Peptide Bond Research Articles

A Numerical Integrator for Kinetostatic Folding of Protein Molecules Modeled as Robots with Hyper Degrees of Freedom

The kinetostatic compliance method (KCM) models protein molecules as nanomechanisms consisting of numerous rigid peptide plane linkages. These linkages articulate with respect to each other through changes in the molecule dihedral angles, resulting in a kinematic mechanism with hyper degrees of freedom. Within the KCM framework, nonlinear interatomic forces drive protein folding by guiding the molecule’s dihedral angle vector towards its lowest energy state in a kinetostatic manner. This paper proposes a numerical integrator that is well suited to KCM-based protein folding and overcomes the limitations of traditional explicit Euler methods with fixed step size. Our proposed integration scheme is based on pseudo-transient continuation with an adaptive step size updating rule that can efficiently compute protein folding pathways, namely, the transient three-dimensional configurations of protein molecules during folding. Numerical simulations utilizing the KCM approach on protein backbones confirm the effectiveness of the proposed integrator.

Indium‐Catalyzed Direct Amidation Reaction of Carboxylic Acids and In Silico Study for Screening the Activity of Potential Therapeutics of the Synthesized Products

AbstractAmide bonds are ubiquitous and valuable motifs in synthetic chemistry, found in a wide range of applications such as the backbone of proteins and pharmaceutical agents. Thus, environmentally friendly and selective methods for synthesizing amide bonds are important. Herein, we report a simple, efficient, and rapid route to access a range of functionalized amides from non‐activated carboxylic acids and amines using indium (III) trifluoromethanesulfonate as an efficient catalyst. A wide range of carboxylic acids – including aliphatic, aromatic, heterocyclic, and dicarbonyl acids – participate smoothly in these reactions, generating structurally diverse amides in moderate to good yields (up to 91 % in 24 examples). The reactions are conducted in dry tetrahydrofuran (THF) under reflux conditions. Furthermore, this amidation strategy provides a method for addressing challenging molecules, such as protected amino acids, to produce biocompatible products. These products can then be used as substrates for various organic transformations, including C−H functionalization reactions. We also demonstrate the synthetic utility of our protocol through the synthesis of essential substrates in organic and medicinal chemistry by reacting N‐protected carboxylic acids with 8‐aminoquinoline to produce a series of biologically valuable compounds. Five of these products, named 4 f, 4p, 9a, 9c, and 9d, have been biologically evaluated through an in‐silico study. The interaction of these compounds with receptor protein 8DQT was examined to assess their potential as drug candidates for hypertension treatment. Effective binding was detected between these compounds and the receptor. Data from molecular docking studies show that compounds 4d and 4 m are the most active, with binding scores of −8.8 and −8.6 kcal/mol, respectively. However, compound 4 m exhibited a stronger binding affinity than compound 4d over the course of dynamic simulation. Our ADMET study suggests that all five compounds are highly safe in the body. Based on the BOILED‐Egg model study, good absorption is suggested for all the molecules, and they can cross the blood‐brain barrier.

CAPE derivatives: Multifaceted agents for chronic wound healing.

Chronic wounds significantly impact the patients' quality of life, creating an urgent interdisciplinary clinical challenge. The development of novel agents capable of accelerating the healing process is essential. Caffeic acid phenethyl ester (CAPE) has demonstrated positive effects on skin regeneration. However, its susceptibility to degradation limits its pharmaceutical application. Chemical modification of the structure improves the pharmacokinetics of this bioactive phenol. Hence, two novel series of CAPE hybrids were designed, synthesized, and investigated as potential skin regenerative agents. To enhance the stability and therapeutic efficacy, a caffeic acid frame was combined with quinolines or isoquinolines by an ester (1a-f) or an amide linkage (2a-f). The effects on cell viability of human gingival fibroblasts (HGFs) and HaCaT cells were evaluated at different concentrations; they are not cytotoxic, and some proved to stimulate cell proliferation. The most promising compounds underwent a wound-healing assay in HGFs and HaCaT at the lowest concentrations. Antimicrobial antioxidant properties were also explored. The chemical and thermal stabilities of the best compounds were assessed. In silico predictions were employed to anticipate skin penetration capabilities. Our findings highlight the therapeutic potential of caffeic acid phenethyl ester (CAPE) derivatives 1a and 1d as skin regenerative agents, being able to stimulate cell proliferation, control bacterial growth, regulate ROS levels, and being thermally and chemically stable. An interesting structure-activity relationship was discussed to suggest a promising multitargeted approach for enhanced wound healing.

Effect of low degree succinylation on properties of enzyme-induced casein hydrogel

This study examines the impact of succinic anhydride (SA) modification (0–9 %) on the gel properties of casein. Upon succinylation, the surface hydrophobicity (H0) of casein initially increased before decreasing, achieving its peak at a degree of succinylation of 5.22 ± 0.16 %. The α-helix content rose to 14.13 ± 2.60 %, and the -OH peak shifted towards lower wavenumbers, suggesting enhanced hydrogen bonding within intra/intermolecular structures. The storage modulus in the rheological test escalated from 2160.11 Pa to 5047.60 Pa, and SEM analysis revealed that the optimally succinylated casein gel formed a denser and more stable gel network structure. Moreover, succinylated casein hydrogels demonstrated superior texture properties, swelling ability, and thermal stability. Molecular dynamics simulation (MD) results suggest that SA preferentially binds to LYS27 and LYS28 of β-casein via hydrogen bonds and amide bonds, respectively. The interaction between modified proteins is primarily governed by hydrogen bonds, aligning with FT-IR findings. PCA analysis identified a positive correlation between the ordered structure and gel performance. This research offers theoretical insights and reference data for modulating casein hydrogel properties through succinylation.

An experimental and computational investigation of the cyclopentene-containing peptide-derived compounds: focus on pseudo-cyclic motifs via intramolecular interactions.

Conformational flexibility is one of the main disadvantages of peptide-based compounds. We focus on their molecular 'chameleonicity' related to forming pseudo-cyclic motifs via modulation of weak intramolecular interactions. It is an appealing strategy for controlling equilibrium between the polar open and the nonpolar closed conformations. Within this context, we report here the crystal structure of the (R)-(2-tert-butoxycarbonyl)amino-1-oxo-3-phenyl)propyl)-1-cyclopentene (1), synthesis of which in high yield was achieved by a facile multi-step protocol. Our Cambridge Structural Database (CSD) overview for the peptide-based crystals revealed the exclusivity of this compound from the viewpoint of the unusual pseudo-bicyclic system via C-H…O and C-O…π interactions, in which cyclopentene shields the amide bond. Notably, cyclopentene as a bioisostere of proline is an appealing scaffold in medicinal chemistry. An extensive combined experimental and computational study provided more profound insight into the supramolecular landscape of 1 with respect to similar derivatives deposited in the CSD, including the tendency of cyclopentene for the generation of pseudo-cyclic motifs through weak H-bonding and π-based intramolecular interactions. These weak interactions have been examined by either the quantum theory of 'atoms-in-molecules' (QTAIM) or complex Hirshfeld surface methodology, including enrichment ratios, molecular electrostatic potential surfaces and energy frameworks. In all analysed crystals, all types of H-bonded motifs involving cyclopentene are formed at all levels of supramolecular architecture. A library of cyclopentene-based H-bonding synthons is provided. A molecular docking study depicted vital interactions of cyclopentene with key amino acid residues inside the active sites of two prominent protein kinases, uncovering the therapeutic potential of 1 against breast cancer. To a large extent, dispersion forces have significance in stabilizing the supramolecular structure of both ligand and bio-complex ligand-protein. Finally, the satisfactory in silico bio-pharmacokinetic profile of 1 related to drug-likeness and blood-brain barrier permeation was also revealed.

Investigation of Photoinduced Deterioration in Shadow Puppet Artifacts Collected from the National Shadow Pupperty Museum in Chengdu, China

Shadow puppet artifacts are a special type of cultural heritage made from animal skin, possessing significant cultural and artistic value. However, there is insufficient attention to the scientific preservation of these artifacts, and systematic research on their protection is lacking. In particular, light as an important factor and related conservation studies are weak. This study investigates the photoinduced deterioration of shadow puppet artifacts from the National Shadow Pupperty Museum in Chengdu collection. Based on the xenon arc lamp are a common method of light aging, the modern rawhide samples were aged by the xenon arc lamp to simulate photoinduced deterioration. After artificial light aging, the samples were stored in a stable environment (with temperature maintained at 22 ± 2°C and relative humidity maintained at 50 ± 5%RH) for 150 days. It attempts to avoid further deterioration of the samples due to drastic cyclic changes in the environment. And continuously observe changes in characteristics during this process to verify the potential reversibility of photoinduced deterioration. Comprehensive assessments were conducted to gauge the extent of deterioration. In order to assess the deterioration, a series of analytical techniques were used. Moisture gain or loss was inferred from mass changes, and colorimetric measurements were measured using the CIELAB formula. Macroscopic and microscopic morphological damage was documented through camera, stereo microscope, and scanning electron microscope observations. Fourier transform infrared spectroscopy (FTIR) assessed amide bond degradation and moisture loss, while thermogravimetry/differential thermogravimetry (TG/DTG) evaluated collagen denaturation and thermal stability. The results indicated that prolonged light exposure caused significant deterioration, including color fading, moisture evaporation, and structural damage such as shrinkage and cracking. The findings indicate that light exposure is a crucial factor in the preservation of shadow puppet artifacts. Therefore, it is essential to implement careful management strategies in museum environments to ensure the protection of these artifacts.

ROS-mediated damage to the core domain of HIV integrase: A molecular dynamics simulation

Using molecular dynamics simulation with reactive force-field (ReaxFF), we study the reactive oxygen species (ROS)-mediated damage to the core domain of human immunodeficiency virus (HIV) integrase. Our results demonstrate that with the increase in the ROS concentration, the structure of the core domain of HIV is more severely damaged, including dehydrogenation, increasing oxygen-containing groups, shorting or damaging spirals, and breaking peptide bonds. We particularly note that ROS has a significantly higher capability to abstract H atoms from N atoms than C atoms. The effects of different species of ROS on dehydrogenation and shorting or damaging spirals are not prominent. In contrast, for increasing oxygen-containing groups and breaking peptide bonds, the effect of O is more remarkable than O3 and O3 is greater than ·OH. Moreover, carboxyl dehydrogenation and nitrogen dehydrogenation are more easily dehydrogenated, resulting in higher dehydrogenation ratios for polar amino acid residues. These meticulous findings deepen our understanding of the role of ROS in regulating the structure and function of the core domain of HIV integrase and provide valuable insights into the plasma treatment of acquired immune deficiency syndrome.

UCHL1 Overexpression Is Related to the Aggressive Phenotype of Non-small Cell Lung Cancer.

Ubiquitin C-terminal hydrolase L1 (UCHL1), which encodes thiol protease that hydrolyzes a peptide bond at the C-terminal glycine residue of ubiquitin, regulates cell differentiation, proliferation, transcriptional regulation, and numerous other biological processes and may be involved in lung cancer progression. UCHL1 is mainly expressed in the brain and plays a tumor-promoting role in a few cancer types; however, there are limited reports regarding its role in lung cancer. Single-cell RNA (scRNA) sequencing using 10X chromium v3 was performed on a paired normal-appearing and tumor tissue from surgical specimens of a patient who showed unusually rapid progression. To validate clinical implication of the identified biomarkers, immunohistochemical (IHC) analysis was performed on 48 non-small cell lung cancer (NSCLC) tissue specimens, and the correlation with clinical parameters was evaluated. We identified 500 genes overexpressed in tumor tissue compared to those in normal tissue. Among them, UCHL1, brain expressed X-linked 3 (BEX3), and midkine (MDK), which are associated with tumor growth and progression, exhibited a 1.5-fold increase in expression compared to that in normal tissue. IHC analysis of NSCLC tissues showed that only UCHL1 was specifically overexpressed. Additionally, in 48 NSCLC specimens, UCHL1 was specifically upregulated in the cytoplasm and nuclear membrane of tumor cells. Multivariable logistic analysis identified several factors, including smoking, tumor size, and high-grade dysplasia, to be typically associated with UCHL1 overexpression. Survival analyses using The Cancer Genome Atlas (TCGA) datasets revealed that UCHL1 overexpression is substantially associated with poor survival outcomes. Furthermore, a strong association was observed between UCHL1 expression and the clinicopathological features of patients with NSCLC. UCHL1 overexpression was associated with smoking, tumor size, and high-grade dysplasia, which are typically associated with a poor prognosis and survival outcome. These findings suggest that UCHL1 may serve as an effective biomarker of NSCLC.

Growth of dendritic CuS nanostructures for photoacoustic image guided Chemo-Photothermal therapy

Herein, we report a unique method for design and development of carboxyl enriched dendritic CuS nanostructures (CuS NSs) for photoacoustic image guided chemo-photothermal therapy. The dendritic network was grown on the surface of CuS nanoparticles via layer-by-layer assembly of amino acid. XRD and TEM studies established the formation of crystalline well-spherical nanosized hexagonal covellite (CuS) phase. The successful growth of dendritic structure was apparent from the rise in surface charge, hydrodynamic diameter and characteristic vibrational band intensity of peptide bonds. The developed different generations of dendritic CuS NSs (D0-CuS NSs, D1-CuS NSs, D2-CuS NSs and D3-CuS NSs) displayed wide-ranging absorption band in near infrared (NIR) zone and exhibited good photothermal heating efficacy upon irradiation of 980 nm laser light. From in to vitro cellular studies, it has been found that the NIR irradiation effectively enhanced the photothermal toxicity of D3-CuS NSs towards cancer cells. Moreover, these negatively charged water-dispersible D3-CuS NSs were conjugated with positively charged anticancer drug, doxorubicin hydrochloride (DOX) through electrostatic interaction. The DOX loaded D3-CuS NSs (DOX@D3-CuS NSs) revealed pH dependent drug release behaviour and their considerable uptake in breast cancer cells (MCF-7). Further, DOX@D3-CuS NSs exhibited a much higher toxicity towards cancer cells upon NIR light over individual counterparts suggesting their strong ability for chemo-photothermal therapy. Moreover, these biocompatible CuS NSs have shown excellent concentration dependent photoacoustic properties at pulse laser excitation (850 nm) and thus, they can be found potential application in chemo-photothermal therapy.

Structural Properties of Globulin: A Critical Parameter for Sunflower Meal as Wood Panel Adhesives.

Alternative biobased adhesive formulations are currently being investigated to replace urea-formaldehyde (UF) as wood panel adhesives. In this regard, oilseed meals are valuable alternatives, as it is anticipated that the sticky potential of these meals is linked to their protein content. This work focuses on the protein parameters (primary and/or secondary structures) that could impact the adhesiveness of sunflower meals. The proteins contained in these meals were first separated from the other components and identified using electrophoresis. Oilseed meals contain several families of proteins: globulins, albumins, prolamins, and oleosins. Sunflower meal is mainly composed of globulin (53%) and albumin (45%). The protein structures have then been either oxidized with H2O2 (in the presence or not of NaOH) or physically treated by microwave (MW). The oxidation treatment cleaves the protein backbone and creates smaller peptides, while the MW process converts α-helices into random coils. The adhesive potential of these treated proteins was evaluated by using shear tests onto wood panels. The results demonstrate that the primary and secondary structures of globulins are key parameters toward the sunflower protein meal adhesivity.

Rapid Interpretation of Protein Backbone Rotation Dynamics Directly from Spin Relaxation Data.

Besides their structure, dynamics is pivotal for protein functions, particularly for intrinsically disordered proteins (IDPs) that do not fold into a fixed 3D structure. However, the detection of protein dynamics is difficult for IDPs and other disordered biomolecules. NMR spin relaxation rates are sensitive to the rapid rotations of chemical bonds, but their interpretation is arduous for IDPs or molecular assemblies with a complex dynamic landscape. Here we demonstrate numerically that the dynamics of a wide range of proteins, from short peptides to partially disordered proteins and peptides in micelles, can be characterized by calculating the total effective correlation times of protein backbone N-H bond rotations, τeff, from experimentally measured transverse 15N spin relaxation rates, R2, using a linear relation. Our results enable the determination of magnetic-field-independent and intuitively understandable parameters describing protein dynamics at different regions of the sequence directly from experiments. A practical advance of the approach is demonstrated by analyzing partially disordered proteins in which rotations of disordered regions occur with timescales of 1-2 ns, independent of their size, suggesting that rotations of disordered and folded regions are uncoupled in these proteins.

Establishing a novel covalent complex of wheat gluten with tea polyphenols: Structure, digestion, and action mechanism

Plant-based proteins represent a more sustainable alternative, the approaches to modify and enhance their functionality and application are focused on. Covalent interaction could significantly modify the structure and function properties of protein. This study investigated the effects of covalent interaction between wheat gluten and tea polyphenols on the structure, aggregation, stability, and digestive properties of their covalent complex, as well as the possible action mechanism. The results showed that tea polyphenols could interact with gluten via covalent bonds (CN and/or CS), while tea polyphenols also acted as a bridge connecting gluten molecules, thus making covalent complex to show the larger particle sizes. This covalent interaction significantly changed the secondary structure, tertiary structure, and surface hydrophobicity of gluten. Moreover, covalent complex exhibited the high polyphenols bioaccessibility during in vitro digestion. The peptide bonds of covalent complex were mainly broken in gastric digestion, while the covalent bonds between tea polyphenols and gluten were completely destroyed in intestinal digestion. In addition, their digestates exhibited excellent antioxidant capability. All results suggest that wheat gluten have potential to prepare functional carrier for transporting active compounds and protecting them during digestion.

Development of an Activity-Based Ratiometric Electrochemical Switch for Direct, Real-Time Sensing of Pantetheinase in Live Cells, Blood, and Urine Samples.

Pantetheinase is a key biomarker for the diagnosis of acute kidney injury and the monitoring of malaria progression. Currently, existing methods for sensing pantetheinase, also known as Vanin-1, show considerable potential but come with certain limitations, including their inability to directly sense analytes in turbid biofluid samples without tedious sample pretreatment. Here, we describe the first activity-based electrochemical probe, termed VaninLP, for convenient and specific direct targeting of pantetheinase activity in turbid liquid biopsy samples. The probe was designed such that cleavage of the pantetheinase amide linkage, triggered by a self-immolative reaction, simultaneously ejects an amino ferrocene reporter. Among the distinctive properties of the VaninLP probe for sensing pantetheinase are its high selectivity, sensitivity, and enzyme affinity, a wide linear concentration range (8-300 ng/mL), and low limit of detection (2.47 ng/mL). The designed probe precisely targeted pantetheinase and was free of interference by other electroactive biological species. We further successfully applied the VaninLP probe to monitor and quantify the activity of pantetheinase on the surfaces of HepG2 tumor cells, blood, and urine samples. Collectively, our findings indicate that VaninLP holds significant promise as a point-of-care tool for diagnosing early-stage kidney injury, as well as monitoring the progression of malaria.

Chloramphenicol Interferes with 50S Ribosomal Subunit Maturation via Direct and Indirect Mechanisms.

Chloramphenicol (CAM), a well-known broad-spectrum antibiotic, inhibits peptide bond formation in bacterial ribosomes. It has been reported to affect ribosome assembly mainly through disrupting the balance of ribosomal proteins. The present study investigates the multifaceted effects of CAM on the maturation of the 50S ribosomal subunit in Escherichia coli (E. coli). Using label-free quantitative mass spectrometry (LFQ-MS), we observed that CAM treatment also leads to the upregulation of assembly factors. Further cryo-electron microscopy (cryo-EM) analysis of the ribosomal precursors characterized the CAM-treatment-accumulated pre-50S intermediates. Heterogeneous reconstruction identified 26 distinct pre-50S intermediates, which were categorized into nine main states based on their structural features. Our structural analysis highlighted that CAM severely impedes the formation of the central protuberance (CP), H89, and H58 during 50S ribosomal subunit maturation. The ELISA assay further demonstrated the direct binding of CAM to the ribosomal precursors, suggesting that the interference with 50S maturation occurs through a combination of direct and indirect mechanisms. These findings provide new insights into the mechanism of the action of CAM and provide a foundation for a better understanding of the assembly landscapes of the ribosome.

Theoretical investigation for the proline effect on peptide fragmentation induced by matrix-assisted laser desorption/ionization in-source decay with an oxidizing matrix

The use of an oxidizing matrix for matrix-assisted laser desorption/ionization in-source decay (MALDI-ISD) specifically induces the cleavage of Cα-C bonds on the peptide backbone, except for bonds located on the N-terminal side of proline residues. To examine the effect of Pro residues on bond cleavage induced by MALDI-ISD with an oxidizing matrix, the small dipeptides AcAA-NH2 and AcAP-NH2 were used as models. As the fragmentation is initiated by electron transfer from the peptide to the oxidizing matrix, the dissociation chemistry of the cation radical forms of the model peptides [AcAA-NH2]+• and [AcAP-NH2]+• was investigated using quantum chemistry calculations. The [AcAA-NH2]+• can produce fragment ions not only due to Cα–C bond cleavage, but also peptide bond cleavage. Quantum chemistry calculations indicated that peptide bond cleavage of [AcAA-NH2]+• occurs more slowly compared to Cα–C bond cleavage. Instead of Cα–C bond cleavage, the bond on the N-terminal side of Pro residue undergoes peptide bond cleavage during MALDI-ISD with an oxidizing matrix, due to the lack of an amide hydrogen in the Pro residue. The [AcAP-NH2]+• undergoes proton migration from the δ-carbon of the Pro residue. Depending on the proton binding site in the peptide cation radical, the peptide bond cleavage of [AcAP-NH2]+• results in the formation of either [b1]+, and [y1]•, or [a1]• and [y1]+. These theoretical results are consistent with experimental findings, and the newly proposed mechanism involving peptide cation radical formation followed by proton migration provides a more accurate model for the MALDI-ISD processes.

Twisted Amide-Mediated Peptide Synthesis.

A robust, practical, and sustainable isomerization-suppressed peptide bond formation via acyl sulfonamide, a twisted amide, is disclosed. Tosyl isocyanate and pentafluorobenzyl bromide were applied in combination to activate the peptide C-terminus, which then reacted with an amine to yield an elongated peptide with high stereochemical purity. Careful analysis of NMR spectra of the active intermediate revealed the presence of an intramolecular hydrogen bond, suggesting that the hydrogen bond suppressed Cα-epimerization during amidation. The isomerization suppression by the intramolecular hydrogen bond is expected to be effective even under high dilution conditions, making the present method a powerful tool for the synthesis of complex macrocyclic peptides. In addition to peptide synthesis, the developed synthetic entry to twisted amides can be applied to the investigation of transition metal-catalyzed N-C bond activation. Moreover, the application to the N-C bond activation returned insight into peptide synthesis, leading to the use of sulfonamide as a protecting group of carboxylic acid that can be orthogonally removed in the presence of other conventional protecting groups.

Breaking Down the Bottlebrush: Atomically Detailed Structural Dynamics of Mucins.

Mucins, the biomolecular components of mucus, are glycoproteins that form a thick physical barrier at all tissue-air interfaces, forming a first line of defense against pathogens. Structural features of mucins and their interactions with other biomolecules remain largely unexplored due to the challenges associated with their high-resolution characterization. Combining limited mass spectrometry glycomics and protein sequencing data, we present all-atom, explicitly solvated molecular dynamics simulations of a major respiratory mucin, MUC5B. We detail key forces and degrees of freedom imposed by the extensive O-glycosylation, which imbue the canonically observed bottlebrush-like structures to these otherwise intrinsically disordered protein backbones. We compare our simulation results to static structures observed in recent scanning tunneling microscopy experiments as well as other published experimental efforts. Our work represents the demonstration of a workflow applied to a mucin example, which we hope will be employed by other groups to investigate the dynamics and interactions of other mucins, which can inform on structural details currently inaccessible to experimental techniques.

Identification and characterization of a novel polyamide hydrolase

The widespread use of non-naturally degradable plastics is causing increasingly serious harm to the environment. Reducing plastic pollutants has become the core of ecological and environment management. Biological methods such as enzymes demonstrate advantages in depolymerizing plastics with mild reaction conditions and recycling of depolymerization products. However, there are few reports on the biological depolymerization of polyamide plastics. In this study, by using 4-nitropropionanilide as the model substrate, we screened against our plastic depolymerase library and obtained a Meiothermus ruber-derived enzyme (MrABH) that can hydrolyze the polyamide bond. We expressed this enzyme in Escherichia coli and purified the protein by affinity chromatography. Furthermore, we investigated the catalytic properties, enzymatic properties, and catalytic products of this enzyme with polyamide as the substrate. MrABH had good stability at pH 8.0-10.0, with the optimal performance at pH 9.0 and 30 ℃. The catalytic performance of this enzyme for ester bonds and amide bonds was similar. MrABH can catalyze the depolymerization of PA6 and PA66 to produce monomers and oligomers, demonstrating the potential to be used in the depolymerization and recycling of polyamide.

Synthesis and BSA binding study of the Cu(II) complex and applications of it to enhance catalytic activity for C(Sp2)-H bond functionalization and for the synthesis of polyhydroquinolines

Among the various copper-catalyzed coupling reactions, C–S and C–N bond-forming reactions have carried off plentiful recognition due to their demand in the synthesis of molecules having biological and pharmaceutical impact. Organo-copper complex has an incontestable supremacy over the other catalytic complex due to its low cost and the use of readily accessible and stable ligands. As a consequence and in continuation of our explorative studies in this direction, an efficient and novel organo-copper complex has been synthesized and characterized by spectroscopic (NMR, FT-IR) and single crystal X-ray diffraction (XRD) methods. The synthesized stable metal complex has fascinating physical, chemical, biological and catalytic properties. In the chemical exploration refer to protein-metal interactions; we have often used Bovine Serum Albumin (BSA) protein. The synthesized copper complex has the potential to form coordinate bonds with functional groups present in BSA, together with amino acid residues and the protein backbone. The binding of metal complexes to BSA has outstanding imputation in medicinal chemistry. For enhancement of the catalytic activity of the organo-copper complex, we have evaluated it in carbon-hetero bond formation reactions where it proffered an influential tool for the establishment of C–S and C–N bonds.

Chitosan Coupled Silver Nanoparticles Electrocatalyst Synthesis and Characterization

This study sought to find a suitable technique for synthesizing and characterizing silver nanoparticles due to its applications in various fields such as nanotechnology and medical. The synthesized silver nanoparticles were characterized using SEM microscopy, FT-IR and UV-Vis spectroscopy. The maximum absorbance from the UV-Vis spectrophotometer showed the formation of silver nanoparticles with λ max of 418 nm. The FTIR analysis envisaged a strong symmetrical stretching at 1400 cm-1 to 1200 cm-1 with the major peaks recorded at 1390 cm-1 and 1380 cm-1, indicating the presence of nitro components in the sample. The signal at 1658 cm−1 corresponded to the amide (C=O) bonds stretching vibrations, at 1089 cm−1 C-O-C bonds and at 564 cm−1 plane with bends NH, plane-out and bends C−O. C-H stretching vibrational signal was noted at 2927 cm−1, and a broader band at 3426 cm−1 with an overlap between the O−H stretching vibration and N−H stretching vibration of the oligosaccharide applied in the capping. The concentration of chitosan on transmittance was done using 0.5%, 1.0%, 1.5% and 2.0% solutions with the results from FT-IR showing elaborate intensity at 2.0 % chitosan capping and the least at 0.5 %. Scanning microscope validated characterized silver nanoparticles morphology at 500nm. The results obtained from SEM depicted a size range of 100 nm with resolutions between 0.5 to 4 nm