Phosphinotripeptidic Inhibitors of Leucylaminopeptidases

Phosphinate pseudopeptide are analogs of peptides containing phosphinate moiety in a place of the amide bond. Due to this, the organophosphorus fragment resembles the tetrahedral transition state of the amide bond hydrolysis. Additionally, it is also capable of coordinating metal ions, for example, zinc or magnesium ions. These two properties of phosphinate pseudopeptides make them an ideal candidate for metal-related protease inhibitors. This research investigates the influence of additional residue in the P2 position on the inhibitory properties of phosphinopeptides. The synthetic strategy is proposed, based on retrosynthetic analysis. The N-C-P bond formation in the desired compounds is conveniently available from the three-component condensation of appropriate amino components, aldehydes, and hypophosphorous acid. One of the crucial synthetic steps is the careful selection of the protecting groups for all the functionals. Determination of the inhibitor activity of the obtained compounds has been done using UV-Vis spectroscopy and standard substrate L-Leu-p-nitroanilide toward the enzymes isolated from the porcine kidney (SsLAP, Sus scrofa Leucine aminopeptidase) and barley seeds (HvLAP, Hordeum vulgare Leucine aminopeptidase). An efficient procedure for the preparation of phosphinotripeptides has been performed. Activity test shown that introduction of additional residue into P2 position obtains the micromolar range inhibitors of SsLAP and HvLAP. Moreover, careful selection of the residue in the P2 position should improve its selectivity toward mammalian and plant leucyl aminopeptidases.This research was funded by the Polish Ministry of Science and Higher Education (PMSHE) for the Faculty of Chemistry of Wrocław University of Science and Technology and by Wroclaw Research Center EIT+ under the project “Biotechnologies and advanced medical technologies—BioMed”, grant number POIG 01.01.02-02-003/08-00, 00 financed from the European Regional Development Fund (Operational Programme Innovative Economy, 1.1.2. B. O. is recipient of a Ph.D. fellowship from a project funded by the European Social Found. Financial support by the Ministerio de Ciencia, Innovación y Universidades (MCIU), Agencia Estatal de Investigación (AEI) y Fondo Europeo de Desarrollo Regional (FEDER) (RTI2018-101818-B-I00, UE), and Gobierno Vasco (GV), (IT 992-16) is gratefully acknowledged

Influence of ΔPhe residues on Conformation of peptide chain

In the past few years dehydropeptides have been highly investigated, mainly due to their biological activity: for instance, as antimicrobials or catalytic agents in some enzymes [1, 51-53]. In presented studies it was established that dehydrophenylalanine residue (ΔPhe) can be an interesting building block of various peptide chains, in order to control and modify a structure, conformation and function of the target molecule [3, 4, 5-7]. It was also pointed out that the length of a linker between dehydroamino acid residues (if two or more are present in a peptide chain) is a crucial factor in case of conformational dependence [23]. Short, one-residue spacers promote 310-helical structure, while longer ones increase the coexistence of 310-helical and α-helical conformers (Table 7). What is worth to notice, temperature or polarity of solvent can dramatically change the screw sense of obtained 310-helices (Table 11). Additionally, the screw sense can be altered by other variables, like chirality of C and N-terminus or dehydroamino acid isomer type (E or Z) [4-11]. Considering chain conformation, it can be disparate, depending on environment’s solid or liquid state (Table 7). Application of dehydropeptides is widely spread among assorted field of studies. As they can form a few self-assembled structures (e.g. nanotubes, nanovesicles or hydrogels), arise an opportunity of encapsulation of small drug molecules or trapping and releasing bioactive substances [47-49]. Sequences with incorporated dehydroamino acid residues were examined as a potential drug - interaction with negatively charged membrane of bacteria species is possible by virtue of positive polarization of peptide chain [51]. Part of the sequences exert an activity against E. coli, S. aureus, P. falciparum or highly dangerous MRSA, presenting versatile potential correlated with their secondary structure [50-53]

Biological activity of surfactins - a case of a biosurfactant produced by Bacillus subtilis PCM 1949

Biosurfactants are microbial surface active compounds which, contrary to synthetic surfactants, are natural in origin, biodegradable and less toxic to a human organism. For that reason, there is a great research potential in studies aimed at their purification, finding potential ways of their utilization and decreasing their production costs. This paper demonstrates the process of isolating and purifying a surfactin synthesized by Bacillus subtilis PCM 1949. Surfactin samples were prepared by a classical organic solvent extraction and were studied using mass spectrometry (MS). Analysis of the susceptibility profile of microorganisms utilized in the diffusion-plate tests demonstrated that their sensitivity to this surfactin is differentiated and depends on the microorganism species. In our studies, we found that the selected strains of bacteria and fungi were insensitive to this surfactin at a wide range of concentrations

Peptidomimetics and aromatic foldamers in biological chemistry

The interests of the research group working under the supervision of professor Rafał Latajka at the Department of Bioorganic Chemistry at the Wrocław University of Science and Technology are focused on several projects in the field of biological chemistry. Regardless of whether a given project concerns – the synthesis and activity of new enzyme inhibitors, peptides, peptidomimetics, or aromatic foldamers – the thread of correlation between the structure and activity of the studied systems always plays a pivotal role. In this article we are presenting current projects in our research group

Conformation of dehydropentapeptides containing four achiral amino acid residues – controlling the role of L-valine

Structural studies of pentapeptides containing an achiral block, built from two dehydroamino acid residues (ΔZPhe and ΔAla) and two glycines, as well as one chiral L-Val residue were performed using NMR spectroscopy. The key role of the L-Val residue in the generation of the secondary structure of peptides is discussed. The obtained results suggest that the strongest influence on the conformation of peptides arises from a valine residue inserted at the C-terminal position. The most ordered conformation was found for peptide Boc-Gly-ΔAla-Gly-ΔZPhe-Val-OMe (3), which adopts a right-handed helical conformation

Peptide stapling by late-stage Suzuki–Miyaura cross-coupling

Gruß H, Feiner R, Mseya R, et al. Peptide stapling by late-stage Suzuki–Miyaura cross-coupling. Beilstein Journal of Organic Chemistry. 2022;18:1-12.The development of peptide stapling techniques to stabilise α-helical secondary structure motifs of peptides led to the design of modulators of protein–protein interactions, which had been considered undruggable for a long time. We disclose a novel approach towards peptide stapling utilising macrocyclisation by late-stage Suzuki–Miyaura cross-coupling of bromotryptophan-containing peptides of the catenin-binding domain of axin. Optimisation of the linker length in order to find a compromise between both sufficient linker rigidity and flexibility resulted in a peptide with an increased α-helicity and enhanced binding affinity to its native binding partner β-catenin. An increased proteolytic stability against proteinase K has been demonstrated

Tripeptides conjugated with thiosemicarbazones: new inhibitors of tyrosinase for cosmeceutical use

AbstractThe development of skin-care products is recently growing. Cosmetic formulas containing active ingredients with proven efficacy, namely cosmeceuticals, are based on various compounds, including peptides. Different whitening agents featuring anti-tyrosinase activity have been applied in the cosmeceutical field. Despite their availability, their applicability is often limited due to several drawbacks including toxicity, lack of stability, and other factors. In this work, we present the inhibitory effect on diphenolase activity of thiosemicarbazone (TSC)-peptide conjugates. Tripeptides FFY, FWY, and FYY were conjugated with three TSCs bearing one or two aromatic rings via amide bond formation in a solid phase. Compounds were then examined as tyrosinase and melanogenesis inhibitors in murine melanoma B16F0 cell line, followed by the cytotoxicity assays of these cells. In silico investigations explained the differences in the activity, observed among tested compounds. Mushroom tyrosinase was inhibited by TSC1-conjugates at micromolar level, with IC50 lower than this for kojic acid, a widely used reference compound. Up to now, this is the first report regarding thiosemicarbazones conjugated with tripeptides, synthesised for the purpose of tyrosinase inhibition

Design, synthesis, conformational analysis, and biological activity of Cα1-to-Cα6 1,4- and 4,1-disubstituted 1H-[1,2,3]triazol-1-yl-bridged oxytocin analogues

AbstractOxytocin (OT) is a neurohypophyseal peptide hormone containing a disulphide-bridged pseudocyclic conformation. The biomedical use of OT peptides is limited amongst others by disadvantageous pharmacokinetic parameters. To increase the stability of OT by replacing the disulphide bridge with the stable and more rigid [1,2,3]triazol-1-yl moiety, we employed the Cu2+-catalysed side chain-to-side chain azide-alkyne 1,3-cycloaddition. Here we report the design, synthesis, conformational analysis, and in vitro pharmacological activity of a homologous series of Cα1-to-Cα6 side chain-to-side chain [1,2,3]triazol-1-yl-containing OT analogues differing in the length of the bridge, location, and orientation of the linking moiety. Exploiting this macrocyclisation approach, it was possible to generate a systematic series of compounds providing interesting insight into the structure-conformation-function relationship of OT. Most analogues were able to adopt similar conformation to endogenous OT in water, namely, a type I β-turn. This approach may in the future generate stabilised pharmacological peptide tools to advance understanding of OT physiology