Group Of Peptides Research Articles

Understanding the Dynamics of Human Defensin Antimicrobial Peptides: Pathogen Resistance and Commensal Induction.

Antimicrobial peptides (AMPs), also known as host defense peptides, are petite molecules with inherent microbicidal properties that are synthesized by the host's innate immune response. These peptides serve as an initial barrier against pathogenic microorganisms, effectively eliminating them. Human defensin (HD) AMPs represent a prominent group of peptides involved in the innate immune response of humans. These peptides are primarily produced by neutrophils and epithelial cells, serving as a crucial defense mechanism against invading pathogens. The extensive research conducted has focused on the broad spectrum of antimicrobial activities and multifaceted immunomodulatory functions exhibited by human defensin AMPs. During the process of co-evolution between hosts and bacterial pathogens, bacteria have developed the ability to recognize and develop an adaptive response to AMPs to counterattack their bactericidal activity by different antibiotic-resistant mechanisms. However, numerous non-pathogenic commensal bacteria elicit the upregulation of defensins as a means to surmount the resistance mechanisms implemented by pathogens. The precise mechanism underlying the induction of HD by commensal organisms remains to be fully understood. This review summarizes the most recent research on the expression of human defensin by pathogens and discusses the various defense mechanisms used by pathogens to counter host AMP production. We also mention recent developments in the commensal induction of defensin AMPs. A better knowledge of the pathogens' defensin AMP resistance mechanisms and commensals' induction of AMP expression may shed light on the creation of fresh antibacterial tactics to get rid of bacterial infection.

Solution-Phase Late-Stage Chemoselective Photocatalytic Removal of Sulfonyl and Phenacyl Groups in Peptides.

Herein, BPC catalyzed visible-light-triggered target-specific late-stage solution phase desulfonylation from tryptophan in oligopeptides is portrayed by overcoming the isolation issue up to octamers. This robust and mild method is highly predictable and chemoselective, tolerating myriad of functional groups in aza-heteroaromatics and peptides. Interestingly, reductive desulfonylation is also amenable to biologically significant reactive histidine and tyrosine side chains, signifying the versatility of the strategy. Additional efficacy of BPC is demonstrated by solution phase phenacyl deprotection from C-terminal in peptides. Furthermore, excellent catalyst loading of 0.5 mol% and recyclability demonstrate the practical utility and applicability of this strategy.

Multidimensional vibrational circular dichroism for insect wings: Comparison of species.

This study reports the microscopic measurements of vibrational circular dichroism (VCD) on four different insect wings using a quantum cascade laser VCD system equipped with microscopic scanning capabilities (named multi-dimensional VCD [MultiD-VCD]). Wing samples, including (i) beetle, Anomala albopilosa (female), (ii) European hornet, Verspa crabro flavofasciata Cameron, 1903 (female), (iii) tiny dragonfly, Nannophya pygmae Rambur, 1842 (male), and (iv) dragonfly, Symetrum gracile Oguma, 1915 (male), were used in this study. Two-dimensional patterns of VCD signals (~10 mm × 10mm) were obtained at a spatial resolution of 100 μm. Measurements covered the absorption peaks assigned to amides I and II in the range of 1500-1740 cm-1 . The measurements were based on the enhancement of VCD signals for the stereoregular linkage of peptide groups. The patterns were remarkably dependent on the species. In samples (i) and (ii), the wings comprised segregated domains of protein aggregates of different secondary structures. The size of each microdomain was approximately 100 μm. In contrast, no clear VCD spectra were detected in samples (iii) and (iv). One possible reason was that the chain of stereoregular polypeptides was too short to achieve VCD enhancement in samples (iii) and (iv). Notably, the unique features were only observed in the VCD spectra because the IR spectra were nearly the same among the species. The VCD results hinted at the connection of protein microscopic structures with the wing flapping mechanisms of each species.

Molecular Identification and Characterization of Hevein Antimicrobial Peptide Genes in Two-Row and Six-Row Cultivars of Barley (Hordeum vulgare L.).

Heveins are one of the most important groups of plant antimicrobial peptides. So far, various roles in plant growth and development and in response to biotic and abiotic stresses have reported for heveins. The present study aimed to identify and characterize the hevein genes in two-row and six-row cultivars of barley. In total, thirteen hevein genes were identified in the genome of two-row and six-row cultivars of barley. The identified heveins were identical in two-row and six-row cultivars of barley and showed a high similarity with heveins from other plant species. The hevein coding sequences produced open reading frames (ORFs) ranged from 342 to 1002bp. Most of the identified hevein genes were intronless, and the others had only one intron. The hevein ORFs produced proteins ranged from 113 to 333 amino acids. Search for conserved functional domains showed CBD and LYZ domains in barley heveins. All barley heveins comprised extracellular signal peptides ranged from 19 to 35 amino acids. The phylogenetic analysis divided barley heveins into two groups. The promoter analysis showed regulatory elements with different frequencies between two-row and six-row cultivars. These cis-acting elements included elements related to growth and development, hormone response, and environmental stresses. The expression analysis showed high expression level of heveins in root and reproductive organs of both two-row and six-row cultivars. The expression analysis also showed that barley heveins is induced by both biotic and abiotic stresses. The results of antimicrobial activity prediction showed the highest antimicrobial activity in CBD domain of barley heveins. The findings of the current study can improve our knowledge about the role of hevein genes in plant and can be used for future studies.

Towards bone regeneration: Understanding the nucleating ability of proline-rich peptides in biomineralisation

Obtaining rapid mineralisation is a challenge in current bone graft materials, which has been attributed to the difficulty of guiding the biological processes towards osteogenesis. Amelogenin, a key protein in enamel formation, inspired the design of two intrinsically disordered peptides (P2 and P6) that enhance in vivo bone formation, but the process is not fully understood. In this study, we have elucidated the mechanism by which these peptides induce improved mineralisation. Our molecular dynamics analysis demonstrated that in an aqueous environment, P2 and P6 fold to interact with the surrounding Ca2+, PO43− and OH− ions, which can lead to apatite nucleation. Although P2 has a less stable backbone, it folds to a stable structure that allows for the nucleation of larger calcium phosphate aggregates than P6. These results were validated experimentally in a concentrated simulated body fluid solution, where the peptide solutions accelerated the mineralisation process compared to the control and yielded mineral structures mimicking the amorphous calcium phosphate crystals that can be found in lamella bone. A pH drop for the peptide groups suggests depletion of calcium and phosphate, a prerequisite for intrinsic osteoinduction, while S/TEM and SEM suggested that the peptide regulated the mineral nucleation into lamella flakes. Evidently, the peptides accelerate and guide mineral formation, elucidating the mechanism for how these peptides can improve the efficacy of P2 or P6 containing devices for bone regeneration. The work also demonstrates how experimental mineralisation study coupled with molecular dynamics is a valid method for understanding and predicting in vivo performance prior to animal trials.

An efficient consolidation of word embedding and deep learning techniques for classifying anticancer peptides: FastText+BiLSTM.

Anticancer peptides (ACPs) are a group of peptides that exhibit antineoplastic properties. The utilization of ACPs in cancer prevention can present a viable substitute for conventional cancer therapeutics, as they possess a higher degree of selectivity and safety. Recent scientific advancements generate an interest in peptide-based therapies which offer the advantage of efficiently treating intended cells without negatively impacting normal cells. However, as the number of peptide sequences continues to increase rapidly, developing a reliable and precise prediction model becomes a challenging task. In this work, our motivation is to advance an efficient model for categorizing anticancer peptides employing the consolidation of word embedding and deep learning models. First, Word2Vec, GloVe, FastText, One-Hot-Encoding approaches are evaluated as embedding techniques for the purpose of extracting peptide sequences. Then, the output of embedding models are fed into deep learning approaches CNN, LSTM, BiLSTM. To demonstrate the contribution of proposed framework, extensive experiments are carried on widely-used datasets in the literature, ACPs250 and independent. Experiment results show the usage of proposed model enhances classification accuracy when compared to the state-of-the-art studies. The proposed combination, FastText+BiLSTM, exhibits 92.50% of accuracy for ACPs250 dataset, and 96.15% of accuracy for the Independent dataset, thence determining new state-of-the-art.

Identification of Binding Sites in Copper(II)-Peptide Complexes Using Infrared Spectroscopy.

Complex formation of the copper(II) ion (CuII) with histidine (H) and H-containing peptides plays a crucial role in various metallo-enzymatic reactions. To elucidate the nature of coordinate bonding in CuII complexes, Fourier-transform infrared spectroscopy and 2D IR spectroscopy were employed to investigate the coordination geometries of CuII with diglycine, l-histidylglycine (HG), glycyl-l-histidine (GH), and glycylglycyl-l-histidine. The coordination of CuII to different peptide groups, including the peptide N- and C-termini, the amide group, and the imidazole of the H side chain, exhibits distinct spectral features. The derived molecular structure of the CuII-HG complex based on these spectral features significantly differs from that of CuII-GH, suggesting a preference of the N-terminus and the steric hindrance of the H side chain in CuII chelation.

Engineering circular bacteriocins: structural and functional effects of α-helix exchanges and disulfide introductions in circularin A.

Circular bacteriocins form a distinct group of antimicrobial peptides (AMPs) characterized by their unique head-to-tail ligated circular structure and functional properties. They belong to the ribosomally synthesized and post-translationally modified peptide (RiPP) family. The ribosomal origin of these peptides facilitates rapid diversification through mutations in the precursor genes combined with specific modification enzymes. In this study, we primarily explored the bacteriocin engineering potential of circularin A, a circular bacteriocin produced by Clostridium beijerinckii ATCC 25752. Specifically, we employed strategies involving α-helix replacements and disulfide bond introductions to investigate their effects on both biosynthesis and bioactivity of the bacteriocin. The results show the feasibility of peptide engineering to introduce certain structural properties into circularin A through carefully designed approaches. The introduction of cysteines for potential disulfide bonds resulted in a substantial reduction in bacteriocin biosynthesis and/or bioactivity, indicating the importance of maintaining dynamic flexibility of α-helices in circularin A, while reduction of the potential disulfide in one case increased the activity. The 5 α-helices of circularin A were respectively replaced by corresponding helices from another circular peptide, enterocin AS-48, and modestly active peptides were obtained in a few cases. Overall, this study provides valuable insights into the engineering potential of circular bacteriocins as antimicrobial agents, including their structural and functional restrictions and their suitability as peptide engineering scaffolds. This helps to pave the way for the development of novel antimicrobial peptides with tailored properties based on circular bacteriocins.

Discovery and characterization of anti-cancer peptides from a random peptide library.

We performed a forward genetic screen to discover peptides that specifically target breast cancer cells using a Penetratin tagged, random 15mer peptide library. We identified a group of novel peptides that specifically inhibited the proliferation and survival of breast cancer cells without affecting normal primary mammary epithelial cells or fibroblasts. The intrinsic apoptotic pathway is activated by these peptides in the face of abnormal expression of numerous cell cycle regulatory genes. Associated alterations in histone marks, nuclear structure, and levels of critical RNA binding proteins vary in a peptide specific manner. This study demonstrates a novel method for the discovery of new potential therapeutic peptides.

Utilization POME as growth substrate for local indigenous bacteria Bacillus sp. ALP D1 in producing biosurfactant

Palm Oil Mill Effluent (POME) is a liquid palm oil waste that has beneficial value because of the nutritional content it contains. This research aim to obtain biosurfactant by using POME as a growth substrate. The methods used include biosurfactant production, extraction using acid precipitation, and characterization using TLC, FTIR, and LC-MS. The results showed that the local indigenous bacteria Bacillus sp. ALP D1 can produce biosurfactant under conditions of growth of POME 3%, NaNO3 3%, pH 6, salinity 7% with an IE24 of 69.44%, diameter of oil spreading test at 8.5 cm, and positive at drop collapse test. The extraction stage produces a brownish-yellow crude extract of 0.068 g/L. Biosurfactant characterization using TLC showed pink spots with ninhydrin reagent indicating the presence of nitrogen groups from peptide in the biosurfactant. This is supported by the results of FTIR analysis with the presence of an N-H peak from the peptide group in the absorption area 3384 cm-1. The results of the LC-MS analysis showed that the biosurfactant obtained had Rt 14.64 minutes and 332.22 m/z. Based on the results, it is suspected that the biosurfactant produced by Bacillus sp. ALP D1 is a lipopeptide.

Facile synthesis of peptides anchored g-C3N4 nanosheets for efficient photocatalytic hydrogen generation

This work demonstrated the synthesis of peptides decorated porous g-C3N4 hybrids (R-CN) for the enhanced photocatalytic H2 production, where the 14-mer peptides were effectively deposited on g-C3N4 nanosheets by electrostatic interaction. The prepared R-CN hybrid composite shows the enhanced visible light absorption due to the modulation of electronic structures of g-C3N4 by the interaction between peptides and g-C3N4. Therefore, the R-CN hybrid composite demonstrated the excellent photocatalytic H2 production with yield of 2018 μmol·g−1·h−1 under the visible light irradiation, which is 14-time higher than that of pristine g-C3N4. The theoretical study shows that the strained heptazine planes in the g-C3N4 structure is formed in the R-CN hybrid composites by the electrostatic interaction between the positively charged amine group of peptides and the negatively charged edge N atom of g-C3N4. Thus, the electron redistribution and delocalization in the R-CN composite lead the band gap reduction, build-in electrical field and electronic modulation. Therefore, the R-CN composites shows the enhanced charge separation and the optimized free energy of reaction intermediates for the excellent photocatalytic activities. These results are confirmed from the experimental measurements and the MD and DFT computations study. This work provides an effective strategy to design biomaterial-based metal-free photocatalysts for H2 production.

The Role of Adipokines in the Control of Pituitary Functions.

The pituitary gland is a key endocrine gland in all classes of vertebrates, including mammals. The pituitary gland is an important component of hypothalamus-pituitary-target organ hormonal regulatory axes and forms a functional link between the nervous system and the endocrine system. In response to hypothalamic stimuli, the pituitary gland secretes a number of hormones involved in the regulation of metabolism, stress reactions and environmental adaptation, growth and development, as well as reproductive processes and lactation. In turn, hormones secreted by target organs at the lowest levels of the hormonal regulatory axes regulate the functions of the pituitary gland in the process of hormonal feedback. The pituitary also responds to other peripheral signals, including adipose-tissue-derived factors. These substances are a broad group of peptides known as adipocytokines or adipokines that act as endocrine hormones mainly involved in energy homeostasis. Adipokines, including adiponectin, resistin, apelin, chemerin, visfatin, and irisin, are also expressed in the pituitary gland, and they influence the secretory functions of this gland. This review is an overview of the existing knowledge of the relationship between chosen adipose-derived factors and endocrine functions of the pituitary gland, with an emphasis on the pituitary control of reproductive processes.

Comparison of the structure-function of five newly members of the calcin family

Calcins are a group of scorpion toxin peptides specifically binding to ryanodine receptors (RyRs) with high affinity, and have the ability to activate and stabilize RyR in a long-lasting subconductance state. Five newly calcins synthesized compounds exhibit typical structural characteristics of a specific family through chemical synthesis and virtual analysis. As the calcins from the same species, Petersiicalcin1 and Petersiicalcin2, Jendekicalcin2 and Jendekicalcin3, have only one residue difference. Both Petersiicalcin1 and Petersiicalcin2 exhibited different affinities in stimulating [3H]ryanodine binding, but the residue mutation resulted in a 2.7 folds difference. Other calcins also exhibited a stimulatory effect on [3H]ryanodine binding to RyR1, however, their affinities were significantly lower than that of Petersiiicalcin1 and Petersiiicalcin2. The channel domain of RyR1 was found to be capable of binding with the basic residues of these calcins, which also exhibited interactions with the S6 helices on RyR1. Dynamic simulations were conducted for Petersiicalcin1 and Petersiicalcin2, which demonstrated their ability to form a highly stable conformation and resulting in an asymmetric tetramer structure of RyR1. The discovery of five newly calcins further enriches the diversity of the natural calcin family, which provides more native peptides for the structure-function analysis between calcin and RyRs.

Altering Specificity and Enhancing Stability of the Antimicrobial Peptides Nisin and Rombocin through Dehydrated Amino Acid Residue Engineering

Nisin serves as the prototype within the lantibiotic group of antimicrobial peptides, exhibiting a broad-spectrum inhibition against Gram-positive bacteria, including important food-borne pathogens and clinically relevant antibiotic-resistant strains. The gene-encoded nature of nisin allows for gene-based bioengineering, enabling the generation of novel derivatives. It has been demonstrated that nisin mutants can be produced with improved functional properties. Here, we particularly focus on the uncommon amino acid residues dehydroalanine (Dha) and dehydrobutyrin (Dhb), whose functions are not yet fully elucidated. Prior to this study, we developed a new expression system that utilizes the nisin modification machinery NisBTC to advance expression, resulting in enhanced peptide dehydration efficiency. Through this approach, we discovered that the dehydrated amino acid Dhb at position 18 in the peptide rombocin, a short variant of nisin, displayed four times higher activity compared to the non-dehydrated peptide against the strain Lactococcus lactis. Furthermore, we observed that in the peptides nisin and rombocin, the dehydrated amino acid Dha at residue positon 18 exhibited superior activity compared to the dehydrated amino acid Dhb. Upon purifying the wild-type nisin and its variant nisinG18/Dha to homogeneity, the minimum inhibitory concentration (MIC) indicated that the variant exhibited activity similar to that of wild-type nisin in inhibiting the growth of Bacillus cereus but showed twice the MIC values against the other four tested Gram-positive strains. Further stability tests demonstrated that the dehydrated peptide exhibited properties similar to wild-type nisin under different temperatures but displayed higher resistance to proteolytic enzymes compared to wild-type nisin.

Development and validation of cyclic peptide probe for gastric cancer based on phage display technique

AbstractCancer‐targeting diagnostics should have a sensitive and specific binding affinity. To achieve this, biomarker development is critical. This study aimed to develop and validate a 7‐mer cyclic peptide probe that can target gastric cancer. We developed this probe based on LGR5 (leucine‐rich repeat‐containing G‐protein coupled receptor 5)‐specific targeting, which is a marker for gastric cancer stem cells. An LGR5 targeting peptide sequence that was developed using phage display technology resulted in a cyclic peptide, C‐YLASRVH‐C (named YLA). We conjugated this peptide with fluorescent probes to validate its specific targeting ability for gastric cancer. The fluorescence‐labeled YLA peptide exhibited 3.0‐fold higher fluorescence intensity in a gastric cancer cell line (MKN45) than it did in a normal cell line (CCD841 cells). In contrast, pancreatic and colorectal cancer cells did not show significant fluorescence intensity with the YLA peptide. To verify its tumor‐targeting affinity, we developed a control peptide, C‐YLASAVH‐C (named YLASA) using an ALA scanning experiment. Whole‐body imaging of a gastric cancer xenograft model showed higher fluorescence intensity of tumors in the YLA peptide group than in the control peptide group. Moreover, ex vivo imaging of tumor tissues exhibited 6.8‐fold higher fluorescence intensity in the YLA peptide group compared to that in the YLASA control peptide group. In conclusion, we confirmed that the YLA peptide probe functions as a specific diagnostic probe for gastric cancer. We anticipate that it will play a theranostic role through further development.

Efficient biosynthesis of transglutaminase in Streptomyces mobaraensis via systematic engineering strategies

Transglutaminases (TGases) have been widely used in food, pharmaceutical, biotechnology, and other industries because of their ability to catalyze deamidation, acyl transfer, and crosslinking reactions between Ƴ-carboxamide groups of peptides or protein-bound glutamine and the Ɛ-amino group of lysine. In this study, we demonstrated an efficient systematic engineering strategy to enhance the synthesis of TGase in a recombinant Streptomyces mobaraensis smL2020 strain in a 1000-L fermentor. Briefly, the enzymatic properties of the TGase TGL2020 from S. mobaraensis smL2020 and TGase TGLD from S. mobaraensis smLD were compared to obtain the TGase TGLD with perfected characteristics for heterologous expression in a recombinant S. mobaraensis smL2020ΔTG without the gene tgL 2020. Through multiple engineering strategies, including promoter engineering, optimizing the signal peptides and recombination sites, and increasing copies of the expression cassettes, the final TGLD activity in the recombinant S. mobaraensis smL2020ΔTG: (PL2020-spL2020-protgLD-tgLD)2 (tgL2020and BT1) reached 56.43 U/mL and 63.18 U/mL in shake flask and 1000-L fermentor, respectively, which was the highest reported to date. With the improvement of expression level, the application scope of TGLD in the food industry will continue to expand. Moreover, the genetic stability of the recombinant strain maintained at more than 20 generations. These findings proved the feasibility of multiple systematic engineering strategies in synthetic biology and provided an emerging solution to improve biosynthesis of industrial enzymes.

Влияние дулаглутида на метаболическую адаптацию у больных сахарным диабетом 2 типа и ожирением

Aim. To evaluate the effect of dulaglutide, a glucose-lowering drug from the group of glucagon-like peptide 1 receptor (GLP-1) agonists, on indicators of fat metabolism and irisin. Design. Open pilot study. Materials and methods. 85 people (56 women, 29 men) with type 2 diabetes mellitus and obesity of varying severity took part in the study. 17 of them had a history of myocardial infarction, 2 patients had stroke (acute cerebrovascular accident), and all the rest had arterial hypertension. All patients were prescribed dulaglutide, a GLP-1 agonist, for ongoing glucose-lowering therapy for the purpose of intensification. Results. After 12 months of therapy, a statistically significant (р < 0.05) decrease in anthropometric parameters was obtained: body weight decreased from 110 (70–185) to 105.5 (60–159) kg, waist circumference decreased from 124.5 (46.4–150) to 119 (90–146) cm. The levels of glycated hemoglobin statistically significantly decreased — from 7.1% (5.4–10.6%) to 6.5% (6.2–12.4%) (р < 0.05), total cholesterol — from 4.89 (2.07–15) to 4.55 (2.19–8.33) mmol/l (р < 0.05), leptin — from 32.9 (14.9–127.6) to 24.5 (13.5–133.7) ng/ml (р < 0.05), C-reactive protein — from 3.37 (0.01–64.2) to 2.24 (0.01–54.1) mg/ml (р < 0.05), the HOMA β level statistically significantly increased — from 80 (4–359) to 110 (12.2–755) (р < 0.05). In addition, the thickness of epicardial fat according to echocardiography significantly decreased — from 11 (2.5–20) to 10 (7–15) mm (р < 0.05), as well as the amount of adipose tissue according to bioimpedance measurements from 52.3 (26.6–99.8) to 44.7 (28.2–73.9) kg (р < 0.05). Conclusion. In patients with type 2 diabetes and obesity, therapy with GLP-1 agonist dulaglutide after 12 months contributed to a significant improvement in glycemic control and pancreatic β-cell function. In patients with type 2 diabetes and obesity, therapy with GLP-1 agonist the dulaglutide after 12 months, a significant decrease in body weight, the amount of adipose tissue, and epicardial fat was observed. Regression of adipose tissue according to bioimpedansometry data was accompanied by a significant decrease in the level of leptin, a marker of inflammation C-reactive protein, and a tendency to increase the level of adiponectin and irisin. Keywords: dulaglutide, obesity, type 2 diabetes mellitus, irisin, fat metabolism.

Diagnostic and predictive abilities of myokines in patients with heart failure.

Myokines are defined as a heterogenic group of numerous cytokines, peptides and metabolic derivates, which are expressed, synthesized, produced, and released by skeletal myocytes and myocardial cells and exert either auto- and paracrine, or endocrine effects. Previous studies revealed that myokines play a pivotal role in mutual communications between skeletal muscles, myocardium and remote organs, such as brain, vasculature, bone, liver, pancreas, white adipose tissue, gut, and skin. Despite several myokines exert complete divorced biological effects mainly in regulation of skeletal muscle hypertrophy, residential cells differentiation, neovascularization/angiogenesis, vascular integrity, endothelial function, inflammation and apoptosis/necrosis, attenuating ischemia/hypoxia and tissue protection, tumor growth and malignance, for other occasions, their predominant effects affect energy homeostasis, glucose and lipid metabolism, adiposity, muscle training adaptation and food behavior. Last decade had been identified 250 more myokines, which have been investigating for many years further as either biomarkers or targets for heart failure management. However, only few myokines have been allocated to a promising tool for monitoring adverse cardiac remodeling, ischemia/hypoxia-related target-organ dysfunction, microvascular inflammation, sarcopenia/myopathy and prediction for poor clinical outcomes among patients with HF. This we concentrate on some most plausible myokines, such as myostatin, myonectin, brain-derived neurotrophic factor, muslin, fibroblast growth factor 21, irisin, leukemia inhibitory factor, developmental endothelial locus-1, interleukin-6, nerve growth factor and insulin-like growth factor-1, which are suggested to be useful biomarkers for HF development and progression.

Specific interaction between the DSPHTELP peptide and various functional groups.

M13 bacteriophages serve as a versatile foundation for nanobiotechnology due to their unique biological and chemical properties. The polypeptides that comprise their coat proteins, specifically pVIII, can be precisely tailored through genetic engineering. This enables the customized integration of various functional elements through specific interactions, leading to the development of innovative hybrid materials for applications such as energy storage, biosensing, and catalysis. Notably, a certain genetically engineered M13 bacteriophage variant, referred to as DSPH, features a pVIII with a repeating DSPHTELP peptide sequence. This sequence facilitates specific adhesion to single-walled carbon nanotubes (SWCNTs), primarily through π-π and hydrophobic interactions, though the exact mechanism remains unconfirmed. In this study, we synthesized the DSPHTELP peptide (an 8-mer peptide) and analyzed its interaction forces with different functional groups across various pH levels using surface forces apparatus (SFA). Our findings indicate that the 8-mer peptide binds most strongly to CH3 groups (Wad = 13.74 ± 1.04 mJ m-2 at pH 3.0), suggesting that hydrophobic interactions are indeed the predominant mechanism. These insights offer both quantitative and qualitative understanding of the molecular interaction mechanisms of the 8-mer peptide and clarify the basis of its specific interaction with SWCNTs through the DSPHTELP M13 bacteriophage.

Study on the mechanism of mitigating radiation damage by improving the hematopoietic system and intestinal barrier with Tenebrio molitor peptides.

Research on plant and animal peptides has garnered significant attention, but there is a lack of studies on the functional properties of Tenebrio molitor peptides, particularly in relation to their potential mitigating effect on radiation damage and the underlying mechanisms. This study aims to explore the protective effects of Tenebrio molitor peptides against radiation-induced damage. Mice were divided into five groups: normal, radiation model, and low-, medium-, and high-dose Tenebrio molitor peptide (TMP) groups (0.15 g per kg BW, 0.30 g per kg BW, and 0.60 g per kg BW). Various parameters such as blood cell counts, bone marrow DNA content, immune organ indices, serum levels of D-lactic acid, diamine oxidase (DAO), endotoxin (LPS), and inflammatory factors were assessed at 3 and 15 days post gamma irradiation. Additionally, the intestinal tissue morphology was examined through H&E staining, RT-qPCR experiments were conducted to analyze the expression of inflammatory factors in the intestine, and immunohistochemistry was utilized to evaluate the expression of tight junction proteins ZO-1 and Occludin in the intestine. The findings revealed that high-dose TMP significantly enhanced the hematopoietic system function in mice post radiation exposure, leading to increased spleen index, thymus index, blood cell counts, and bone marrow DNA production (p < 0.05). Moreover, TMP improved the intestinal barrier integrity and reduced the intestinal permeability. Mechanistic insights suggested that these peptides may safeguard intestinal barrier function by downregulating the gene expression of inflammatory factors TNF-α, IL-1β, and IL-6, while upregulating the expression of tight junction proteins ZO-1 and Occludin (p < 0.05). Overall, supplementation with TMP mitigates radiation-induced intestinal damage by enhancing the hematopoietic system and the intestinal barrier, offering valuable insights for further investigations into the mechanisms underlying the protective effects of these peptides against ionizing radiation.