Ceramide synthases (CerSs) play crucial roles in sphingolipid metabolism and have emerged as promising drug targets for metabolic diseases, cancers, and antifungal therapy. However, the therapeutic targeting of CerSs has been hindered by a limited understanding of their inhibition mechanisms by small molecules. Fumonisin B1 (FB1) has been extensively studied as a potent inhibitor of eukaryotic CerSs. In this study, we characterize the inhibition mechanism of FB1 on yeast CerS (yCerS) and determine the structures of both FB1-bound and N-acyl-FB1-bound yCerS. Through our structural analysis and the observation of N-acylation of FB1 by yCerS, we propose a potential ping-pong catalytic mechanism for FB1 N-acylation by yCerS. Lastly, we demonstrate that FB1 exhibits lower binding affinity for yCerS compared to the C26- coenzyme A (CoA) substrate, suggesting that the potent inhibitory effect of FB1 on yCerS may primarily result from the N-acyl-FB1 catalyzed by yCerS, rather than through direct binding of FB1.

This paper describes a unified approach toward diglycosylamines using methanolic ammonia. All the glycosylamines prepared have been fully characterized, and their anomeric configuration has been determined. The article presents a novel method for the N-acylation of diglycosylamines and other electron-poor glycosylamines, which employs nitromethane as a solvent in carboxylic anhydride acylation under acidic conditions. The feasibility of this transformation is represented by a wide range of reaction substrates. All glycosylamides are formed solely with β-configuration. These two reactions constitute a simple and effective route to the synthesis of a novel class of compounds with an N-glycosidic linkage.

The aim of the present work was to obtain microbial lipids (single-cell oils and SCOs) from oleaginous yeast cultivated on biodiesel-derived glycerol and subsequently proceed to the enzymatic synthesis of high-value biosurfactant-type molecules in an aqueous medium, with SCOs implicated as acyl donors (ADs). Indeed, the initial screening of five non-conventional oleaginous yeasts revealed that the most important lipid producer was the microorganism Cryptococcus curvatus ATCC 20509. SCO production was optimised according to the nature of the nitrogen source and the initial concentration of glycerol (Glyc0) employed in the medium. Lipids up to 50% w/w in dry cell weight (DCW) (SCOmax = 6.1 g/L) occurred at Glyc0 ≈ 70 g/L (C/N ≈ 80 moles/moles). Thereafter, lipids were recovered and were subsequently used as ADs in the N-acylation reaction catalysed by aminoacylases produced from Streptomyces ambofaciens ATCC 23877 under aqueous conditions, while Candida antarctica lipase B (CALB) was used as a reference enzyme. Aminoacylases revealed excellent activity towards the synthesis of acyl-lysine only when free fatty acids (FAs) were used as the AD, and the rare regioselectivity in the α-amino group, which has a great impact on the preservation of the functional side chains of any amino acids or peptides. Aminoacylases presented higher α-oleoyl-lysine productivity and final titer (8.3 g/L) with hydrolysed SCO than with hydrolysed vegetable oil. The substrate specificity of both enzymes towards the three main FAs found in SCO was studied, and a new parameter was defined, viz., Specificity factor (Sf), which expresses the relative substrate specificity of an enzyme towards a FA present in a FA mixture. The Sf value of aminoacylases was the highest with palmitic acid in all cases tested, ranging from 2.0 to 3.0, while that of CALB was with linoleic acid (0.9-1.5). To the best of our knowledge, this is the first time that a microbial oil has been successfully used as AD for biosurfactant synthesis. This bio-refinery approach illustrates the concept of a state-of-the-art combination of enzyme and microbial technology to produce high-value biosurfactants through environmentally friendly and economically sound processes.

The paper describes the formation of six aromatic N-(2-arylethyl)-2-methylprop-2-enamides with various substituents in benzene ring, viz., 4-F, 4-Cl, 2,4-Cl2, 4-Br, 4-OMe, and 3,4-(OMe)2 from 2-arylethylamines and methacryloyl chloride in ethylene dichloride with high yields (46-94%). The structure of the compounds was confirmed by 1H NMR, 13C NMR, IR, and HR-MS. Those compounds were obtained to serve as functionalized templates for the fabrication of molecularly imprinted polymers followed by the hydrolysis of an amide linkage. In an exemplary experiment, the imprinted polymer was produced from N-(2-(4-bromophenyl)ethyl)-2-methylprop-2-enamide and divinylbenzene, acting as cross-linker. The hydrolysis of 2-(4-bromophenyl)ethyl residue proceeded and the characterization of material including SEM, EDS, 13C CP MAS NMR, and BET on various steps of preparation was carried out. The adsorption studies proved that there was a high affinity towards the target biomolecules tyramine and L-norepinephrine, with imprinting factors equal to 2.47 and 2.50, respectively, when compared to non-imprinted polymer synthesized from methacrylic acid and divinylbenzene only.

The selective acylation of indoles often requires sensitive and reactive acyl chloride derivatives. Here, we report a mild, efficient, functional group tolerant, and highly chemoselective N-acylation of indoles using thioesters as a stable acyl source. A series of indoleamides have been obtained with moderate to good yields. In addition, heterocycles, such as carbazole, can also be used as nucleophiles in this reaction.

Lipopeptides represent a large group of microbial natural products that include important antibacterial and antifungal drugs and some of the most-powerful known biosurfactants. The vast majority of lipopeptides comprise cyclic peptide backbones N-terminally equipped with various fatty acyl moieties. The known compounds of this type are biosynthesized by nonribosomal peptide synthetases, giant enzyme complexes that assemble their products in a non-gene-encoded manner. Here, we report the genome-guided discovery of ribosomally derived, fatty-acylated lipopeptides, termed selidamides. Heterologous reconstitution of three pathways, two from cyanobacteria and one from an arctic, ocean-derived alphaproteobacterium, allowed structural characterization of the probable natural products and suggest that selidamides are widespread over various bacterial phyla. The identified representatives feature cyclic peptide moieties and fatty acyl units attached to (hydroxy)ornithine or lysine side chains by maturases of the GCN5-related N-acetyltransferase superfamily. In contrast to nonribosomal lipopeptides that are usually produced as congener mixtures, the three selidamides are selectively fatty acylated with C10, C12, or C16 fatty acids, respectively. These results highlight the ability of ribosomal pathways to emulate products with diverse, nonribosomal-like features and add to the biocatalytic toolbox for peptide drug improvement and targeted discovery.

Viral outbreaks are a common cause of morbidity and mortality in livestock and human populations. Lack of good vaccines and poor control measures along with natural viral genetic drifting and shifting are the common causes of new viral strains and outbreaks. The current study reports the synthesis of some 2-aryl substituted thiazolidine-4-carboxylic acids 1a-h and their 3-acetyl 2a and 3-benzoyl derivatives 3a. Two important poultry viruses: Avian influenza virus (AIV; A/Chicken/Italy/1994/H9N2) and infectious bronchitis virus (IBV) were selected, grown in ‎9-11 days old chicken embryonated eggs‎, and subjected to in ovo anti-viral assays. Most of the synthesized compounds were found active against AIV subtype H9N2 and IBV. In the case of AIV, the best results were attained for compound 1d which showed an IC50 value of 3.47 µM, while IBV 1c showed IC50 value of 4.10 µM. The lower IC50 values of these compounds correlate with the high potency of these compounds, especially in comparison with control groups. The standard drugs amantadine and ribavarin were used as positive controls in the case of AIV and IBV, respectively. Better results were obtained with 2-aryl substituted thiazolidine-4-carboxylic acids 1a-h compared to their N-acylated derivatives 2a and 3a against both viruses. In conclusion, this preliminary data support the idea that thiazolidine carboxylic acids could be used as anti-viral drugs against AIV and IBV infections.

The majority of enzymes in the sphingolipid (SL) biosynthetic pathway have been identified over the past couple of decades. Despite significant work, and despite their crucial and central roles in SL synthesis, significant information is still lacking concerning the enzymes that catalyze the N-acylation of sphingoid long chain bases, namely the ceramide synthases (CerS), a family of six mammalian genes originally named longevity assurance (Lass) genes. Each of these six endoplasmic reticulum (ER) membrane-bound enzymes utilizes a relatively restricted sub-set of fatty acyl-CoAs for N-acylation, but are far more promiscuous about the use of long chain bases. The reason that mammals and other species have multiple CerS, generating a specific subset of ceramides, is not yet known, but implies an important role for ceramides containing specific fatty acids in cell physiology. In this brief chapter, we will stroll down the CerS lane and discuss what is known, and what is not known, about this important enzyme family.

Oligonucleotides carrying a variety of chemical modifications including conjugates are finding increasing applications in therapeutics, diagnostics, functional genomics, proteomics, and as research tools in chemical and molecular biology. The successful synthesis of oligonucleotides primarily depends on the use of appropriately protected nucleoside building blocks including the exocyclic amino groups of the nucleobases, the hydroxyl groups at the 2\'-, 3\'-, and 5\'-positions of the sugar moieties, and the internucleotide phospho-linkage. This unit is a thoroughly revised update of the previously published version and describes the recent development of various protecting groups that facilitate reliable oligonucleotide synthesis. In addition, various protecting groups for the imide/lactam function of thymine/uracil and guanine, respectively, are described to prevent irreversible nucleobase modifications that may occur in the presence of reagents used in oligonucleotide synthesis. © 2017 by John Wiley & Sons, Inc.

Ceramides are synthesized by six mammalian ceramide synthases (CerSs), each of which uses fatty acyl-CoAs of different chain lengths for N-acylation of the sphingoid long-chain base. We now describe a rapid and reliable CerS assay that uses a fluorescent N-[6-[(7-nitrobenzo-2-oxa-1,3-diazol-4-yl) (NBD) sphinganine substrate followed by separation of the NBD-lipid substrate and products using solid phase extraction (SPE) C18 chromatography. SPE chromatography is a quick and reliable alternative to TLC, and moreover, there is no degradation of either NBD-sphinganine or NBD-ceramide. We have optimized the assay for use with minimal amounts of protein in a minimal volume. This assay will prove useful for the analysis of CerS activity, which is of particular importance in light of the growing involvement of CerS in cell regulation and in the pathology of human diseases.