We describe a non-chromatographic, ligand-free platform for the efficient purification of recombinant human lactoferrin. The platform consists of a [metal:chelator] complex precipitate in the presence of osmotically active polyethylene glycol 6000 . Purification is achieved in three stages. Following formation of the complex, LF is captured under neutral conditions by the aggregated complexes (Step I), a washing step follows (Step II) and then, (Step III) LF is extracted in pure form with 100 mM tribasic Na citrate buffer (pH 7). Of the four complexes investigated, [bathophenanthroline (batho)3:Fe2+] was determined to be the most efficient. LF is recovered with high yield (~90%) and purity (≥97%, by SDS polyacrylamide gel electrophoresis ) from an artificial contamination background comprising E. coli lysate proteins. Purified LF is demonstrated to be monomeric by dynamic light scattering ; to preserve its native secondary structure by circular dichroism spectroscopy; and, as apo-LF, to efficiently inhibit bacterial growth. Process yield is not
affected by a 45-fold increase in LF concentration from 0.2 to 9 mg/mL. We provide evidence that protein
capture relies on [cation:π] interactions between the lysine and arginine residues of LF with the fully aromatic
[(batho)3:Fe2+] complexes. The use of [metal:chelator] complex aggregates is demonstrated to provide an
economical and efficient avenue for LF purification.

Nanotechnologies have garnered significant attention in the scientific community due to their applications in various areas of medicine. In particular, silvernanoparticles(Ag-NPs) are noteworthy for their antibacterial and surface plasmonic properties, which depend on their shape anisotropy. Understanding the interactions of Ag-NPs with biomolecules in biological systems is essential for the safe use of new treatments involving these materials. For this reason, we study serum albumin(BSA), the most abundant protein in blood, which plays key roles such as regulating pH, solubilizing certain drugs, and transporting pharmaceutical agents. Examining the behavior of nanoparticles with albumin (Ag-NPs/BSA) can provide valuable insights into their pharmacological effects.[1]

In this work, we've confirmed that the presence of prism-shapedAg-NPs and sphericalAg-NPs induces changes in the protein structure, that include aggregation. The technologies used include FourierTransformInfraredSpectroscopy(FT-IR), Small-AngleX-RayScattering(SAXS), and Transmission Electron Microscopy(TEM) to study these interactions

FTIR results have shown slight differences between the BSA spectrum and the Ag-NPs spectrum in band shape, indicating minimal interaction. In contrast, XAS results have revealed strong attractive interactions leading to aggregation. Finally, TEM confirmed the aggregation of nanoparticles in the presence of BSA. [2]

[1] http://dx.doi.org/10.1016/j.molliq.2016.02.103

[2] http://dx.doi.org/10.1016/j.cbi.2016.05.018

The growth hormone secretagogue receptor 1a (GHSR), known as the ghrelin receptor, is differentially expressed in various diseases and cancer types, including pancreatic, breast, and prostate.¹ A ghrelin-based analogue was previously discovered with exceptional receptor affinity, however, in vivo evaluation revealed an unfavourable pharmacokinetics with rapid clearance and accumulation in the liver and intestines.² Stability investigations revealed a metabolic soft spot between amino acids Leu⁵ and Ser⁶.³ Subsequently, a library of analogues were synthesized and evaluated for their in vitro stability, revealing two analogues with improved metabolic stability with retained receptor affinity. In this investigation, three analogues are being radiolabelled with a fluorine-18 6-fluoro-2-naphtyl (6-FN) prosthetic group and evaluated in vivo to assess their pharmacokinetic profiles. Peptides were synthesized using Fmoc solid-phase peptide synthesis, purified by preparative HPLC, and characterized by high-resolution mass spectrometry. An iodonium ylide precursor was synthesized and radiolabelled with fluorine-18 to yield the ¹⁸F-prosthetic group, which was then conjugated to the peptides. The probes are being evaluated in a prostate cancer xenograft model to assess varying pharmacokinetic profiles. This study demonstrates the intricate radiopharmaceutical optimization pathway, accounting for affinity, stability and biodistribution, towards the development of a peptide-based ghrelin-targeted PET probe for prostate cancer imaging.

Peptide alkyl thioesters are versatile reagents in various synthetic applications, commonly generated from peptide hydrazides and thiols. However, a notable limitation is the need for a substantial excess of the thiol reagent, restricting the usage to simple thiols.[1] This limitation confines these synthetic strategies to the production of thioesters from economical and thus relatively simple thiol nucleophiles.

Here, we introduce an adapted procedure that significantly enhances thioester production with just a minimal thiol excess, facilitating the use of advanced thiol nucleophiles.[2] Indeed, following a procedure reported by Liu and colleagues, the hydrazide initially undergoes activation with sodium nitrite to yield a peptide azide. Subsequently, an excess of aryl thiol is added to the peptide azide solution under neutral pH conditions, resulting in the formation of an intermediate aryl thioester.

In our method, an additional step involves a thiol-thioester exchange between the in situ formed aryl thioester and an alkyl thiol added in quasi-stoichiometric amounts to the reaction, under conditions enabling to concomitantly remove the excess of aryl thiol.

This was conveniently achieved by using p-hydroxythiophenol, a thiol extractable under neutral pH conditions. Our method has proven highly effective in accessing peptide thioesters from a variety of alkyl thiols.

Beta-casomorphin-7 (BCM-7), released from β-casein A1 during digestion, has been identified as a potential risk factor for health issues, including chronic inflammation, gastrointestinal discomfort, and possible influences on neurological conditions. Reducing its release in dairy products has become a priority in the development of safer functional foods. This study investigated the impact of whole milk fermented with Lacticaseibacillus casei LBC 237 and Limosilactobacillus fermentum 433 on BCM-7 release. Fermentations were conducted separately at 37°C for 16 hours, followed by centrifugation and simulated digestion in the gastric and intestinal phases. ELISA tests indicated an initial absorbance of 0.196 and 0.210 in the fermented samples for L. casei and L. fermentum, respectively; these values dropped to 0.070 and 0.075 after digestion. Although in vitro digestion reduced the concentration of BCM-7 in fermented milk samples, fermentation with L. casei and L. fermentum did not demonstrate an additional significant reduction in the concentration of this peptide compared to non-fermented samples. The results suggest that fermentation conditions were insufficient for effective BCM-7 degradation. The study continues to explore the use of additional enzymes to improve BCM-7 degradation in dairy products.

COVID-19, an infectious respiratory disease caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), has led to a global pandemic with profound public health implications and significant economic impacts worldwide. The Type-II transmembrane serine protease (TMPRSS2) has been identified as the proteolytic driver of SARS-CoV-2 activation and replication, making the dysregulation of TMPRSS2 activity a highly effective host-directed therapeutic strategy.

The previously reported TMPRSS2 inhibitor N-0385 exhibits unfavorable pharmacokinetic properties, including excessively high bioavailability (99%). To address the issue of significant systemic exposure, we designed a small library of peptidomimetic compounds with P3 site modifications by substituting proteinogenic amino acids and further evaluated their potency, in vitro efficacy, and pharmacokinetic profiles.

Exceptionally, compound 9, with Asp at the P3 position, resulted in a 2-fold increase in TMPRSS2 sub-nanomolar inhibitory potency (Ki of 13 ± 0.03 nM), while achieving >700-fold selectivity over Factor Xa and a superior selectivity profile against other proteases (matriptase, TMPRSS6, thrombin, and furin). An in vitro air-liquid interface (ALI) model of pulmonary epithelium revealed that compound 9 demonstrated a 1.5-fold decrease in permeability compared to N-0385, with sustained lung (11 h) and plasma (13 h) stability, suggesting its potential for daily prophylactic or therapeutic intranasal administration.

Penicillin-binding protein 2a (PbP 2a) expression accounts for the insusceptibility of methicillin-resistant Staphylocuccus aureus (MRSA) to β-lactam antibiotics. In this research, we employed computational strategies to challenge PbP 2a with series of fifty-five ‘ala-ala’ and ‘ala-pro’ sulphonamide-dipeptides. The binding stability of two compounds (labeled: 10i and 10n) with theoretical Ki in nM and μM ranges, for PbP 2a active and allosteric sites respectively, were investigated using molecular dynamics simulations. In addition, the results of the sensitivity of four strains of MRSA for compounds 10i and 10n obtained revealed the compounds at 10 μg/ml caused two isolates (S4 and S10) to revert to being susceptible. Finally, a reliable binding conformation of both compounds in the two binding sites of PbP 2a are described to provide a rationale for structure-activity optimization of this series.

Cryptococcosis is an opportunistic infection caused by Cryptococcus neoformans that mainly affects HIV patients. Increased resistance and new strain emergence make necessary new antifungals, like short peptides. In this work, three short peptides (P1, P2, and P3) were synthesized by solid phase synthesis (SPPS) and tested as potential antifungal agents against clinical strains of the species C. neoformans.

Peptides were synthesized using Fmoc chemistry on Rink-Amide-methylbenzhydrylamine (MBHA) resin in SPPS. Petri dishes were prepared with Mueller Hinton medium and the inoculum of C. neoformans was seeded with each strain to be tested, making holes into which 15 µL of each peptide at different concentrations were inoculated. The plates were incubated for 48 hours at 28°C.

The three peptides presented antifungal activity against the C. neoformans species, with inhibition zones observed in all studies for the highest peptide concentrations. P2 showed the greatest inhibition, with halos observed at the peptide concentration of 0.512 mg/mL, while P1 and P3 presented inhibition at a concentration of 2.5 mg/mL.

Peptides proved to be an interesting alternative in the search for new antifungals since they present advantages such as less development of resistance^1,2 compared to commercial antifungals.

Peptide and protein hydrogels are innovative biomaterials that have garnered significant attention in biomedical applications. Both types of these hydrogels exhibit unique biological properties that make them suitable for various applications, particularly in tissue engineering and 3D bioprinting. Despite their advantages, issues such as stability, reproducibility, and clinical translation remain significant hurdles for the development and application of such hydrogels. Patent analysis can provide valuable insights into emerging technologies, trends, and opportunities for innovation in the field of development and application of hydrogels based on peptides and proteins. By examining patent data, researchers can identify white spaces and gain inspiration for novel solutions that address evolving hydrogel challenges. In this study, a patent analysis has been carried out to highlight the distribution of patent filings and technologies involved hydrogels. A comparison of data between peptide and protein hydrogels was then realized. With 2,608 peptide hydrogel patents, this field shows rapid growth in bioengineering and regenerative medicine, with significant international interest through the PCT system. Protein hydrogels, totaling 2,326 patents, focus on traditional biomedical applications, mainly in the US. The data reveals a higher diversity in patent types and classifications for hydrogels, underscoring their dynamic and innovative trajectory in hydrogel technology.

Protein structures frequently contain repetitive peptidic motifs that are known to be associated with important physical or biological functions. One appealing synthetic strategy for producing repetitive peptidic motifs is to oligomerize chemoselectively unprotected bifunctional peptidic monomers in water. Unfortunately, this approach is confronted with the competitive irreversible cyclization of the bifunctional monomer, resulting in dramatically low degrees of polymerization.

We undertook the challenge of addressing this issue by utilizing the native chemical ligation (NCL), chosen for its mild reaction conditions, ease of implementation, and ongoing dynamic development. As expected, the use of a bifunctional peptide monomer equipped with an N-terminal cysteine (Cys) residue and a C-terminal thioester group failed to produce the target oligomer due to the massive cyclization of the monomer. In contrast, appending a selenoethyl arm to the a-amino group of Cys led to monomer oligomerization, producing native peptide junctions to cysteine (Figure A). Key to this finding is the reversibility of monomer cyclization, which is no longer a dead end as for classical NCL with Cys residue (Figure B). Another important feature of N-selenoethyl cysteine (SetCys) is the spontaneous loss of its selenoethyl arm to produce a native Cys residue in situ (Figure C).