of this variant.
Publisher: MDPI AG
Date: 24-02-2022
DOI: 10.3390/IJMS23052494
Abstract: Human galectin-3 (hGal-3) is involved in a variety of biological processes and is implicated in wide range of diseases. As a result, targeting hGal-3 for clinical applications has become an intense area of research. As a step towards the development of novel hGal-3 inhibitors, we describe a study of the binding of two Se-containing hGal-3 inhibitors, specifically that of di(β-D-galactopyranosyl)selenide (SeDG), in which two galactose rings are linked by one Se atom and a di(β-D-galactopyranosyl)diselenide (DSeDG) analogue with a diseleno bond between the two sugar units. The binding affinities of these derivatives to hGal-3 were determined by 15N-1H HSQC NMR spectroscopy and fluorescence anisotropy titrations in solution, indicating a slight decrease in the strength of interaction for SeDG compared to thiodigalactoside (TDG), a well-known inhibitor of hGal-3, while DSeDG displayed a much weaker interaction strength. NMR and FA measurements showed that both seleno derivatives bind to the canonical S face site of hGal-3 and stack against the conserved W181 residue also confirmed by X-ray crystallography, revealing canonical properties of the interaction. The interaction with DSeDG revealed two distinct binding modes in the crystal structure which are in fast exchange on the NMR time scale in solution, explaining a weaker interaction with hGal-3 than SeDG. Using molecular dynamics simulations, we have found that energetic contributions to the binding enthalpies mainly differ in the electrostatic interactions and in polar solvation terms and are responsible for weaker binding of DSeDG compared to SeDG. Selenium-containing carbohydrate inhibitors of hGal-3 showing canonical binding modes offer the potential of becoming novel hydrolytically stable scaffolds for a new class of hGal-3 inhibitors.
Publisher: Proceedings of the National Academy of Sciences
Date: 08-07-2020
Abstract: Emergence of the pathogen Klebsiella pneumoniae (particularly of carbapenem-resistant strains) is considered a dire threat to public health. Resistance and virulence determinants may favor the emergence of untreatable infections. Understanding the mechanisms involved in the pathogenesis and epidemicity of K. pneumoniae is essential for managing outbreaks and developing treatments. Here we identify a CUP system (Kpi) and infer the epidemiology of Kpi + K. pneumoniae in Europe. We demonstrate a direct link between Kpi presence and K . pneumoniae persistence in the hospital environment. Adherence of the bacterium to different cell types enables host colonization, favoring nosocomial outbreaks and spread of infection. Kpi appears to play a key role in the host–pathogen interaction and is associated with the worldwide-disseminated ST-15 clone.
No related grants have been discovered for Antonio Romero Garrido.