Hydrophobic Content Research Articles

How hydrophobicity, side chains, and salt affect the dimensions of disordered proteins.

Despite the generally accepted role of the hydrophobic effect as the driving force for folding, many intrinsically disordered proteins (IDPs), including those with hydrophobic content typical of foldable proteins, behave nearly as self-avoiding random walks (SARWs) under physiological conditions. Here, we tested how temperature and ionic conditions influence the dimensions of the N-terminal domain of pertactin (PNt), an IDP with an amino acid composition typical of folded proteins. While PNt contracts somewhat with temperature, it nevertheless remains expanded over 10-58°C, with a Flory exponent, ν, >0.50. Both low and high ionic strength also produce contraction in PNt, but this contraction is mitigated by reducing charge segregation. With 46% glycine and low hydrophobicity, the reduced form of snow flea anti-freeze protein (red-sfAFP) is unaffected by temperature and ionic strength and persists as a near-SARW, ν ~ 0.54, arguing that the thermal contraction of PNt is due to stronger interactions between hydrophobic side chains. Additionally, red-sfAFP is a proxy for the polypeptide backbone, which has been thought to collapse in water. Increasing the glycine segregation in red-sfAFP had minimal effect on ν. Water remained a good solvent even with 21 consecutive glycine residues (ν > 0.5), and red-sfAFP variants lacked stable backbone hydrogen bonds according to hydrogen exchange. Similarly, changing glycine segregation has little impact on ν in other glycine-rich proteins. These findings underscore the generality that many disordered states can be expanded and unstructured, and that the hydrophobic effect alone is insufficient to drive significant chain collapse for typical protein sequences.

Exploring the impact of malondialdehyde and 4-hydroxy-2-nonena on myofibrillar protein structure: A proteomic analysis

In this investigation, the impacts of malondialdehyde (MDA), 4-hydroxy-2-nonena (HNE), and their combinations on the structural characteristics of myofibrillar proteins (MP) were examined using endogenous fluorescence, Fourier transform infrared spectrum (FTIR) and Sodium Dodecyl Sulfate Polyacrylamide Gel Electrophoresis (SDS-PAGE). The potential binding mechanisms were also explored using LC-MS/MS and proteomics techniques. The findings indicated that various reactive carbonyl compounds (RCCs) displayed distinct oxidation performances in the oxidation of myofibrillar proteins. Samples containing HNE (HMP and MHMP groups) exhibited a more pronounced ability to oxidize MP than those containing MDA, as evidenced by their higher carbonyl content and lower sulfhydryl content. The MHMP group demonstrated the greatest surface hydrophobicity and Schiff base content but the lowest fluorescence intensity, suggesting that MDA and HNE synergistically altered MP conformation. Moreover, the alteration by RCCs notably modified the secondary structure of MP. Among these, HMP triggered the unfolding of MP molecules, resulting in the lowest α-helix and highest β-sheet ratio. The SDS‒PAGE results suggested that MDA oxidation promoted the crosslinking of MP molecules. At the same time, HNE caused the degradation of MP, as indicated by the decrease in the intensity of the high-molecular-weight bands. Proteomic analysis suggested that lysine residues distributed in the tail region of myosin were the main binding sites for MDA, whereas HNE preferentially modified methionine located at the myosin head. Additionally, HNE-induced protein degradation dominated RCC-induced oxidation reactions. These findings provide deeper insights into the mechanisms underlying quality changes induced by lipid oxidation products in MP-based food systems.

Amphiphilic Magnetic Particles Dispersed in Water and Oil for the Removal of Hydrophilic and Hydrophobic Microplastics.

The study explores the synthesis and versatile properties of amphiphilic magnetic particles (AMPs) achieved through sequential coatings. Modulating the hydrophobic content in the synthesis process allows for the formation of hydrophilic, amphiphilic, and hydrophobic magnetic particles, with stable AMPs synthesis achieved at a ratio of hydrophilic to hydrophobic portions of approximately 71 to 29%. These AMPs exhibited outstanding dispersion in both oil and water within an oil/water mixture. Polyethylenimine in the AMP primarily enhances the removal of hydrophilic microparticles and facilitates dispersion in water. On the other hand, octadecylamine is specifically designed for the effective elimination of hydrophobic microparticles and their dispersion in oil. AMPs demonstrated effective removal capabilities for both hydrophilic and hydrophobic microparticles in water as well as hydrophobic microparticles in 100% oil. Our approach is also suited for eliminating hydrophobic microparticles dispersed in small quantities of oil floating on large bodies of water in real-world situations.

Comparison of Alternative Protein Hydrogels for Delivering Myricetin: Interaction Mechanism and Stability Evaluation.

Food protein carriers from different sources might have distinct stabilizing and enhancing effects on the same small molecule. To elucidate the molecular mechanism, five different sourced proteins including soy protein isolates (SPIs), whey protein isolates (WPIs), edible dock protein (EDP), Tenebrio molitor protein (TMP), and yeast protein (YP) were used to prepare protein hydrogels for delivering myricetin (Myr). The results suggested that the loading capacity order of Myr in different protein hydrogels was EDP (11.5%) > WPI (9.3%) > TMP (8.9%) > YP (8.0%) > SPI (7.6%), which was consistent with the sequence of binding affinity between Myr and different proteins. Among five protein hydrogels, EDP had an optimum loading ability since it possessed the highest hydrophobic amino acid content (45.52%) and thus provided a broad hydrophobic cavity for loading Myr. In addition, these protein-Myr composite hydrogels displayed the core-shell structure, wherein hydrogen bonding and hydrophobic interaction were the primary binding forces between proteins and Myr. Moreover, the thermal stability, storage stability, and sustained-release properties of Myr were significantly enhanced via these protein delivery systems. These findings can provide scientific guidance for deeper utilization of food alternative protein sources.

Removal of antibiotics, bacterial toxicity, and occurrence of antibiotic resistance genes in secondary hospital effluents treated with granular activated carbon and the impact of preceding chlorination

This comprehensive investigation highlighted the complex adsorption behaviors of antibiotics onto granular activated carbon (GAC), the effectiveness of this adsorption in reducing bacterial toxicity, and the reduction of antibiotic resistance genes (ARGs) and antibiotic resistant bacteria (ARB) in hospital wastewater (HWW) effluents. Six GACs were characterized for their physicochemical properties, and their ability to adsorb six antibiotics in the background matrix of actual HWW was evaluated. Coconut shell-derived GAC (CoU), which had the highest hydrophobicity and lowest content of oxygen-containing acidic functional groups, demonstrated the highest adsorption capacities for the tested antibiotics. Bacterial toxicity tests revealed that GACs could eliminate the bacterial toxicity from antibiotic intermediates present in chlorinated HWW. By contrast, the bacterial toxicity could not be removed by GACs in non-chlorinated HWW due to the greater presence of intermediate components identified by LC-MS/MS. The intraparticle diffusion coefficient of antibiotics adsorbed onto CoU could be calculated by adsorption kinetics derived from the linear driving force model and the homogenous intraparticle diffusion model associated with the linear adsorption isotherms (0–150 μg/L). Meropenem and sulfamethoxazole exhibited the highest adsorption capacities in a single-solute solution compared to penicillin G, ampicillin, cetazidime, and ciprofloxacin. However, the greater adsorption capacities of meropenem and sulfamethoxazole disappeared in mixed-solute solutions, indicating the lowest adsorption competition. GAC can eliminate most ARGs while also promoting the growth of some ARB. Chlorination (free chlorine residues at 0.5 mg Cl2/L) did not significantly affect the overall composition of ARGs and ARB in HWW. However, the accumulation of ARGs and ARB on GAC in fixed bed columns was lower in chlorinated HWW than in non-chlorinated HWW due to an increase in the adsorption of intermediates.

Effect of limited hydrolysis with endopeptidase on bitterness properties of wheat gluten hydrolysates

The application of limited hydrolysis on wheat gluten (WG) has been found to be a highly effective method for improving a wide range of functional properties associated with plant protein. However, the bitter peptides formed during this process have an unpleasant bitterness. To provide a theoretical framework for de-bittering techniques, this study examined the modulation of bitterness intensity in wheat gluten hydrolysates (WGHs) by manipulating enzyme cleavage sites and degree of hydrolysis (DH). It was found that the bitter peptide's release content increased significantly, and the bitterness threshold decreased markedly with increasing DH. Furthermore, the structure-bitterness threshold association of bitter peptides was investigated. The results indicated that peptide segments in molecular weights (MW) from 500 to 1000 exhibited the greatest influence on bitterness threshold compared to peptides with other MWs. The percentage of total hydrophobic amino acid content and position of some hydrophobic amino acids in the amino acid sequence had a significant effect on the bitterness threshold. Finally, 47 peptides were identified by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) analysis. These peptides were mainly small peptides with less than 13 amino acid residues and MW below 1500 Da, and most of them had Q values higher than 5855 J/mol.

Cowhide gelatin peptide as a source of antioxidants for inhibiting the deterioration of pudding quality during storage

To investigate the effect of gelatin peptide on the inhibition of quality deterioration in stored pudding, gelatin peptide with antioxidant properties was added to pudding products. For this purpose, a pudding recipe containing gelatin peptides was created. The gelatin peptides were characterized based on their antioxidant activity and protein structure. It was found that gelatin peptides had better antioxidant properties, lower thermal stability and crystallinity, higher hydrophobic amino acid content, and greater surface hydrogen bond exposure than commercially available peptides. Properties such as the pH, colony growth, and sensory characteristics of the pudding were characterized at 4 °C and 25 °C. The results showed that the addition of 0.5–1.0 % gelatin peptide to pudding was capable of significantly (P< 0.05) slowing down the decline in pH and sensory scores of the pudding and significantly inhibiting colony growth. It could prolong its storage life by five days at 4 °C and three days at 25 °C.

Effects of Matrix Structure on Protein Digestibility and Antioxidant Property of Different Soybean Curds During In Vitro Digestion.

This study compared the three most common types of tofu (soybean curd), which were prepared by using magnesium chloride (MgCl2 tofu), calcium sulfate (CaSO4 tofu), and glucono-δ-lactone (GDL tofu) coagulants. The results showed that GDL tofu had a higher water holding capacity than MgCl2 tofu and CaSO4 tofu, which was attributed to its high surface hydrophobicity and disulfide bond content. GDL tofu possessed the lowest firmness, gumminess, and chewiness, along with a uniform network structure and a thin protein matrix. In contrast, MgCl2 tofu exhibited an inhomogeneous network structure with a thick protein matrix. Combining the results of protein hydrolysis degree, SDS-PAGE, and free amino acids during in vitro digestion, it was indicated that the degree of protein digestion in GDL tofu was the highest. After intestinal digestion, GDL tofu had the highest total phenolic content, ferric reducing antioxidant power, and DPPH value. These results demonstrated the superior protein digestibility and antioxidant property of GDL tofu during in vitro digestion due to its structural characteristics that facilitate enzyme diffusion in the matrix. The findings offer insight into the protein digestibility and antioxidant properties of different types of tofu during digestion from structural characteristic perspective and valuable reference information for consumer dietary nutrition.

Lentil protein isolate (Lens culinaris) subjected to ultrasound treatment combined or not with heat-treatment: structural characterization and ability to stabilize high internal phase emulsions

This study evaluated the effect of ultrasound treatment combined or not with heat treatment applied to lentil protein isolate (LPI) aiming to enhance its ability to stabilize high internal phase emulsions (HIPE). LPI dispersion (2%, w/w) was ultrasound-treated at 60% (UA) and 70% (UB) amplitude for 7 min; these samples were subjected to and then heat treatments at 70 °C (UAT70 and UBT70, respectively) or 80 °C (UAT80 and UBT80, respectively) for 20 min. HIPEs were produced with 25% untreated and treated LPI dispersions and 75% soybean oil using a rotor–stator (15,500 rpm/1 min). The LPI dispersions were evaluated for particle size, solubility, differential scanning calorimetry, electrophoresis, secondary structure estimation (circular dichroism and FT-IR), intrinsic fluorescence, surface hydrophobicity, and free sulfhydryl groups content. The HIPEs were evaluated for droplet size, morphology, rheology, centrifugal stability, and the Turbiscan test. Ultrasound treatment decreased LPI dispersions’ particle size (∼80%) and increased solubility (∼90%). Intrinsic fluorescence and surface hydrophobicity confirmed LPI modification due to the exposure to hydrophobic patches. The combination of ultrasound and heat treatments resulted in a reduction in the free sulfhydryl group content of LPI. HIPEs produced with ultrasound-heat-treated LPI had a lower droplet size distribution mode, greater oil retention values in the HIPE structure (> 98%), lower Turbiscan stability index (< 2), and a firmer and more homogeneous appearance compared to HIPE produced with untreated LPI, indicating higher stability for the HIPEs stabilized by treated LPI. Therefore, combining ultrasound and heat treatments could be an effective method for the functional modification of lentil proteins, allowing their application as HIPE emulsifiers.

Antioxidant and angiotensin converting enzyme inhibitory activities of red lionfish (Pterois volitans L.) muscle protein hydrolysates obtained using pepsin-pancreatin system

Despite being an invasive species and representing a threat in the area, red lionfish (Pterois volitans L.) meat is valued for its pleasant taste and high protein content. The objective of the present work was to evaluate the angiotensin converting enzyme inhibition (ACE-I) and the antioxidant activities of red lionfish muscle protein hydrolysates in vitro. Hydrolysates were obtained using the pepsin-pancreatin system, and their degree of hydrolysis (DH), electrophoretic, and amino acid profile were determined. Subsequently, their ACE-I and ABTS+ radical scavenging activity were evaluated, selecting those with the highest response. The highest DH (66.1%) was found in the hydrolysate obtained at 120 min of reaction time (H120); electrophoresis revealed the action of the enzymes on the muscle proteins. The highest bioactivities occurred during hydrolysis with pepsin for 60 min (H60), obtaining the highest ACE-I of 68.8% (evaluated with 500 µg protein) with a DH of 16.8%, ACE-I related amino acid content of 33.6%, and hydrophobic amino acid content of 42.9%. With the 30 min hydrolysates (H30), the highest Trolox equivalent antioxidant capacity of 60.3 mM/mg protein was obtained with 18.4% DH and 22.1% radical scavenger amino acids; its comparison with H120 proved that higher DH did not produce a greater response in ABTS+ radical scavenging activity, DPPH, reducing power, and copper chelation assays; with β-carotene bleaching being the exception. Therefore, it can be concluded that red lionfish muscle hydrolysates could be a promising source of peptides with antihypertensive and antioxidant properties, and can be suitable as functional ingredients.

Characterization of the Effects of Low-Sodium Salt Substitution on Sensory Quality, Protein Oxidation, and Hydrolysis of Air-Dried Chicken Meat and Its Molecular Mechanisms Based on Tandem Mass Tagging-Labeled Quantitative Proteomics.

The effects of low-sodium salt mixture substitution on the sensory quality, protein oxidation, and hydrolysis of air-dried chicken and its molecular mechanisms were investigated based on tandem mass tagging (TMT) quantitative proteomics. The composite salt formulated with 1.6% KCl, 0.8% MgCl2, and 5.6% NaCl was found to improve the freshness and texture quality scores. Low-sodium salt mixture substitution significantly decreased the carbonyl content (1.52 nmol/mg), surface hydrophobicity (102.58 μg), and dimeric tyrosine content (2.69 A.U.), and significantly increased the sulfhydryl content (74.46 nmol/mg) and tryptophan fluorescence intensity, suggesting that protein oxidation was inhibited. Furthermore, low-sodium salt mixture substitution significantly increased the protein hydrolysis index (0.067), and cathepsin B and L activities (102.13 U/g and 349.25 U/g), suggesting that protein hydrolysis was facilitated. The correlation results showed that changes in the degree of protein hydrolysis and protein oxidation were closely related to sensory quality. TMT quantitative proteomics indicated that the degradation of myosin and titin as well as changes in the activities of the enzymes, CNDP2, DPP7, ABHD12B, FADH2A, and AASS, were responsible for the changes in the taste quality. In addition, CNDP2, ALDH1A1, and NMNAT1 are key enzymes that reduce protein oxidation. Overall, KCl and MgCl2 composite salt substitution is an effective method for producing low-sodium air-dried chicken.

Nuclear magnetic resonance study on wettability of shale oil reservoir

In order to identify and evaluate reservoir wettability, so as to select suitable mining methods to improve oil recovery, wettability evaluation through one-dimensional (1D) and two-dimensional (2D) nuclear magnetic resonance (NMR) technology combined with physical simulation experiments was carried out in this study, and the feasibility of the experimental method was verified by contact Angle method. According to the principle of hydrophilic inorganic content and hydrophobic organic content of shale, the wettability can be evaluated through vacuum self-imbibition oil and self-imbibition water physical simulation experiments combined with 1D NMR technology, that is, total water absorption can be considered as inorganic content, organic content can be obtained by subtracting total water absorption from total oil absorption, and adsorbed oil content can be obtained by subtracting pore volume from total oil absorption. In addition to the wettability measurement by contact Angle method to verify the experimental method, the occurrence ratio of adsorbed oil can also be verified twice by 2D NMR spectrum. The results show that the error between the proportion of adsorbed oil measured by 2D NMR spectrum and that measured by self-imbibition method is within 4%. In the saturated oil-bound water state, the bound water is within the relaxation interval of 1&amp;lt;T1&amp;lt;10 ms and 1&amp;lt;T2&amp;lt;10 ms, and the oil signal is within the relaxation interval of T1&amp;gt;10 ms and T2&amp;gt;10 ms. And the relaxation time of aqueous phase moved to the right compared with that in the saturated water state, the interaction force between water and the pore wall was weakened, showing the characteristics of free fluid, and the rock sample became oil-wet, which was consistent with the wettability results measured by contact Angle. Therefore, the wettability of rock samples can be evaluated by 1D NMR technique combined with vacuum imbibition method, or by analyzing the changes of NMR spectra of aqueous phase in completely saturated water and saturated oil-bound water.

Thermodynamics of Swelling of Poly(NIPAM‐co‐NTBA‐co‐HEAAm) Hydrogels

AbstractIn the present study, poly(N‐Isopropylacrylacrylamide‐co‐N‐tertiarybutylacrylamide‐co‐hydroxyethylcrylamide) (NIPAM‐co‐NTBA‐co‐HEAAm) hydrogels are prepared with variation of molar ratio of hydrophilic HEAAm and hydrophobic NTBA. The prepared hydrogels are characterized with elemental analysis and Fourier transform infrared (FTIR) spectroscopy. The thermodynamics of swelling properties of poly(NIPAM‐co‐NTBA‐co‐HEAAm) hydrogels have also been discussed. The experimental C/N ratios are comparable with the theoretical value. The enthalpy change of mixing ∆Hmix, entropy change of mixing ∆Smix, free energy change of mixing ∆Gmix are determined for swelling of hydrogels at 25 °C. The value of total free energy of hydrogel swelling is found to be negative which confirms the lower critical solution temperature (LCST) exhibited in all hydrogels and the volume change transition shows the thermoresponsive behavior. The values of ∆Smix increase and ∆Gmix decrease with increasing amount of hydrophobic NTBA content in the hydrogels. The values of free energy change of elasticity (∆Gel) are found to be increased with increasing the hydrophobic NTBA content followed by decrease in swelling percentage. Also, the transition temperature of the hydrogel is found to be decreased with increasing the hydrophobic NTBA.

Structural Basis for p19 Targeting by Anti–IL-23 Biologics: Correlations with Short- and Long-Term Efficacy in Psoriasis

IL-23 is central to psoriasis pathogenesis. Biologics targeting IL-23 are important therapies against psoriasis. IL-23 inhibitors risankizumab, tildrakizumab, and guselkumab bind the IL-23 p19 subunit, whereas ustekinumab binds p40; however, the structural composition of the IL-23-binding epitopes and how these molecular properties relate to clinical efficacy are not known. Utilizing epitope data derived from hydrogen-deuterium exchange or crystallographic experiments, we mapped inhibitor epitope locations, hydrophobicity, and surface charge onto the IL-23 surface. Molecular properties of each inhibitor epitope, including solvent-accessible surface area, were correlated to binding affinity, kinetic values, and clinical efficacy scores for plaque psoriasis through linear regression analysis. Each IL-23 inhibitor binds an epitope with a unique size, composition, and location except for a 10-residue overlap region outside of the IL-23 receptor epitope. We observed strong correlations between epitope surface area and KD and koff but not kon. Epitope surface area, KD, and koff were further associated with short-term (10-16 weeks) and long-term (44-60 weeks) clinical efficacy according to PASI-90 responses, with risankizumab demonstrating highest efficacy among IL-23 biologics. In contrast, kon, epitope hydrophobicity, polarity, and charge content did not correlate with efficacy. These data exemplify how molecular principles of medications within a therapeutic class can explain their differential clinical responses.

Effect of ultrasound treatment on porcine myofibrillar protein binding furan flavor compounds at different salt concentrations

The effects of ultrasound (500 W) on the interaction of porcine myofibrillar protein (MP) with furan flavor compounds at different salt concentrations (0.6 %, 1.2 % and 2.4 %) were investigated. With the increase of salt concentration, the particle size of MP decreased, and the surface hydrophobicity and active sulfhydryl content increased due to the unfolding and depolymerization of MP. At the same time, ultrasound promoted the exposure of hydrophobic binding sites and hydrogen bonding sites of MP in different salt concentration systems, thus improving the binding ability of MP with furan compounds by 2 % to 22 %, among which MP had the strongest binding capacity of 2-pentylfuran. In conclusion, ultrasound could effectively promote the unfolding of the secondary structure of MP, which was beneficial to the combination of MP and furan flavor compounds under different salt concentrations.

Development of Yellow Discoloration in Sawai (Pangasianodon hypophthalmus) Muscle due to Lipid Oxidation.

In this study, we investigated the impact of lipid oxidation on the discoloration of Sawai (Pangasianodon hypophthalmus) lipids and proteins. Sawai microsomes, liposomes, and salt-soluble myofibrillar proteins were prepared and subjected to lipid oxidation process. The results revealed that the levels of thiobarbituric acid-reactive substances, yellowness (as indicated by b* values), and pyrrole compounds increased when Sawai liposomes and microsomes were oxidized using iron and ascorbate. Meanwhile, the levels of free amines decreased, particularly as the iron content (25∼100 μM) and incubation time (0∼20 h) increased. The impact of oxidized liposomes at different levels (1, 2, and 5%) on the salt-soluble Sawai myofibrillar proteins was also evaluated. The findings revealed that lipid oxidation products reduced the sulfhydryl content and increased the surface hydrophobicity and carbonyl content of the salt-soluble Sawai myofibrillar proteins. These results imply that the formation of yellow discoloration in Sawai muscle could be due to nonenzymatic browning reactions occurring between lipid oxidation products and amines in the muscle protein.

The Design of a Participatory Peptide Nucleic Acid Duplex Crosslinker to Enhance the Stiffness of Self-Assembled Peptide Gels.

Herein, peptide nucleic acids (PNAs) are employed in the design of a participatory duplex PNA-peptide crosslinking agent. Biophysical and mechanical studies show that crosslinkers present during peptide assembly leading to hydrogelation participate in the formation of fibrils while simultaneously installing crosslinks into the higher-order network that constitutes the peptide gel. The addition of 2 mol % crosslinker into the assembling system results in a ~100 % increase in mechanical stiffness without affecting the rate of peptide assembly or the local morphology of fibrils within the gel network. Stiffness enhancement is realized by only affecting change in the elastic component of the viscoelastic gel. A synthesis of the PNA-peptide duplex crosslinkers is provided that allows facile variation in peptide composition and addresses the notorious hydrophobic content of PNAs. This crosslinking system represents a new tool for modulating the mechanical properties of peptide-based hydrogels.

The Design of a Participatory Peptide Nucleic Acid Duplex Crosslinker to Enhance the Stiffness of Self‐Assembled Peptide Gels

AbstractHerein, peptide nucleic acids (PNAs) are employed in the design of a participatory duplex PNA‐peptide crosslinking agent. Biophysical and mechanical studies show that crosslinkers present during peptide assembly leading to hydrogelation participate in the formation of fibrils while simultaneously installing crosslinks into the higher‐order network that constitutes the peptide gel. The addition of 2 mol % crosslinker into the assembling system results in a ~100 % increase in mechanical stiffness without affecting the rate of peptide assembly or the local morphology of fibrils within the gel network. Stiffness enhancement is realized by only affecting change in the elastic component of the viscoelastic gel. A synthesis of the PNA‐peptide duplex crosslinkers is provided that allows facile variation in peptide composition and addresses the notorious hydrophobic content of PNAs. This crosslinking system represents a new tool for modulating the mechanical properties of peptide‐based hydrogels.

Optimizing Excipient Properties to Prevent Aggregation in Biopharmaceutical Formulations.

Excipients are included within protein biotherapeutic solution formulations to improve colloidal and conformational stability but are generally not designed for the specific purpose of preventing aggregation and improving cryoprotection in solution. In this work, we have explored the relationship between the structure and antiaggregation activity of excipients by utilizing coarse-grained molecular dynamics modeling of protein-excipient interaction. We have studied human serum albumin as a model protein, and we report the interaction of 41 excipients (polysorbates, fatty alcohol ethoxylates, fatty acid ethoxylates, phospholipids, glucosides, amino acids, and others) in terms of the reduction of solvent accessible surface area of aggregation-prone regions, proposed as a mechanism of aggregation prevention. Polyoxyethylene sorbitan had the greatest degree of interaction with aggregation-prone regions, decreasing the solvent accessible surface area of APRs by 20.7 nm2 (40.1%). Physicochemical descriptors generated by Mordred are employed to probe the structure-property relationship using partial least-squares regression. A leave-one-out cross-validated model had a root-mean-square error of prediction of 4.1 nm2 and a mean relative error of prediction of 0.077. Generally, longer molecules with a large number of alcohol-terminated PEG units tended to interact more, with qualitatively different protein interactions, wrapping around the protein. Shorter or less ethoxylated compounds tend to form hemimicellar clusters at the protein surface. We propose that an improved design would feature many short chains of 5 to 10 PEG units in many distinct branches and at least some hydrophobic content in the form of medium-length or greater aliphatic chains (i.e., six or more carbon atoms). The combination of molecular dynamics simulation and quantitative modeling is an important first step in an all-purpose protein-independent model for the computer-aided design of stabilizing excipients.

Mechanistic insights into the improving effects of germination on physicochemical properties and antioxidant activity of protein isolate derived from black and white sesame.

Germination is a natural green technology to improve the nutritional and techno-functional quality of plant-based proteins. In this study, the mechanism of improving the functional and antioxidant properties of black and white sesame protein isolates (SPI) through germination process was investigated. Results showed that the surface hydrophobicity and sulfhydryl content increased significantly after germination, which were supported by multispectral analysis suggesting the exposed and unfolded conformational transition of germinated SPI. Moreover, the increased particle size was observed by microscopy analysis and reducing electrophoresis, which indicated that depolymerized protein molecules were rearranged to form protein aggregates during germination. The structural modification induced by germination contributed to the superior solubility (increased to 3.15-fold and 2.36-fold at pH 8 for black and white SPI, respectively), foaming capacity (increased to 3.99-fold and 1.69-fold, respectively), emulsifying ability (increased to 2.84-fold and 2.71-fold, respectively), and diverse chemical antioxidant activities (increased up to 5.60-fold) of SPI in both varieties. This was the first comprehensive study to investigate germination as a promising technology for obtaining high-quality SPI.