Conformational Structure Research Articles

Egg yolk peptide‐iron chelate: preparation, conformational structure, chelating mechanism and stability in vitro

SummaryIn this study, a method to produce iron‐chelating peptides derived from egg yolk proteins was developed and optimised. The egg yolk proteins were enzymolysed and ultrafiltered to prepare egg yolk peptide (EYP), and then the EYP was chelated with Fe to produce egg yolk peptide‐Fe (EYP‐Fe). The optimised mass ratio of peptide to iron, pH, temperature and reaction time were found at 8:1, pH 8.0, 40 °C and 30 min, respectively. The mean particle size of EYP‐Fe was 389.2 ± 2.61 nm, and the chelating ratio was 95.38 ± 1.93%. The measurements of FTIR, X‐ray photoelectron spectroscopy (XPS) and NMR showed that ferrous ions mainly combined with the amino and carboxyl of EYP to form EYP‐Fe. In vitro stability studies have shown that the iron release rate of the EYP‐Fe is maintained at around 5% under alkaline conditions, and there is no significant difference in iron release rate under conditions of 30 °C–80 °C; besides, it has a lower iron release rate (18%) in gastrointestinal digestion compared to FeSO4 (97.93%), indicating that the EYP‐Fe has good heat tolerance, alkalinity and digestion tolerance. The above results provide a scientific basis for the use of EYP‐Fe derived from egg yolk protein as a potential alternative to iron supplements.

Perilla protein isolate exhibits synergistic techno-functionality through modification via sequential dynamic high-pressure microfluidization and enzymatic hydrolysis

Modification of proteins derived from plant sources is crucial for enabling their versatile applications in the food industry. In the present study, structural and functional properties of individual treated perilla protein isolate (PPI) through dynamic high-pressure microfluidization (DHPM) and enzymatic hydrolysis (EH) was compared with their sequential (DHPM-EH) treatment. Native PPI thick, sharp-edged blocks transformed into a collapsed structure with wrinkles after sequential (DHPM-EH) treatment. The synergistic effect between DHPM and EH, during sequential (DHPM-EH) treatment caused greater reduction (91.9%) in PPI particle size as compared to DHPM (87.3%), and EH (84.5%), which enhanced PPI solubility, even at low pH. Above treatments altered the conformational structure of PPI as evident from changes in surface hydrophobicity, free –SH groups conversion into –SS bonds, ultraviolet absorption and fluorescence intensities changes, and decreased α-helix, while increased β-sheets. The sequential (DHPM-EH) treated PPI showed enhanced foaming capacity (×3.59), as well as increased thermal and colloidal stability.

A study of hydrophobic domain formation of polymeric drug precipitation inhibitors in aqueous solution

Despite the widespread use of polymers as precipitation inhibitors in supersaturating drug formulations, the current understanding of their mechanisms of action is still incomplete. Specifically, the role of hydrophobic drug interactions with polymers by considering possible supramolecular conformations in aqueous dispersion is an interesting topic. Accordingly, this study investigated the tendency of polymers to create hydrophobic domains, where lipophilic compounds may nest to support drug solubilisation and supersaturation. Fluorescence spectroscopy with the environment-sensitive probe pyrene was compared with atomistic molecular dynamics simulations of the model drug fenofibrate (FENO). Subsequently, kinetic drug supersaturation and thermodynamic solubility experiments were conducted. As a result, the different polymers showed hydrophobic domain formation to a varying degree and the molecular simulations supported interpretation of fluorescence spectroscopy data. Molecular insights were gained into the conformational structure of how the polymers interacted with FENO in solution phase, which apart from nucleation and crystal growth effects, determined drug concentrations in solution. Notable was that even at the lowest polymer concentration of 0.01 %, w/v, there were polymer-specific solubilisation effects of FENO observed and the resulting reduction in apparent drug supersaturation provided relevant knowledge both from a mechanistic and practical perspective.

Monomeric Esterase: Insights into Cooperative Behavior, Hysteresis/Allokairy.

Herein, we present a novel esterase enzyme, Ade1, isolated from a metagenomic library of Amazonian dark earths soils, demonstrating its broad substrate promiscuity by hydrolyzing ester bonds linked to aliphatic groups. The three-dimensional structure of the enzyme was solved in the presence and absence of substrate (tributyrin), revealing its classification within the α/β-hydrolase superfamily. Despite being a monomeric enzyme, enzymatic assays reveal a cooperative behavior with a sigmoidal profile (initial velocities vs substrate concentrations). Our investigation brings to light the allokairy/hysteresis behavior of Ade1, as evidenced by a transient burst profile during the hydrolysis of substrates such as p-nitrophenyl butyrate and p-nitrophenyl octanoate. Crystal structures of Ade1, coupled with molecular dynamics simulations, unveil the existence of multiple conformational structures within a single molecular state (E̅1). Notably, substrate binding induces a loop closure that traps the substrate in the catalytic site. Upon product release, the cap domain opens simultaneously with structural changes, transitioning the enzyme to a new molecular state (E̅2). This study advances our understanding of hysteresis/allokairy mechanisms, a temporal regulation that appears more pervasive than previously acknowledged and extends its presence to metabolic enzymes. These findings also hold potential implications for addressing human diseases associated with metabolic dysregulation.

Clinical and Radiological Evaluation of Racehorses with Sesamoiditis: Case Series

Background: Sesamoiditis causes intermittent lameness in horses and is characterized by the enlargement of vascular channels, local osteolysis, osteophyte and enthesophyte formation on radiography. This study aimed to report the relationship between the clinical and radiological findings of racehorses diagnosed with sesamoiditis, the treatment applied and long-term results. Methods: The study included a total of 30 Arabian and Thoroughbred racehorses aged 2-7 years diagnosed with sesamoditis based on clinical and radiological examinations. These horses were treated and followed for nine months. Result: Radiographic examination revealed different numbers of enlarged vascular channels in the proximal sesamoid bones in all the cases and osteophytosis (n=3), enthesophytosis (n=9), osteolysis (n=3) and fractures (n=6) in some cases. In addition, low heels were important in 27 cases. The body conformation and low-heeled hoof structure play a role in the development of sesamoiditis in horses and should be considered. As a result, body structure and low heel structure play a role in the development of sesamoiditis in horses and should be considered. This situation should be tried to be corrected by farriers during the foaling period. Sesamoiditis can have a positive prognosis with appropriate treatment and adequate rest, for this reason, treatment should be started in the early period.

Conformal frequency selective rasorber in S, C, X-band with low backward-scattering

In this paper, a polarization-insensitive high transmittance bandpass filter with low radar cross section (RCS) in both S- and X-band is proposed. This is the first study to use the partition layout loading approach for conformal structures with transmissive windows, reducing the operating band RCS. Curved structures have stronger radiation at a smaller angle to the incident wave, and that is how their scattering differs from uniform scattering from flat structures. The structure is divided by analyzing the radiative contribution of different regions. The surface was discussed in regions according to surface angles, and a new partition layout loading method was used to suppress the side currents and decreased backward scattering, achieving a backward RCS reduction of more than 10 dB at 4-8 GHz (66.7%). The bandpass layer operating at 6.9 GHz is designed through equivalent circuit theory. In combination with the lossy layer, absorption above 0.8 at 3.7-5.6 GHz and 9.1-12.5 GHz was achieved. Further, the structure was fashioned into a curved surface with varying curvature, demonstrating its effective absorption and transmission properties across different curvatures. A 15 × 15 cell structure was designed and fabricated, and there was good agreement between the test results and simulation results. The proposed structure has important applications in radomes, conformal structures, and electromagnetic shielding.

Ru(II)-Arene Complexes of Curcumin and Bisdesmethoxycurcumin Metabolites.

Curcuminoids and their complexes continue to attract attention in medicinal chemistry, but little attention has been given to their metabolic derivatives. Here, the first examples of (arene)Ru(II) complexes with curcuminoid metabolites, tetrahydrocurcumin (THcurcH), and tetrahydrobisdesmethoxycurcumin (THbdcurcH) were prepared and characterized. The neutral complexes [Ru(arene)(THcurc)Cl] and [Ru(arene)(THbdcurc)Cl] (arene = cymene, benzene, or hexamethylbenzene) were characterized by NMR spectroscopy and ESI mass spectrometry, and the crystal structures of the three complexes were determined by X-ray diffraction analysis. Compared to curcuminoids, these metabolites lose their conjugated double bond system responsible for their planarity, showing unique closed conformation structures. Both closed and open conformations have been analyzed and rationalized by using density functional theory (DFT). The cytotoxicity of the complexes was evaluated in vitro against human ovarian carcinoma cells (A2780 and A2780cisR), human breast adenocarcinoma cells (MCF-7 and MCF-7CR), as well as against non-tumorigenic human embryonic kidney cells (HEK293) and human breast (MCF-10A) cells and compared to the free ligands, cisplatin, and RAPTA-C. There is a correlation between cellular uptake and the cytotoxicity of the compounds, suggesting that cellular uptake and binding to nuclear DNA may be the major pathway for cytotoxicity. However, the levels of complex binding to DNA do not strictly correlate with the cytotoxic potency, indicating that other mechanisms are also involved. In addition, treatment of MCF-7 cells with [Ru(cym)(THcurc)Cl] showed a significant decrease in p62 protein levels, which is generally assumed as a noncisplatin-like mechanism of action involving autophagy. Hence, a cisplatin- and a noncisplatin-like concerted mechanism of action, involving both apoptosis and autophagy, is possible.

Benzoyl Valine Quasiracemates: Pairing CF3 Quasienantiomers with H to t-Butyl.

Understanding the interplay of structural features responsible for molecular assembly is essential for molecular crystal engineering. When assembling molecules with encoded motifs, first choice supramolecular strategies almost always include robust directional nonbonded contacts. Quasiracemic materials, considered near racemates since cocrystallization occurs with chemically unique components, lack a molecular framework or functional group restrictions, highlighting the importance of molecular shape to molecular assembly. Recently, our group reported quasiracemates derived from benzoyl leucine/phenylalanine derivatives with two points of chemical difference. In this study, we modified the chemical framework with valine and increased the scope of the work by imposing a larger variance in the side chain substituents. Pairing a CF3 component with quasienantiomers that differ iteratively from hydrogen to t-butyl offers an important view into the supramolecular landscape of these materials. Single-crystal X-ray crystallography and lattice energy assessments, coupled with conformational and crystal structure similarity searches, show an elevated degree of isomorphism for many of the targeted 17 racemates and quasiracemates. These benzoyl amino acid molecular architectures create extended hydrogen-bond patterns in the crystal that provide enhanced opportunities to study the shape space and molecular recognition profiles for a diverse family of quasienantiomeric components.

Evaluation of digestibility, solubility, and surface properties of trehalose-conjugated quinoa proteins prepared via pH shifting technique

Soluble trehalose-conjugated quinoa proteins (T-QPs) were effectively prepared using the pH-shifting mechanism. The structural properties of the T-QPs were evaluated using a comparative evaluation, which included analyzing the amide I, surface charge and hydrophobicity, protein conformation, thermal stability, and protein structures. The results suggested that the development of the T-QPs was influenced mainly by no-covalent bonds. These interactions significantly influenced (P < 0.05) the quinoa proteins' conformation and higher-protein structure. T-QP had significant (P < 0.05) surface properties. Furthermore, the T-QPs exhibited improved solubility (79.7 to 88.4%) and digestibility (79.8 to 85.1%). Therefore, quinoa protein proved an excellent plant-based protein for conjugation with disaccharides. These findings provide significant insight into the potential development of modified proteins with enhanced solubility and digestibility by creating trehalose-conjugated plant-based proteins.

The influence of anions in the ionic liquid-water mixtures on the conformational structures of emeraldine base and emeraldine salt form of polyaniline

The development of antifouling membranes for water filtration applications is challenging. Conducting polymers can show enhanced antifouling characteristics by blending with various polymers, nanomaterials, and Ionic liquids (ILs). In this paper, we perform an all-atom molecular dynamics simulation on a conducting polymer polyaniline (PANI) immersed in IL-water mixtures. Two forms of PANI were considered, namely Emeraldine base (EB) and Emeraldine salt (ES) as well as two different water-mixed ILs are considered namely (a) 1-ethyl-3-methyl imidazolium [EMIM]+ hexafluorophosphate [PF6]- and (b) 1-ethyl-3-methyl imidazolium [EMIM]+ tetra-fluoroborate [BF4]-. We present various intra- and inter-molecular structural properties, solvation thermodynamics, and dynamic properties. We observe that with an increase in IL concentration, the radius of gyration (Rg) value shows a decrease for ES in pure state in both ILs; on the other hand, we see a minimal increase in the Rg values of EB in both ILs. The dihedral angle distribution analysis shows a combination of gauche and trans state for ES, whereas trans state is more pronounced for the case of EB in both water-IL mixtures. The radial distribution function (RDF) analysis between the ortho, meta carbons of the benzene rings, and the amine groups on ES with [BF4]- and [PF4]- show significant structural peaks. On the other hand, EB and ES show lower interaction with the water molecules. The number of hydrogen bonds (h-bonds) between polymer and water is higher for EB than ES in both IL-water mixtures. The hydrogen bond lifetime (τ) values show one-fold higher values for EB than ES. The self-diffusion coefficient (D) values of water show a decrease with an increase in IL concentration. The thermodynamic properties solvation enthalpy (ΔH) and excess molar volume (VmE) for both ES and EB show a more favorable solvation in [EMIM]+[BF4]- when compared to [EMIM]+[PF6]- with an increase in IL concentration. These observations are crucial for selecting ILs and designing sustainable polymers for antifouling membranes.

Synergistic regulation of chloride anion recognition using a triple-functional sites receptor with two different cationic effectors.

The synergistic regulation of the multi-functional sites on one receptor molecule with different cationic effectors for anion recognition is scarce to be well understood from the experiment and theory. In this work, a new anion receptor with three functional zones including ether hole, biurea and double bipyridine groups (EUPR) is designed expecting to enhance the chloride anion recognition together with a rational synthesis path being proposed based on four simple and mature organic reaction steps. The conformational structures of the designed receptor EUPR and the binding behaviors for three kinds of ions (Cl-, Na+, and Ag+) are deeply investigated by using density functional theoretical calculations. It is found that Cl- binding via the hydrogen bond interaction can be significantly enhanced and synergistically regulated by the two kinds of cations and the corresponding conformational changes of receptor EUPR. Especially, the conformational pre-organization of receptor caused by the encapsulation of sodium ion into ether hole is benefit to the binding for Cl- in both thermodynamics and kinetics. Na+ binding, in turn, can ever be enhanced by chloride anion, whereas it seems that Ag+ binding cannot always be enhanced by chloride anion, reflecting an electrical complementary matching and mutual enhancement effect for different counter ions. Moreover, solvent effect calculations indicate that EUPR may be an ideal candidate structure for Cl- recognition by strategy of counter ion enhancement in water. Additionally, a visual study of intermolecular noncovalent interaction (NCI) and molecular electrostatic potential (ESP) are used for the analysis on the nature of interactions between receptor and bound ions.

Accurate Structures and Rotational Constants of Steroid Hormones at DFT Cost: Androsterone, Testosterone, Estrone, β-Estradiol, and Estriol.

A comprehensive analysis of the structural, conformational, and spectroscopic properties in the gas phase has been performed for five prototypical steroid hormones, namely, androsterone, testosterone, estrone, β-estradiol, and estriol. The revDSD-PBEP86 double-hybrid functional in conjunction with the D3BJ empirical dispersion and a suitable triple-ζ basis set provides accurate conformational energies and equilibrium molecular structures, with the latter being further improved by proper account of core-valence correlation. Average deviations within 0.1% between computed and experimental ground state rotational constants are reached when adding to those equilibrium values vibrational corrections obtained at the cost of standard harmonic frequencies thanks to the use of a new computational tool. Together with the intrinsic interest of the studied hormones, the accuracy of the results obtained at DFT cost for molecules containing about 50 atoms paves the way toward the accurate investigations of other flexible bricks of life.

Embedding lattice structures into ship hulls for structural optimization and additive manufacturing

Additive manufacturing (AM) has been making inroads into the shipbuilding industry. The maritime sector has recognized the potential benefits of AM in terms of cost savings, design flexibility, and rapid prototyping. Lattice structures, known for their vast applications in AM and associated benefits like lightweight design, energy efficiency, and improved material usage, serve as a focal point in this shifting landscape.This paper presents a pioneering approach to integrating lattice structures into shipbuilding via AM, specifically for supporting ship volumes. The method introduces algorithms to create both conformal and uniform lattice structures for structural optimization. According to the case studies in this work, ship models with lattice structures have superior structural properties compared to conventional support elements.

Abstract 5774: Are 19del and L858R really not the same disease entities

Abstract IntroductionThe similarities and differences between the two subtypes of common epidermal growth factor receptor (EGFR) mutations have been recognized by clinicians, but actual treatment strategies remain unchanged. The L858R mutation can be explained by the pharmacological conformational plasticity of the receptor protein and other co-occurring mutations, which may be subtypes of EGFR mutations or non-EGFR mutations, and differences in downstream signaling pathways. As long as we know that molecular differences lead to biological differences, it is a challenge for all of us that our treatment strategies must changeWe investigated the RWD, conformational structure and RNA expression profile about two types of common mutations in the mEGFR+ NSCLC patients.MethodWe collected the medical information for stage I-IIIA mEGFR+ NSCLC patients and explored the conformational structure by crystalized radiologic technique. And we performed RNA expression assay using multiplex IF and High-through-output Profiling. ResultOverall, the static structures of wild type (WT), L858R, and 19del (ΔL747-E749) EGFR did not show any significant differences. However, the difference in the static structure between WT-19del and L858R-19del was subtly greater than that of WT-L858R. In addition, further analyses demonstrated no significant structural differences in the phosphorylation sites. However, it should be noted that proteins do not exist as static structures in vivo, and they have a dynamic, flexible structure that changes over time, i.e., plasticity of proteins. Therefore, we investigated the X-ray B-factor value, which is an indicator of flexibility, dynamics, and plasticity of proteins. As expected, the loop or disordered regions mainly shows higher B-factor values, which indicates an active structure, highly changeable and dynamic. Together, the three types of the EGFR protein manifest wholly similar B-factor values, while several local regions present appreciably distinct B-factors. Physical properties such as the dynamic structure may affect intermolecular recognition of EGFR proteins and their function Recent biochemical and biophysical evidence suggests that oncogenic mutations have an impact on the conformational dynamics of enzymesConclusionIn conclusion, our results suggest that Patients with 19del and L858R mutations demonstrated a different clinical course. It is necessary to consider the dynamic structural characteristics and functional differences of EGFR membrane proteins. Citation Format: Yunseok Heo, Joo Ri Kim, Yeoun Eun Sung, Seoree Kim, Chan Kwon Jung, Jeong-Oh Kim, Jeong-yeon Shin, Guk Jin Lee, Sang hoon Chun, Seong Hyeon Bu, Young Ho Lee, Jin Hyoung Kang. Are 19del and L858R really not the same disease entities [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5774.

Abstract 3737: Molecular and early clinical characterization of the anti-CD73 antibody S095024 (Sym024)

Abstract Background: Adenosine signaling is a central immunosuppressive mechanism affecting a broad set of immune cell types. Adenosine is generated from extracellular ATP by a group of ectonucleotidases including CD39 and CD73. Suppressing the adenosine pathway via CD73 blockade may enhance the potential of checkpoint inhibitor therapies.S095024 (Sym024) is a fully human, effector-function attenuated antibody that binds to human and cynomolgus CD73 with sub-nM affinity. Methods: Preclinically, the stoichiometry and conformational structure of the binding interaction between CD73 and S095024 was assessed by SEC-MALS and cryo-EM and the ability of S095024 to inhibit CD73 activity was done in vitro covering 3-, 6- and 24-hour incubation periods. The clinical safety, tolerability, pharmacokinetics, and pharmacodynamics of S095024 alone or in combination with Sym021, an anti-PD1 antibody, was investigated in a first-in-human study (NCT04672434) in patients with selected types of advanced solid tumors. Following assessment of single agent S095024 (100 to 1500 mg IV Q2W) in part I, the safety and tolerability of S095024 (300 to 1500 mg IV Q2W) was assessed in combination with Sym021 (200 mg IV Q2W) in part II. A part IIa was added: patients received 3000 mg IV Q2W of S095024 in Cycle 1, followed by 3000 mg S095024 + 200 mg Sym021 from Cycle 2 onwards. Results: Structural data indicate that S095024 binds to CD73 in a unique configuration by bridging the two monomers of the molecule, interacting in a 1:1 stoichiometry and effectively preventing the conformational state cycling required for catalysis. Functional data using a 20x cell line panel harboring a broad range of CD73 expression levels demonstrates that this interaction modus results in deep enzymatic inhibition. As of 12 Oct 2023, 43 patients have been treated with, S095024 in the FIH study. S095024, as a single agent (N=18) and in combination with PD-1 blockade (N=25) was well tolerated across all dose levels. The most frequent treatment emergent adverse events (≥15% patients) were fatigue, nausea, diarrhea, dyspnea, and vomiting. A dose proportional increase in drug exposure, both in monotherapy and combination, was observed starting at 900 mg. Target engagement assessed both peripherally (free soluble CD73) and intra-tumorally (enzymatic activity), showed a sustained decrease in free soluble CD73 in blood at dose levels ≥1500 mg and dose-dependent CD73 modulation, with &amp;gt;80% inhibition reached at ≥1500 mg in tumor biopsies. Conclusions: These findings reveal the potential of S095024 (Sym024) to prevent adenosine-mediated tumor evasion and support further clinical investigation. Citation Format: Anna Spreafico, Jordi R. Ahnert, David Sommerhalder, Maria Almena-Carrasco, Najah Harouki Crochemore, Xenophon Ianopulos, Janus S. Jakobsen, Emily Armbruster, Audrey Delmas, Amédée des Georges, Camilla Fröhlich, Julia Geronimi, Michael M. Grandal, Randi W. Hansen, Johan Lantto, Julie Legrand, Franck Levasseur, Matteo Riva, Christelle Rodrigues, Vanessa Seif, Vasileios Askoxylakis, Nehal Lakhani. Molecular and early clinical characterization of the anti-CD73 antibody S095024 (Sym024) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3737.

Novel conformal sandwich lattice structures: Design concept, fabrication and mechanical properties

A novel conformal sandwich lattice is proposed by introducing the design concept of bioinspired sandwich structures into the microstructure design of triply periodic minimal surface (TPMS) lattices, and the mechanical properties of the conformal sandwich lattice (P-SC) with P-TPMS lattice skins and simple cubic (SC) plate lattice cores are investigated numerically and experimentally. The P-SC specimen manufactured by the laser powder bed fusion (L-PBF) with glass bead-filled polyamide composite exhibits negligible anisotropy in its mechanical properties, as confirmed by tensile tests conducted on specimens fabricated at various build orientations. The elastic properties of the P-SC can be widely tailored by modifying the structural parameters. Especially, the anisotropic index can be tailored to obtain an elastically-isotropic P-SC sandwich lattice. Additionally, the P-SC exhibits superior elastic properties and energy absorption compared with the conventional lattices. The findings provide insights into the design flexibility of advanced high-performance structural materials for complex engineering applications.

N-Heterocyclic carbene-catalyzed enantioselective synthesis of planar-chiral cyclophanes via dynamic kinetic resolution

Planar-chiral cyclophanes have gained considerable concerns for drug discovery due to their unique conformational strain and 3D structure. However, the enantioselective synthesis of planar-chiral cyclophanes is a long-standing challenge for the synthetic community. We herein describe an N-heterocyclic carbene (NHC)-catalyzed asymmetric construction of planar-chiral cyclophanes. This transformation occurs through a dynamic kinetic resolution (DKR) process to convert racemic substrates into planar-chiral macrocycle scaffolds in good to high yields with high to excellent enantioselectivities. The ansa chain length and aromatic ring substituent size is crucial to achieve the DKR approach. Controlled experiments and DFT calculations were performed to clarify the DKR process.

Canonical reductions of the TED equation: integrable deformations of heavenly-type equations

Natural classes of integrability-preserving reductions of a 4+4-dimensional generalisation (TED equation) of the general heavenly equation are recorded. In particular, these reductions lead to integrable ‘deformations’ of various other avatars of the heavenly equation governing self-dual Einstein spaces. The known deformed heavenly equations which give rise to half-flat conformal structures are retrieved in this manner. Moreover, Plebański’s link between the first and second heavenly equations is extended to their deformed counterparts.

Effect of different iron ratios on interaction and thermodynamic stability of bound whey protein isolate

Whey protein isolates (WPI) are known to have mineral-binding capacity to promote iron absorption. The aim of this study was to investigate the effect of iron ratio on the conformational structure of iron-bound whey protein isolate (WPI-Fe) and its thermodynamic stability. It was shown that the iron to protein ratio affects both the iron binding capacity of WPI and the iron valence state on the surface of WPI-Fe complexes. As the iron content increases, aggregation between protein molecules occurs. In addition, WPI-Fe nanoparticles have thermodynamic stability and Fe2+ has a high affinity with WPI for spontaneous exothermic reactions. This study demonstrates that WPI-Fe complexes can be used to efficiently deliver high-quality iron source (Fe2+) for future iron supplements.

FT-IR, FT-raman and UV spectra and ab initio HF and DFT study of conformational analysis, molecular structure and properties of ortho- meta– and para–chlorophenylboronic acid isomers

In this study, the FT-IR, FT-Raman, and UV–Vis spectroscopic properties of three monosubstituted phenylboronic acid derivatives: ortho-chlorophenylboronic acid (o-ClPhBA), meta-chlorophenylboronic acid (m-ClPhBA) and para-chlorophenylboronic acid (p-ClPhBA) molecules are investigated both experimentally and theoretically using Density Functional Theory (B3LYP) and Hartree Fock (HF). In order to find the stable possible conformations of the compounds, the conformational analysis was carried out by running potential energy surface (PES) scan by means of rotation of two structural parameters, the dihedral angles indicated as φ2 (C6–B–O1–H1A) and φ3 (C6–B–O2–H2A), varying from −180° to 180° with an increment of 10° using B3LYP/6-31G level of theory. Also, to determinate the most stable conformer for all the molecules, potential energy curve (PEC) the stable possible conformations on PES scan were investigated as a function of φ1 (C1-C6–B–O1) dihedral angle from 0° up to 180° with an increment of 10° using B3LYP/6–311++G(d,p) and HF/6–311++G(d,p) level of theory. For all the studied compounds, two conformational structures (conformer anti-anti, syn-syn) that did not have imaginary frequency values outside the equilibrium state (conformer anti-syn) were detected theoretically at the both methods.Due to their conformational flexibility, the relative stabilities of the anti-syn, anti-anti, and syn-syn conformers of o-ClPhBA, m-ClPhBA, and p-ClPhBA are 0.0, 4.66, and 6.76 kcal/mol, respectively, at the B3LYP/6–311++G(d,p) level of theory. For the HF/6–311++G(d,p) level of theory, the relative stabilities are 0.00, 4.54, and 6.11 kcal/mol for o-ClPhBA; 0.00, 3.98, and 1.51 kcal/mol for m-ClPhBA; and 0.00, 4.10, and 1.44 kcal/mol for p-ClPhBA, respectively. Some of the determined stable conformations of these molecules are different in symmetry groups. It was observed that the increase in the symmetry was effective in the of molecular properties, especially for vibrational frequencies. The structural parameter, dipole moments (μ), vibrational frequencies, polarizability (α), hyperpolarizability (β), the highest occupied molecular orbital (HOMO), and the lowest unoccupied molecular orbital (LUMO) of the stable conformers were calculated by using Ab initio HF/6–311++G(d,p) and DFT/B3LYP/6–311++G(d,p) level of theory. The assignments of fundamental vibrational modes of the studied molecule were performed based on total energy distribution (TED) analysis.