Search

Peptides conjugated with organic molecules can be useful tools for the development of novel bioactive compounds. The lysine side‐chain is an interesting functional group to act as a linker to connect small molecules in peptide conjugates. Herein we present the design and synthesis of four Safirinium derivatives, their facile conjugation to lysine in solid phase, and incorporation in peptides. The compounds differing in the functionalization of nitrogen N2 of the condensed triazolyl moiety are novel building blocks to design conjugates to perform structure‐activity relationship studies of elastase inhibitors. Consequently, structural investigations of the lysine building blocks and of the corresponding peptide conjugates were performed. We present herein the potential of the Safirinium analogs to act as elastase inhibitors in assays performed on porcine pancreas elastase. [ABSTRACT FROM AUTHOR]

On December 12th, 2023, the European Commission took regulatory action to amend Annex XVII of REACH, imposing restrictions on the use of N,N‐dimethylformamide (DMF) within the EU market owing to its high toxicity. Historically, DMF has been widely considered the gold standard for solid‐phase peptide synthesis (SPPS). Being urgent to propose alternative solvents, we tested the suitability of non‐hazardous neat and mixed solvents. Notably, binary solvent mixtures containing dimethyl sulfoxide as one of the solvent partners demonstrated high efficacy in solubilizing reagents while maintaining the desired swelling characteristics of common resins. A series of binary solvent mixtures were tested in automated SPPS, both at room temperature and high temperature, employing the PurePep® Chorus synthesizer, which enabled controlled induction heating between 25 and 90°C with oscillation mixing. The performances were assessed in challenging peptide sequences, i.e., ACP (65–74), and in longer and aggregating sequences like SARS‐CoV‐2 RBM (436–507) and β‐amyloid (1–42). Furthermore, as part of the proposed sustainable approach to minimize the utilization of hazardous solvents, we coupled the novel PurePep EasyClean catch‐and‐release purification technology. This work, addressing regulatory compliance, emphasizes the crucial role of green chemistry in advancing safer and more environmentally friendly practices in SPPS. [ABSTRACT FROM AUTHOR]

In recent years, there has been increasing interest in developing novel materials based on natural biopolymers as a renewable alternative to petroleum-based plastics. The availability of proteins derived from agricultural by-products, along with their favourable properties, has fostered a renewed interest in protein-based materials, promoting research in innovative technologies. In this study, we propose the use of rapeseed protein-rich meal as the main ingredient for the preparation of novel sustainable materials combining excellent environmental properties such as biodegradability and renewability. The application of sustainable products in the present high-tech society requires the modification of the basic native properties of these natural compounds. The original route proposed in this paper consists of preparation via the compression moulding of flexible biomaterials stabilized by crosslinkers/chain extenders. An investigation of the effects of different denaturing and disulfide bond reducing agents, crosslinkers, and preparation conditions on the material mechanical behaviour demonstrated that the novel materials have appreciable strength and stiffness. The results show the potential of utilizing full meal from vegetable by-products to prepare protein-based materials with guaranteed ecofriendly characteristics and mechanical properties adequate for specific structural applications. [ABSTRACT FROM AUTHOR]

Argireline (Ac‐EEMQRR‐NH2), a well‐known neurotransmitter peptide with a potency similar to botulinum neurotoxins, reveals a proven affinity toward Cu(II) ions. We report herein Cu(II) chelating properties of three new Argireline derivatives, namely, AN4 (Ac‐EAHRR‐NH2), AN5 (Ac‐EEHQRR‐NH2), and AN6 (Ac‐EAHQRK‐NH2). Two complementary experimental techniques, i.e., potentiometric titration (PT) and isothermal titration calorimetry (ITC), have been employed to describe the acid–base properties of the investigated peptides as well as the thermodynamic parameters of the Cu(II) complex formation. Additionally, based on density functional theory (DFT) calculations, we propose the most likely structures of the resulting Cu‐peptide complexes. Finally, the cytotoxicity of the free peptides and the corresponding Cu(II) complexes was estimated in human skin cells for their possible future cosmetic application. The biological results were subsequently compared with free Argireline, its Cu(II)‐complexes, and the previously studied AN2 derivative (EAHQRR). [ABSTRACT FROM AUTHOR]

The standard GAFF2 force field parameterization has been refined for the fluorinated alcohols 2,2,2‐trifluoroethanol (TFE), 1,1,1,3,3,3‐hexafluoro‐2‐propanol (HFIP), and 1,1,1,3,3,3‐hexafluoropropan‐2‐one (HFA), which are commonly used to study proteins and peptides in biomimetic media. The structural and dynamic properties of both proteins and peptides are significantly influenced by the biomimetic environment created by the presence of these cosolvents in aqueous solutions. Quantum mechanical calculations on stable conformers were used to parameterize the atomic charges. Different systems, such as pure liquids, aqueous solutions, and systems formed by melittin protein and cosolvent/water solutions, have been used to validate the new models. The calculated macroscopic and structural properties are in agreement with experimental findings, supporting the validity of the newly proposed models. [ABSTRACT FROM AUTHOR]

To date, the severe acute respiratory syndrome coronavirus‐2 (SARS‐CoV‐2) COVID‐19 pandemic continues to be a potentially lethal disease. Although both vaccines and specific antiviral drugs have been approved, the search for more specific therapeutic approaches is still ongoing. The infection mechanism of SARS‐CoV‐2 consists of several stages, and each one can be selectively blocked to disrupt viral infection. Peptides are a promising class of antiviral compounds, which may be suitably modified to be more stable, more effective, and more selective towards a specific viral replication step. The latter two goals might be obtained by increasing the specificity and/or the affinity of the interaction with a specific target and often imply the stabilization of the secondary structure of the active peptide. This review is focused on modified antiviral peptides against SARS‐CoV‐2 acting at different stages of virus replication, including ACE2‐RBD interaction, membrane fusion mechanism, and the proteolytic cleavage by different viral proteases. Therefore, the landscape presented herein provides a useful springboard for the design of new and powerful antiviral therapeutics. [ABSTRACT FROM AUTHOR]

Oxytocin (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. [ABSTRACT FROM AUTHOR]

The 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. [ABSTRACT FROM AUTHOR]

Multiple sclerosis (MS) is an inflammatory and autoimmune disorder, in which an antibody‐mediated demyelination mechanism plays a critical role. We prepared two glucosylated peptides derived from the human myelin proteins, that is, oligodendrocyte‐myelin glycoprotein (OMGp) and reticulon‐4 receptor (RTN4R), selected by a bioinformatic approach for their conformational homology with CSF114(Glc), a designed β‐turn antigenic probe derived from myelin oligodendrocyte glycoprotein (MOG), a glycoprotein present in the CNS. This synthetic antigen is specifically recognized by antibodies in sera of MS patients. We report herein the antigenic properties of these peptides, showing, on the one hand, that MS patient antibodies recognize the two glucosylated peptides and, on the other hand, that these antibodies cross‐react with CSF114(Glc) and with the previously described hyperglucosylated nontypeable Haemophilus influenzae bacterial adhesin protein HMW1ct(Glc). These observations point to an immunological association between human and bacterial protein antigens, underpinning the hypothesis that molecular mimicry triggers the breakdown of self‐tolerance in MS and suggesting that RTN4R and OMGp can be considered as autoantigens. [ABSTRACT FROM AUTHOR]