Protein Surface Hydrophobicity Research Articles

The impact of ultrasound treatment combined with flaxseed gum on the foaming properties of egg white

The foaming property of egg white (EW) is essential in food processing. In this study, we investigated the effect of ultrasound combined with adding different concentrations (0, 0.4, 0.5, 0.6, 0.7, and 0.8 %, m/v) of flaxseed gum (FG) on EW foaming. The results showed that the cooperation of ultrasound treatment and FG significantly improved the foaming stability. Regarding details, FG reduced the sulfhydryl content and surface hydrophobicity of EW proteins while increasing the average particle size and PDI value. Despite the ultrasound treatment, FG significantly improved the foaming stability from 62.83% to 99.82% (p < 0.05). Based on the analysis of ξ-potential, surface tension, rheology, etc., FG improved the EW microenvironment, which is conducive to foaming stability. As a new type of polysaccharide, FG combined with ultrasound can significantly improve the foaming properties. This research could solve the problem of reduced foaming stability of EW treated by ultrasound alone, making promising applications in the food industry.

Physico-chemical, functional, and structural properties of un-defatted, cold and hot defatted yellow lupin protein isolates

This study investigates the structure, physico-chemical and functional properties of yellow lupin isolate protein (YLPI) obtained by different processes (conventional wet and purely aqueous fractionation) from un-defatted (YLPIU), and hot (YLPIHD) and cold (YLPICD) defatted flour. The defatting process modified the physical, structural and functional characteristics of lupin protein isolates. Indeed, a decrease of α-helix, free sulfhydryl groups amount and an increase of disulfide bond levels were observed for defatted samples, improving their emulsifying stability. The defatting process exposes the hydrophobic groups present within the YLPI, which increases total sulfhydryl content and protein surface hydrophobicity. Hot and cold defatting induced a decrease in turbidity, water-holding capacity, oil adsorption capacity, tapped and poured bulk densities. In addition, the defatting process changed the particle size of protein isolates that induced changes in their viscosity. Tryptophan spectra and protein surface hydrophobicity indicated that YLPICD and YLPIHD underwent structural conformational change during the defatting process.

Nitrogen regulates the synthesis of hydrophobic amino acids to improve protein structural and gel properties in common buckwheat

Nitrogen (N) fertilizer impacts the grain quality of common buckwheat, but the effects and regulatory mechanisms of N on various protein parameters of buckwheat are not fully understood. The purpose of this study was to investigate the particle morphology, structural and gel properties, and regulation mechanism of buckwheat protein under four N levels. The bulk density, surface hydrophobicity, particle size, and thermal properties of the buckwheat protein were maximized through the optimal N application (180 kg N/ha), further enhancing the thermal stability of the protein. N application increased the β-sheet content and reduced the random coil content. Appropriate N fertilizer input enhanced the tertiary structure stability and gel elasticity of buckwheat protein by promoting hydrophobic interactions, disulfide bonds, ionic bonds, storage modulus and loss modulus. The differentially expressed proteins induced by N are primarily enriched in small ribosomal subunit and ribosome, improving protein quality mainly by promoting the synthesis of hydrophobic amino acids. Future agriculture should pay attention to the hydrophobic amino acid content of buckwheat to effectively improve protein quality. This study further advances the application of buckwheat protein in the field of food processing and provides a theoretical basis for the extensive development and utilization of buckwheat protein.

Effects of microwave processing in comparison to sous vide cooking on meat quality, protein structural changes, and in vitro digestibility

This study investigated the effect of industrial microwave (MW) processing, and sous vide (SV) on goat and lamb biceps femoris, where samples were cooked to the same tenderness. The cooked meat quality and ultrastructure were analyzed along with determining the protein surface hydrophobicity, particle size distribution, secondary structure, and protein digestibility. MW-processing resulted in higher cooking loss and more ultrastructural damage than SV and also induced higher myofibrillar protein surface hydrophobicity. Both processes caused a significant increase (p < 0.05) in the β-sheet and an increase in the random coils with a reduction (p < 0.05) in α-helix and β-turns. Both processes led to different protein hydrolysis patterns (observed through SDS-PAGE), but overall free amino N release after digestion was not significantly different among them. The results suggest that MW and SV modify meat protein structure differently, but with the same meat tenderness level, these processes can lead to similar overall protein digestibility.

Combination of pH-shifting, ultrasound, and heat treatments to enhance solubility and emulsifying stability of rice protein isolate

Rice protein isolates (RPI) are promising plant-protein sources but present low solubility and poor surface activity in neutral conditions. Improving these characteristics is a crucial challenge to capitalize on them. This is the first work performing pH-shifting, ultrasound, and heat treatments on a commercial RPI. The combined approaches increased the protein solubility (from ∼2.7% to ∼91.8%) and surface hydrophobicity (up to ∼283%) and induced the formation of less compact and more dispersed protein aggregates. The pH-shifting induced the unfolding of protein molecules and aggregates making them available for modification by both ultrasound and heating, which are supposed to induce further protein unfolding, exposure of buried hydrophobic amino acid, and protein hydrolysis. Also, the combined approaches generated modified RPI able to form oil-in-water emulsions with reduced particle size and enhanced stability than the untreated RPI. Therefore, this work presents an effective combined approach to enhance the techno-functional properties of rice proteins.

Improving the functionality of pea protein with laccase-catalyzed crosslinking mediated by chlorogenic acid

The influences of laccase-catalyzed crosslinking on the structural, emulsifying and gelling properties of pea protein with chlorogenic acid were intensively probed. Molecular weight analysis illustrated the formation of pea protein aggregates by laccase-induced polymerization in the presence of chlorogenic acid and the increase of incubation time facilitated the aggregation. Particle size of pea protein-laccase-chlorogenic acid progressively enhanced increasing incubation time. Laccase-induced polymerization possessed remarkable impacts on the secondary and tertiary structure of pea protein, confirmed by circular dichroism, and fluorescence spectroscopy. Surface hydrophobicity of pea protein appreciably enhanced with laccase-induced crosslinking due to the exposure of interior hydrophobic amino acid residues. Emulsifying activity, emulsifying capacity, gel strength, and water-holding capacity of pea protein can be considerably enhanced with laccase-catalyzed crosslinking with chlorogenic acid, suggesting excellent functionalities for pea protein were accomplished after being modified by laccase with chlorogenic acid. The obtained information will widen pea protein’s application in food systems.

Physiochemical characteristics, morphology, and lubricating properties of size-specific whey protein particles by acid or ion aggregation

To investigate the influence of particle characteristics on their lubricating capacity, microparticles of controlled size (~300, ~700, and ~1900 nm) were prepared from whey proteins using two different approaches: reducing the pH and increasing the calcium ion concentration. The physiochemical, morphological, and tribological properties of the two types of particles were determined. Both treatments pronouncedly decreased the absolute value of zeta-potential and surface hydrophobicity of whey proteins, with calcium ions showing a more severe effect on zeta-potential. The viscosity of the particle suspensions increased with particle size, and ion-induced samples showed higher viscosity than acid-induced ones. Morphology investigation revealed that particle aggregation and irregularity increased with particle size increase. Distinct lubricating behaviors were observed for the two particle types within different size ranges. Viscosity played a more important role in lubrication when the particle size was small, while particle characteristics became more dominant for large particles.

Enhancing the dispersibility of commercial pea protein ingredients using stirred media milling: Potential mechanisms of action

This study found that stirred media milling (SMM) showed great potential in enhancing the functional properties of commercial legume proteins. The effects of SMM on protein dispersibility and structure in 5% pea protein solutions were investigated. The milling increased pea protein dispersibility index from around 12 to 99%, over an 8-fold increase. During milling, the D[4,3] of protein particles decreased from around 122 μm to 320 nm and the magnitude of the zeta potential increased from 21.6 to 30.0 mV. Microscopy analysis revealed that the morphology of the protein particle changed from aggregated, irregular, and dense before milling to uniformly distributed and spherical after milling. And hydrophobic interactions were the primary intramolecular forces maintaining the structure of the water-dispersible protein particles. Intrinsic fluorescence intensity, surface hydrophobicity, and free sulfhydryl group analysis of the pea proteins increased after milling, and there was a net change in the secondary structure of the proteins from β-sheet and random coil to α-helix and β-turn. SDS-PAGE analysis revealed that insoluble protein aggregates transformed into water-dispersible ones after milling. These results suggested that the conformation and aggregate state of protein molecules were changed during milling. This study indicates that the stirred media milling is a simple and effective means of enhancing pea protein dispersibility, which could expand the application of plant protein in the food industry.

Characterization and techno-functional properties of Tenebrio molitor larvae protein concentrate

Global population growth and an alarming rate of global warming conditions have driven the need for protein from alternative non-conventional sources, namely, insect proteins, through a sustainable approach. The protein concentrate of Tenebrio molitor larvae was examined for its suitability and applicability as a food ingredient. Protein was extracted through the acid-alkali method with ∼79% of extraction efficiency. The protein-bound polyphenols were extracted and quantified, and the anti-oxidant potential of protein-bound polyphenols and protein concentrate was assessed. The colour parameters of protein concentrate showed brighter colour (L*, 57.3) than the whole insect powder (L*, 39.0). The surface hydrophobicity of protein concentrate increased to 650, and an increase in the total and free sulfhydryl content (15.39 and 9.158 μmol/g, respectively) was also observed compared to the whole insect powder. Significantly higher protein solubility was observed at pH 2 (72.3%) and pH 11 (66.4%), as compared to near the pI (6.9% at pH 5 and 30.15% at pH 4). Several prominent proteins, including 86 and 56 kDa early-staged encapsulation-inducing proteins, cuticle proteins, and structural proteins were identified in protein concentrate. The techno-functional properties revealed that mealworm protein concentrate was superior to whole insect powder and comparable to whey protein isolate. These findings confirmed the excellent functional properties of mealworm protein concentrate, which can be further explored as a novel food ingredient.

A new approach to enhance quinoa protein nano-aggregates: Combined pH shifting - High pressure homogenization.

The physicochemical characteristics of soluble nano-sized quinoa protein isolates prepared by combined pH shifting and high-pressure homogenization were studied. Commercial quinoa protein isolates were exposed to pH shifting at acidic (pH 2-6) or alkaline (pH 8-12) conditions followed by high-pressure homogenization earlier than neutralizing of pH to 7.0. The pH method under pH 12 followed by high-pressure homogenization was found as the most efficient treatment in the reduction of protein aggregate sizes and transparency, improving soluble protein content and surface hydrophobicity. Quinoa protein isolates treated with pH 12 and high-pressure homogenization increased the solubility from 7.85% to 78.97%, creating quinoa protein isolate nanoaggregates with an average size around 54nm. The quinoa isolate aggregates were used to produce oil-in-water nanoemulsions, which demonstrated the good stability for 14 d at 4°C. This new approach might present an effective technique for the modification of functional features of quinoa protein isolates.

Fabrication of emulsion gels based on sonicated grass pea (Lathyrus sativus L.) protein as a delivery system for β-carotene: Kinetic modeling and release behavior

In this study, the release behavior and encapsulation efficiency of β-carotene in emulsion gels fabricated by sonicated grass pea protein isolate (GPPI) under simulated gastrointestinal conditions were investigated. Therefore, the emulsion gels stabilized by sonicated GPPIs (8% w/v) and corn oil (20% volume fraction and containing 0.5% w/w of β-Carotene) were induced by transglutaminase. The emulsion gels prepared by sonicated GPPIs exhibited sustained release of β-carotene. The Ritger-Peppas model best described the release behavior of β-carotene from the emulsion gels, indicating that the predominant release mechanism was non-Fickian diffusion. Sonicated GPPI-based emulsion gels exhibited higher β-carotene encapsulation efficiency (97.75%) and loading capacity, attributed to increased protein surface hydrophobicity, TGase cross-linking between ϵ-(γ-glutamyl) lysine residues, and the formation of smaller protein particles through ultrasonic treatment. Incorporation of β-carotene within emulsion gels was confirmed by FTIR analysis. Emulsion gels prepared using sonicated GPPIs at 75% amplitude demonstrated approximately fivefold improved bioaccessibility and enhanced retention of β-carotene during storage (20 days) compared to emulsion gels prepared using native GPPI. These findings suggest that structural modification of protein and gel structure can significantly affect the bioaccessibility and stability of β-carotene in the product.

Transglutaminase crosslinked fish gelatins for emulsion stabilization: From conventional to Pickering emulsions

Gelatin-stabilized emulsions, including conventional and Pickering emulsions, are gaining popularity. In this study, fish gelatins (FG) were modified with transglutaminase (TG) to prepare gelatin molecules, microgels, and their mixtures. The transition of emulsions from conventional to Pickering was observed as gelatins evolved from molecules to microgels. FG (3%) was cross-linked with TG at 0–30 U/g. FG evolved from gelatin molecules into thermo-irreversible hydrogels as TG increased. Without TG or at a low level of TG (10 U/g), FG mainly existed as gelatin molecules that were liquid at 25 °C. At high levels of TG (20 or 30 U/g), FG crosslinked and developed thermo-irreversible chemical hydrogels that were solid. As the concentration of TG increased, the protein molecular weights, zeta potentials, and surface hydrophobicity were significantly increased. Microfluidization was employed to prepare gelatin microgels. Different states of gelatins were mixed with sunflower oil to prepare conventional emulsions, Pickering emulsions, and mixtures. With increased TG, the emulsion droplets became more homogeneous, and protein networks formed around the oil droplets. Emulsions stabilized with modified FG displayed improved physical stability than those stabilized with unmodified FG. At 10 °C, the emulsions stabilized by a mixture of FG molecules and microgels presented higher physical stability. At 25 °C, Pickering emulsions stabilized by microgels showed improved anti-coalescence. The results of this work could provide valuable references for applying gelatin-stabilized conventional or Pickering emulsions with tunable properties, hence increasing the formulation flexibility of gelatin-based food products.

Insights into Intramuscular Connective Tissue Associated with Wooden Breast Myopathy in Fast-Growing Broiler Chickens.

Wooden breast myopathy (WBM) is a meat abnormality affecting pectoralis majors (PMs) of fast-growing broiler chickens. WBM-affected PMs exhibited varied meat qualities with increasing WBM severity. Normal PMs (NOR), mild WBM-affected PMs (MIL), moderate WBM-affected PMs (MOD), and severe WBM-affected PMs (SEV) were selected as raw materials. The structure and organization of connective tissue and fibrillar collagen were investigated through immersing with sodium hydroxide solution, Masson trichrome staining, and using an electron microscope. The mechanical strength of intramuscular connective tissue was analyzed via the shear force of samples treated with sodium hydroxide solution. The thermal property and secondary structure of connective tissue were analyzed by differential scanning calorimetry and Fourier transform infrared spectroscopy. The obtained connective tissue was dissolved in a sodium hydroxide solution for the evaluation of the physicochemical properties of proteins, including particle size, molecular weight, surface hydrophobicity, and intrinsic fluorescence. In particular, the particle size was measured using a zeta potential instrument. The molecular weight was analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis. The surface hydrophobicity and intrinsic fluorescence were measured by spectroscopy technology. Histologically, macrophage infiltration, myodegeneration and necrosis, regeneration, fibrous connective tissue, and thickened perimysial connective tissue were observed in WBM-affected PMs, especially SEV with fibrosis, including blood vessels. Compared with NOR, WBM led to increased average diameter of the collagen fibrils in perimysial (36.61 nm of NOR to 69.73 nm of SEV) and endomysial (34.19 nm of NOR to 56.93 nm of SEV) layers. A significant increase (p < 0.05) was observed in the mechanical strength (2.05 N to 5.55 N) of fresh PMs and the thermal transition temperature (onset temperature (TO), 61.53 °C to 67.50 °C; maximum transition temperature (TM), 66.46 °C to 70.18 °C; termination temperature (TE), 77.20 °C to 80.88 °C) of connective tissue from NOR to SEV. Cooking decreased the mechanical strength, and MOD samples showed the highest mechanical strength (1.24 N, p < 0.05), followed by SEV (0.96 N), MIL (0.93 N), and NOR (0.72 N). For proteins in connective tissue, random coil (19.64% to 29.61%, p < 0.0001), particle size (p < 0.05), and surface hydrophobicity (p < 0.05) increased with the decrease in the α-helix (14.61% to 11.54%, p < 0.0001), β-sheet (45.71% to 32.80%, p < 0.0001), and intrinsic fluorescence of proteins from NOR to SEV. The molecular weights of intramuscular connective tissue proteins were in the ranges of >270 kDa, 180-270 kDa, 110-180 kDa, 95-100 kDa, and <15 kDa. Taken together, WBM resulted in thickened organization, tightly packed collagen fibrils, increased mechanical strength and thermal temperature, and increased particle size, surface hydrophobicity, and intrinsic fluorescence of proteins in connective tissue, as the WBM severity increased.

Structure and in vitro digestion characteristics of skim goat milk protein during processing: effects of fat separation.

Although nonfat milk has been used worldwide in the industrial dairy process, little is known about the effects of fat separation during the manufacturing process on skim milk's structural and digestive properties. This study investigated the effects of the manufacturing process on the structure and in vitro digestion properties of skim goat milk, particularly emphasizing fat separation. Changes in the surface charge and hydrophobicity of milk proteins caused by fat separation resulted in oxidation and aggregation in the subsequent homogenization, heat and spray-drying processing, which affected its digestibility. Compared with separation by dish separator (DS), skim milk after tubular centrifugal separation (CS) showed a higher initial and final digestibility. The CS samples also had a lower surface hydrophobicity level and higher free sulfhydryl content, ζ-potential, and average particle size (P < 0.05). Goat milk protein after CS was more readily oxidized and aggregated during the subsequent homogenization and heat treatment, as evidenced by the higher carbonyl content and particle size. Centrifugal separation also converted more β-sheets to α-helices, thus promoting the aggregation of oxidized skim milk protein. The skim milk after CS and DS demonstrated different structural and digestive properties. Skim goat milk products after CS were more susceptible to oxidant-induced protein structural changes, resulting in higher protein digestibility. These findings provide insights into the mechanism involved in the control of gastric digestion of skim milk during manufacturing process. © 2023 Society of Chemical Industry.

Effects of ultrasonic treatment on the structural and functional properties of cactus (Opuntia ficus-indica) seed protein

With the steady increase in the consumption of ultra-processed foods, there is growing interest in sustainable diets that include more plant protein. However, little information is available regarding the structural and functional properties of cactus (Opuntia ficus-indica) seed protein (CSP), a by-product of the cactus seed food-processing chain. This study aimed to explore the composition and nutritional value of CSP and reveal the effects of ultrasound treatment on protein quality. Protein chemical structure analysis showed that an appropriate intensity of ultrasound treatment (450 W) could significantly increase protein solubility (96.46 ± 2.07%) and surface hydrophobicity (13.76 ± 0.85 μg), decrease the content of T-SH (50.25 ± 0.79 μmol/g) and free-SH (8.60 ± 0.30 μmol/g), and enhance emulsification characteristics. Circular dichroism analysis further confirmed that the ultrasonic treatment increased the α-helix and random coil content. Amino acid analysis also suggested that ultrasound treatment (450 W) increased the hydrophobic amino acid content. To evaluate the impact of changes in the chemical structure, its digestion behavior was studied. The results showed that ultrasound treatment increased the release rate of free amino acids. Furthermore, nutritional analysis showed that the digestive products of CSP by ultrasound treatment can significantly enhance the intestinal permeability, increase the expression of ZO-1, Occludin and Claudin-1, thus repairing LPS induced intestinal barrier disfunction. Hence, CSP is a functional protein with high value, and ultrasound treatment is recommended. These findings provide new insights into the comprehensive utilization of cactus fruits.

Determining the impact of genotype × environment on oat protein isolate structural and functional characteristics

AbstractBackground and ObjectivesThe effect of genotype × environment (G × E) on oat protein structural characteristics and functionality was studied using three oat genotypes grown in three different environments across the Canadian Prairies.FindingsThe protein content of oat protein isolate (OPI) ranged from 76.9% to 90.2%. All structural characteristics except protein surface hydrophobicity were significantly impacted by G × E, whereas protein surface hydrophobicity strongly depended on the growing environment. SDS‐PAGE and FT‐IR analysis demonstrated that oat protein profile and secondary structure were significantly impacted by genotype rather than environment. Cultivar Summit grown in Alberta had the highest foaming capacity which was significantly higher than Summit grown in the other environments, indicating a strong influence of environment on OPI foaming capacity.ConclusionThe structure‐function properties of OPI extracted from the given cultivars were influenced by G × E however, further studies are needed to evaluate the stability of the tested cultivars over several years.Significance and NoveltyUnderstanding how OPI structure and functional properties are influenced by G × E will allow better utilization of OPI in the food industry by facilitating the development of OPI ingredients with predictable functional properties.

Effect of Microbial Transglutaminase Treatment on the Techno-Functional Properties of Mung Bean Protein Isolate.

The purpose of this study was to investigate the improvement in techno-functional properties of mung bean protein isolate (MBPI) treated with microbial transglutaminase (MTG), including water- and oil-holding capacity, gelling properties, and emulsifying capacity. MBPI dispersions were incubated with MTG (5 U/g of protein substrate) at 45 °C with constant stirring for 4 h (MTM4) or 8 h (MTM8). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed that MTG treatment for different durations increased the amount of high-molecular-weight proteins in MBPI, and most of the cross-linking by MTG was terminated at 8 h. Improved water-holding capacity, gelling properties, emulsifying capacity, and stability were observed after MTG treatment, and decreased protein solubility and surface hydrophobicity were observed. Furthermore, the texture of the heat-induced gels made from MTG-treated MBPI was evaluated using a texture analyzer. MTG treatment increased the hardness, gumminess, chewiness, and adhesiveness of the heat-induced gels. Field-emission scanning electron microscopy demonstrated the enhanced hardness of the gels. This research reveals that MTG-catalyzed cross-linking may adjust the techno-functional properties of MBPI, allowing it to be used as a soy protein alternative in food products, such as plant-based and processed meats.

Tailoring the rheological properties of high protein suspension by thermal-mechanical treatment

The viscoelasticity of concentrated protein suspensions associates closely with the mixing efficiency and cleaning frequency of facility during high-protein food development. This study investigated the effects of thermal-mechanical treatment on the viscoelasticity of milk protein isolate (MPI) suspensions and their underlying mechanisms to develop protein ingredient with low viscoelasticity. MPI suspensions (20%) were treated at 25, 50 and 85 °C for 10–60 min under constant shear (100 s−1), followed by storage at 4 °C. The viscosity (η) of MPI suspension treated at 50 °C and 85 °C was ∼1–10% as those treated at 25 °C. After four days of storage at 4 °C, η showed the least value in 50°C-treated samples compared to those at 25 °C and 85 °C. The η and storage modulus (G’) was decreased with prolonged treatment at 25 and 50 °C, whereas opposite trend was found in 85 °C treated samples. Differential scanning calorimetry found proteins in 50 °C treated samples had smaller enthalpy than those in the control and 25 °C treated samples. Protein surface hydrophobicity was increased slightly from 25 °C to 50 °C, but remarkably in 85 °C treated samples. Ultra-small angle x-ray scattering showed the radius of gyration (Rg) of casein micelle was ∼38 nm at 25 °C and 50 °C treated samples but increased to ∼44 nm 85 °C treated samples with reduced compactness. A new sphere-like structure with Rg of 18 nm was generated in 85 °C treated samples. These findings suggested modulating temperature during thermal-mechanical treatment is essential to alter protein structures and morphology for desirable rheological properties.

Effects of protein and lipid oxidation on the water holding capacity of different parts of bighead carp: Eye, dorsal, belly and tail muscles

The quality of fish can change due to differences in the lipid and protein oxidation rates in different muscles. This study examined vacuum-packed eye muscle (EM), dorsal muscle (DM), belly muscle (BM), and tail muscle (TM) of bighead carp frozen for 180 days. The results reveal that EM had the highest lipid content and the lowest protein content, while DM had the lowest lipid content and the highest protein content. EM also showed the highest values of centrifugal loss and cooking loss, and the correlation analysis showed that these losses were positively correlated with dityrosine content and negatively correlated with conjugated triene content. The content of carbonyl, disulfide bond, and surface hydrophobicity of myofibrillar protein (MP) also increased with time, with DM having the highest values. The microstructure of EM was looser than other muscles. Therefore, DM had the fastest oxidation rate and EM had the lowest water holding capacity.

Abstract 117: Structure Function Analysis Of Guinea Pig And Human Apolipoprotein E To Obtain Insight Into Their Role In Cardiovascular Disease

Apolipoprotein (apo) E3 (299 amino acids) is a major cholesterol transport protein in the plasma and brain of humans, with the isoform apoE4 considered a risk factor for cardiovascular and Alzheimer’s diseases (CVD and AD). The molecular basis underlying the link between apoE4, and CVD/AD is poorly understood. Previous studies have identified the C-terminal domain (CTD) in promoting protein-lipid, protein-protein and protein-amyloid peptide interactions. In the current study, apoE from Cavia porcellu s (guinea pig, GP) was used as a non-transgenic model to further understand the role of apoE4, since it lacks residues 193-197 and 246-252 of apoE4. We hypothesize that apoE4 CTD plays a critical role in lipid binding, protein folding and amyloid peptide interaction. Recombinant wildtype (WT) GP apoE and insertion mutants GP apoE/Ins193- 197/Ins246-252, and apoE4, and the corresponding deletion mutants apoE4/D193-197/D246-252 were generated. Western blot with anti-apoE4 antibody revealed cross reactivity with GP apoE. Circular dichroism spectroscopy of the variants revealed troughs at 208 and 222 nm indicting that they retained the helical structure observed in WT apoE4. WT GP apoE solubilizes lipids more efficiently than apoE4. Similarly, apoE4/D193-197/D246-252 displayed increased, while GP apoE/Ins193- 197/Ins246-252 showed decreased lipid solubilization ability compared to their WT counterparts. Limited proteolysis analysis indicates that GP apoE was the least susceptible to degradation by trypsin compared to apoE3 and apoE4. Fluorescence analysis using the extrinsic fluorophore anilinonaphthalene sulfonic acid suggests that GP apoE possesses a greater protein surface hydrophobicity than apoE3 and apoE4. Future studies will assess the ability of these variants to promote cholesterol efflux and Aβ binding to gain a better understanding of the role apoE4 in CVD and AD.