Recent trends in the separation and analysis of chitooligomers.

Chitosan is a widely used linear biopolymer composed mainly of glucosamine and to a lesser extent of N-acetylglucosamine units. Many biological activities of chitosan are attributed to its shorter oligomeric chains, which consist of chitosan prepared either by enzyme activity (lysozyme, bacterial chitinase) or chemically by acid-catalyzed hydrolysis (e.g.

The variable structural flexibility of the Bacillus circulans β-galactosidase isoforms determines their unique functionalities.

β-Galactosidase from Bacillus circulans ATCC 31382 (BgaD) is a biotechnologically important enzyme for the synthesis of β-galactooligosaccharides (GOS). Among its four isoforms, isoform A (BgaD-A) has distinct synthetic properties. Here, we present cryoelectron microscopy (cryo-EM) structures of BgaD-A and compare them with the known X-ray crystal structure of isoform D (BgaD-D), revealing substantial structural divergences between the two isoforms.

New Bacterial Aryl Sulfotransferases: Effective Tools for Sulfation of Polyphenols.

The preparation of pure metabolites of bioactive compounds, particularly (poly)phenols, is essential for the accurate determination of their pharmacological profiles . Since the extraction of these metabolites from biological material is tedious and impractical, they can be synthesized enzymatically by bacterial PAPS-independent aryl sulfotransferases (ASTs). However, only a few ASTs have been studied and used for (poly)phenol sulfation.

Galectin-targeting glycocalix[4]arenes can enter the cells.

Elevated levels of galectin-3 are associated with tumorigenesis. Its inhibition with high-affinity carbohydrate ligands opens new therapeutic routes. Targeting of intracellular galectin-3 is challenging for polar inhibitors like carbohydrates.

Glycocalix[4]arenes and their affinity to a library of galectins: the linker matters.

Galectins are lectins that bind β-galactosides. They are involved in important extra- and intracellular biological processes such as apoptosis, and regulation of the immune system or the cell cycle. High-affinity ligands of galectins may introduce new therapeutic approaches or become new tools for biomedical research.

Sulfation of Phenolic Acids: Chemoenzymatic vs. Chemical Synthesis.

Phenolic acids are known flavonoid metabolites, which typically undergo bioconjugation during phase II of biotransformation, forming sulfates, along with other conjugates. Sulfated derivatives of phenolic acids can be synthesized by two approaches: chemoenzymatically by 3'-phosphoadenosine-5'-phosphosulfate (PAPS)-dependent sulfotransferases or PAPS-independent aryl sulfotransferases such as those from , or chemically using SO complexes. Both approaches were tested with six selected phenolic acids (2-hydroxyphenylacetic acid (2-HPA), 3-hydroxyphenylacetic acid (3-HPA), 4-hydroxyphenylacetic acid (4-HPA), 3,4-dihydroxyphenylacetic acid (DHPA), 3-(4-hydroxyphenyl)propionic acid (4-HPP), and 3,4-dihydroxyphenylpropionic acid (DHPP)) to create a library of sulfated metabolites of phenolic acids.

Mutation Hotspot for Changing the Substrate Specificity of β--Acetylhexosaminidase: A Library of GlcNAcases.

β--Acetylhexosaminidase from (Hex; EC 3.2.1.

Bacterial Aryl Sulfotransferases in Selective and Sustainable Sulfation of Biologically Active Compounds using Novel Sulfate Donors.

Regioselective sulfation of bioactive compounds is a vital and scarcely studied topic in enzyme-catalyzed transformations and metabolomics. The major bottleneck of enzymatic sulfation consists in finding suitable sulfate donors. In this regard, 3'-phosphoadenosine 5'-phosphosulfate (PAPS)-independent aryl sulfotransferases using aromatic sulfate donors are a favored choice due to their cost-effectiveness.

Sulfated Phenolic Substances: Preparation and Optimized HPLC Analysis.

Sulfation is an important reaction in nature, and sulfated phenolic compounds are of interest as standards of mammalian phase II metabolites or pro-drugs. Such standards can be prepared using chemoenzymatic methods with aryl sulfotransferases. The aim of the present work was to obtain a large library of sulfated phenols, phenolic acids, flavonoids, and flavonolignans and optimize their HPLC (high performance liquid chromatography) analysis.

Engineered Glycosidases for the Synthesis of Analogs of Human Milk Oligosaccharides.

Enzymatic synthesis is an elegant biocompatible approach to complex compounds such as human milk oligosaccharides (HMOs). These compounds are vital for healthy neonatal development with a positive impact on the immune system. Although HMOs may be prepared by glycosyltransferases, this pathway is often complicated by the high price of sugar nucleotides, stringent substrate specificity, and low enzyme stability.

Glycopolymers Decorated with 3--Substituted Thiodigalactosides as Potent Multivalent Inhibitors of Galectin-3.

Galectin-3 (Gal-3) participates in many cancer-related metabolic processes. The inhibition of overexpressed Gal-3 by, e.g.

Immunoprotective neo-glycoproteins: Chemoenzymatic synthesis of multivalent glycomimetics for inhibition of cancer-related galectin-3.

Galectin-3 plays a crucial role in cancerogenesis; its targeting is a prospective pathway in cancer diagnostics and therapy. Multivalent presentation of glycans was shown to strongly increase the affinity of glycoconjugates to galectin-3. Further strengthening of interaction with galectin-3 may be accomplished using artificial glycomimetics with apt aryl substitutions.

Sulfated Metabolites of Luteolin, Myricetin, and Ampelopsin: Chemoenzymatic Preparation and Biophysical Properties.

Authentic standards of food flavonoids are important for human metabolic studies. Their isolation from biological materials is impracticable; however, they can be prepared . Twelve sulfated metabolites of luteolin, myricetin, and ampelopsin were obtained with arylsulfotransferase from and fully characterized by high-performance liquid chromatography, MS, and NMR.

Plant Nitrilase Homologues in Fungi: Phylogenetic and Functional Analysis with Focus on Nitrilases in and .

Fungi contain many plant-nitrilase (NLase) homologues according to database searches. In this study, enzymes NitTv1 from and NitAb from were purified and characterized as the representatives of this type of fungal NLase. Both enzymes were slightly more similar to NIT4 type than to NIT1/NIT2/NIT3 type of plant NLases in terms of their amino acid sequences.

Transglycosidase activity of glycosynthase-type mutants of a fungal GH20 β-N-acetylhexosaminidase.

β-N-Acetylhexosaminidases (CAZy GH20, EC 3.2.1.

Mitochondrial Superoxide Production Decreases on Glucose-Stimulated Insulin Secretion in Pancreatic β Cells Due to Decreasing Mitochondrial Matrix NADH/NAD Ratio.

Glucose-stimulated insulin secretion (GSIS) in pancreatic β cells was expected to enhance mitochondrial superoxide formation. Hence, we elucidated relevant redox equilibria. Unexpectedly, INS-1E cells at transitions from 3 (11 m; pancreatic islets from 5 m) to 25 m glucose decreased matrix superoxide release rates (MitoSOX Red monitoring validated by MitoB) and HO (mitoHyPer, subtracting mitoSypHer emission).

Multidrug Resistance Modulation Activity of Silybin Derivatives and Their Anti-inflammatory Potential.

Silybin is considered to be the main biologically active component of silymarin. Its oxidized derivative 2,3-dehydrosilybin typically occurs in silymarin in small, but non-negligible amounts (up to 3%). Here, we investigated in detail complex biological activities of silybin and 2,3-dehydrosilybin optical isomers.

Regioselective 3-O-Substitution of Unprotected Thiodigalactosides: Direct Route to Galectin Inhibitors.

The synthesis of tailored bioactive carbohydrates usually comprises challenging (de)protection steps, which lowers synthetic yields and increases time demands. We present here a regioselective single-step introduction of benzylic substituents at 3-hydroxy groups of β-d-galactopyranosyl-(1→1)-thio-β-d-galactopyranoside (TDG) employing dibutyltin oxide in good yields. These glycomimetics act as inhibitors of galectins-human lectins, which are biomedically attractive targets for therapeutic inhibition in, for example, cancerogenesis.

Simple and Rapid HPLC Separation and Quantification of Flavonoid, Flavonolignans, and 2,3-Dehydroflavonolignans in Silymarin.

Herbal preparations from have been used since the fourth century BC in liver disease treatment and against numerous other pathologies. Consumption of silymarin containing drugs and food supplements continues to increase. Precise, fast, reliable, and complex determination of all components of silymarin preparations is paramount for assessing its pharmacological quality.

Biotransformation of Silymarin Flavonolignans by Human Fecal Microbiota.

Flavonolignans occur typically in (milk thistle) fruit extract, silymarin, which contains silybin, isosilybin, silychristin, silydianin, and their 2,3-dehydroderivatives, together with other minor flavonoids and a polymeric phenolic fraction. Biotransformation of individual silymarin components by human microbiota was studied ex vivo, using batch incubations inoculated by fecal slurry. Samples at selected time points were analyzed by ultrahigh-performance liquid chromatography equipped with mass spectrometry.

Acceptor Specificity of β--Acetylhexosaminidase from : A Rational Explanation.

Fungal β--acetylhexosaminidases, though hydrolytic enzymes in vivo, are useful tools in the preparation of oligosaccharides of biological interest. The β--acetylhexosaminidase from is remarkable in terms of its synthetic potential, broad substrate specificity, and tolerance to substrate modifications. It can be heterologously produced in in a high yield.

Genetic and Functional Diversity of Nitrilases in Agaricomycotina.

Nitrilases participate in the nitrile metabolism in microbes and plants. They are widely used to produce carboxylic acids from nitriles. Nitrilases were described in bacteria, Ascomycota and plants.

A novel enzymatic tool for transferring GalNAc moiety onto challenging acceptors.

The β-N-acetylhexosaminidase from Penicillium oxalicum (PoHex; EC 3.2.1.