Suchergebnisse

This article belongs to the Special Issue Novel Antibacterial Agents. ; The antibacterial activity of imidazole and imidazolium salts is highly dependent upon their lipophilicity, which can be tuned through the introduction of different hydrophobic substituents on the nitrogen atoms of the imidazole or imidazolium ring of the molecule. Taking this into consideration, we have synthesized and characterized a series of imidazole and imidazolium salts derived from L-valine and L-phenylalanine containing different hydrophobic groups and tested their antibacterial activity against two model bacterial strains, Gram-negative E. coli and Gram-positive B. subtilis. Importantly, the results demonstrate that the minimum bactericidal concentration (MBC) of these derivatives can be tuned to fall close to the cytotoxicity values in eukaryotic cell lines. The MBC value of one of these compounds toward B. subtilis was found to be lower than the IC50 cytotoxicity value for the control cell line, HEK-293. Furthermore, the aggregation behavior of these compounds has been studied in pure water, in cell culture media, and in mixtures thereof, in order to determine if the compounds formed self-assembled aggregates at their bioactive concentrations with the aim of determining whether the monomeric species were in fact responsible for the observed antibacterial activity. Overall, these results indicate that imidazole and imidazolium compounds derived from L-valine and L-phenylalanine—with different alkyl lengths in the amide substitution—can serve as potent antibacterial agents with low cytotoxicity to human cell lines. ; E.A.B. and S.G.M acknowledge funding from the Ministerio de Ciencia e Innovación (Spain) (PID2019-109333RB-I00) and the European Union's Horizon 2020 research and innovation program (Marie Skłodowska-Curie grant agreement No 845427). S.V.L and B.A. acknowledge funding from Ministerio de Ciencia e Innovación, RTI2018-098233-B-C22 and Pla de Promoció de la Investigació de la Universitat Jaume I, UJI-B2019-40. A.V. was funded by Ministerio de Ciencia e Innovación within the predoctoral fellowship program, grant FPU15/01191. ; Peer reviewed

D-amino acid oxidase (DAAO) plays an important role in the functioning of
both prokaryotes and eukaryotes. DAAO is increasingly being used in practice, including
for the determination of D-amino acids in complex samples, including human tissues
and fl uids. There are generally two types of DAAO in all organisms. The fi rst type is
an enzyme highly specifi c for D-aspartate and has its own name D-aspartate oxidase
(DASPO). DAAO of the second type is characterized by a wide spectrum of substrate
specificity, with preference for one or another D-amino acid varying from source to
source. The activity of DAAO with a large number of substrates greatly complicates the
selective determination of a particular D-amino acid. The problem is often solved by
choosing an enzyme that, under the conditions of analysis, has low or no activity with
other D-amino acids present in the sample. For the convenience of selecting a particular
enzyme, we have collected and analyzed literature data on the catalytic parameters
of known DAAOs with the most important D-amino acids. In addition, similar data
are presented for novel recombinant DAAOs from the methylotrophic yeast Ogataea
parapolymorpha DL-1. Analysis of the data shows that, with the D-amino acid series,
the new OpaDASPO and OpaDAAO have the highest catalytic parameters.

Nomenclature of Amino Acids -- The Protein Amino Acids -- Beta and Higher Homologous Amino Acids -- The Non-Protein Amino Acids -- Metabolic and Pharmacological Studies -- The Biosynthesis of Amino Acids in Plants -- Enzyme Inhibition by Amino Acids and their Derivatives -- Synthesis of Amino Acids -- Protected Amino Acids in Peptide Synthesis -- Resolution of Amino Acids -- Reactions of Amino Acids -- Degradation of Amino Acids Accompanying in vitro Protein Hydrolysis -- Racemization of Amino Acids -- Ion-Exchange Separation of Amino Acids -- Liquid Chromatography of Amino Acids and their Derivatives -- Gas-Liquid Chromatographic Separation of Amino Acids and their Derivatives -- Mass Spectrometry of Amino Acids and their Derivatives -- Nuclear Magnetic Resonance Spectra of Amino Acids and their Derivatives -- The Optical Rotatory Dispersion and Circular Dichroism of Amino Acids and their Derivatives -- Colorimetric and Fluorimetric Detection of Amino Acids -- Physical Properties of Amino Acid Solutions -- X-Ray Crystal Structures of Amino Acids and Selected Derivatives.

An ability to sense and respond to nutrient availability is an important requisite for life.Nutrient limitation is among main factors to influence the evolution of most cellular processes.Different pathways that sense intracellular and extracellular levels of carbohydtrates, amino acids,lipids, and intermediate metabolites are integrated and coordinated at the organismal levelthrough neuronal and humoral signals. During food abundance, nutrient-sensing pathwaysengage anabolism and storage, whereas limitation triggers the mechanisms, such as themobilization of internal stores including through autophagy. These processes are affected duringaging and are themselves important regulators of longevity, stress resistance, and age-relatedcomplications

Crickets (Gryllus bimaculatus De Geer) are considered a primary meat-alternative protein source. The insects comprise of 58 - 63% high-quality protein rich in essential amino acids. Nowadays, noodles are regularly consumed. Cricket powder-based protein noodles (PNCP) could be a choice for individuals with gluten allergies. In the present work, PNCP 0%, PNCP 15%, and PNCP 30% were assessed. PNCP 30% yielded the optimal nutritional quality in terms of moisture, ash, crude protein, crude fat, and crude fibre contents. It also contained the highest levels of 18 amino acids. Results also revealed that the noodles incorporated with cricket powder had double aspartic acid content, and increased proline content (3 - 7%) compared to control samples. Statistical analysis demonstrated a direct correlation between increased nutritional quality and the cricket powder amount added. Nevertheless, increasing cricket powder amount affected the colour of the resultant noodles. PNCP 30% yielded the darkest hue amongst the samples with an L* value of 38.21 ± 1.93%. Conversely, PNCP 0% and 15% samples yielded 56.18 ± 0.75 and 45.06 ± 1.66% L* values, respectively. Texture profile analysis also revealed the effects on the tensile strength values of enhancing the cricket powder content. Panellists scored the PNCP samples on a 9-point hedonic scale in a five-dimensional sensory evaluation. PNCP 15% recorded the ideal combination of palatability, appearance, and characteristics. Overall, the present work demonstrated that whilst utilising cricket powder as the alternative protein source in noodles is feasible, an accompanying sensory evaluation is critical to ensure that its incorporation does not compromise consumer acceptance of the final product.

Sorbtion of dipeptides leucylisoleucine, threonylthreonine and their monomeric amino acids leucine and threonine by anionite AV-17 and cationite KU-2-8 in a wide range of equilibrium concentrations has been studied. It was shown that the presence of hydrophilic OH-groups in the threonine molecule promotes superequivalent sorbtion of threonine on the cation exchanger. The presence of an OH-groups in the side chein of the dipeptide practically does not affect the sorbtion an KU-2-8. Sorbtion of dipeptides on AV-17-8 is higher in comparison with their monomeric amino acids.