Enhancement of functional properties, digestive properties, and in vitro digestion product physiological activity of extruded corn gluten meal by enzymatic modification

BACKGROUND

Enzymatic modification is an effective means of improving the functional properties, digestive properties, and in vitro digestion product physiological activity of proteins, thus significantly expanding protein uses in various food applications.

RESULTS

In this study, the addition of chymotrypsin (CT) at pH 9.0 and 11.0 was found to significantly improve the functional properties (solubility, foaming properties, water holding capacity, oil holding capacity, etc.) and digestive properties of extruded corn gluten meal (ECGM). Similar changes were observed when treating ECGM with glutaminase, protein glutaminase, and papain. These changes were likely due to the increase in number of carboxyl groups and the multiple effects of change in protein net charge and conformation caused by enzymatic deamidation. Of note, ECGM deamidated by CT showed the highest degree of deamidation, solubility, and gastrointestinal digestibility at pH 11.0, up to 44.92%, 43.75%, and 82.22%, respectively. In addition, CT-ECGM digestion product exhibited strong antioxidant activity and potential to promote alcohol metabolism in both a static digestion model and dynamic digestion model, even comparable to commercial corn peptides (CCP), while being inexpensive and of low bitterness compared to CCP. Meanwhile, the physiological activity enhanced as the molecular weight of digestion product decreased with the digested component having strongest activity.

CONCLUSION

This study may promote the application of ECGM as a food component in the food industry or even as a substitute for CCP. © 2023 Society of Chemical Industry.

Protein Post-Translational Modifications Based on Proteomics: A Potential Regulatory Role in Animal Science

Genomic studies in animal breeding have provided a wide range of references; however, it is important to note that genes and mRNA alone do not fully capture the complexity of living organisms. Protein post-translational modification, which involves covalent modifications regulated by genetic and environmental factors, serves as a fundamental epigenetic mechanism that modulates protein structure, activity, and function. In this review, we comprehensively summarize various phosphorylation and acylation modifications on metabolic enzymes relevant to energy metabolism in animals, including acetylation, succinylation, crotonylation, β-hydroxybutylation, acetoacetylation, and lactylation. It is worth noting that research on animal energy metabolism and modification regulation lags behind the demands for growth and development in animal breeding compared to human studies. Therefore, this review provides a novel research perspective by exploring unreported types of modifications in livestock based on relevant findings from human or animal models.

Customizing Starch Properties: A Review of Starch Modifications and Their Applications

Starch has been a convenient, economically important polymer with substantial applications in the food and processing industry. However, native starches present restricted applications, which hinder their industrial usage. Therefore, modification of starch is carried out to augment the positive characteristics and eliminate the limitations of the native starches. Modifications of starch can result in generating novel polymers with numerous functional and value-added properties that suit the needs of the industry. Here, we summarize the possible starch modifications in planta and outside the plant system (physical, chemical, and enzymatic) and their corresponding applications. In addition, this review will highlight the implications of each starch property adjustment.

The foaming properties of sweet potato protein hydrolysates produced by Alcalase and Ficin

BACKGROUND

The processing of sweet potatoes generates a waste by-product rich in sweet potato protein (SPP).

OBJECTIVE

In this study, the effects of the concentrations of Alcalase and Ficin, hydrolysis time and pH value on the foaming properties of SPP hydrolysates (SPPHs) determined via gas sparging method were investigated.

RESULTS

The results showed that SPPH prepared by Alcalase exhibited a significantly higher foaming expansion (the highest of 576%) than that of the SPP (462%) but displayed a weaker liquid volume stability compared with SPPH hydrolyzed by Ficin. The molecular weight of SPPH prepared by Alcalase was distributed in 10-30 kDa. A good microbiological quality of the SPPH prepared by Alcalase in pH 13 has been confirmed, and it is suitable for food application with respect to its microbiological safety profile.

CONCLUSIONS

SPPH (pH 13) could be further safely applied in food, especially as a food additive at low concentrations to create a better organic plant-based foaming agent for the food industry. © 2023 Society of Chemical Industry.

Structural, physicochemical, and functional properties of insoluble dietary fiber derived from okara by Viscozyme® L

The endogenous components of okara can affect the extraction and modification of insoluble dietary fiber (IDF). This study was intended to investigate the effect of extraction and purification of IDFs from okara affected by the endogenous components and composite enzyme Viscozyme^® L. After that, the physicochemical, functional, and structural characteristics of IDFs were analyzed. The results showed that with the purification of degreasing, deproteinizing and destarching, Viscozyme^® L can accurately act on the cell wall of okara, leading to the increase in specific surface area of IDF and the formation of honeycomb-like structure. In accordance with the X-ray diffraction and Fourier-transform infrared spectrum investigations, relative crystallinity decreased and certain cellulose components were reallocated and changed into soluble dietary fiber. Moreover, the modified IDF showed improved water-holding capacity (10.73-11.59 g/g), oil-holding capacity (5.37-6.60 g/g), and swelling capacity (8.99-12.37 mL/g), leading to improved adsorption capacities of glucose (maximum: 39.60 mg/g), cholesterol (14.54-33.56 mg/g at pH 7; 10.94-19.37 mg/g at pH 2), and cholate and better cation-exchange capacity. The outcomes demonstrated the potential for the acquired IDFs, particularly the high-purity modified-IDFs T₃ and T₄ , to be exploited as functional fiber components in the food sector. PRACTICAL APPLICATION: This study advances the understanding of the internal mechanism of modified insoluble dietary fiber (IDF) with different purities in okara. The obtained high-purity modified IDF can be employed as a functional fiber raw material in the manufacture of functional foods, and can also be utilized to assist in the treatment of some illnesses due to its well-established in vivo function.

Influence of Arabinan Fine Structure, Galacturonan Backbone Length, and Degree of Esterification on the Emulsifying Properties of Acid-Extracted Sugar Beet Pectins

Sugar beet pectins (SBPs) are known for their emulsifying properties, but it is yet unknown which structural elements are most important for functionality. Recent results indicated that the arabinose content has a decisive influence, but the approach applied did not allow causality to be established. In this study, a mostly intact SBP was selectively modified and the obtained pectins were analyzed for their molecular structure and their emulsifying properties. De-esterification only resulted in a moderate increase in droplet size. The length of the pectin backbone only influenced the emulsifying properties when the homogalacturonan backbone was cleaved to a higher extent. By using different arabinan-modifying enzymes, it was demonstrated that both higher portions and chain lengths of arabinans positively influence the emulsifying properties of SBPs. Therefore, we were able to refine the structure-function relationships for acid-extracted SBPs, which can be used to optimize extraction conditions.

Impact of Cassava Starch Varieties on the Physiochemical Change during Enzymatic Hydrolysis

The enzymatic modification of starch extends its industrial use to flavor delivery and probiotic encapsulants, among other uses. However, it is not known how starch from different cassava varieties responds to enzymatic hydrolysis. Starches from two Ecuadorian cassava varieties (INIAP 650, an edible starch, and INIAP 651, an industrial starch) were partially modified at three enzymatic hydrolysis degrees (0%, 30%, and 50%), and their physicochemical properties were assessed. The structural analysis revealed that both varieties showed progressive structural damage as hydrolysis increases, probably due to exo-hydrolysis. However, deeper pores were observed in INIAP 651 with the SEM analysis. The crystallinity percentage obtained by XRD analyses remained constant in INIAP 651 and decreased (by 26%) in INIAP 650 (p < 0.05). In addition, the amylose−lipid complex index in INIAP 650 remained constant, while INIAP 651 increased (p < 0.05) at 30% hydrolysis (by 93%). In both varieties, hydrolysis increased (p < 0.05) the water holding capacity (WHC) (by 10−14%) and the water binding capacity (WBC) (by 16%), but 50% hydrolysis of INIAP 650 was needed to significantly affect these properties. No differences were observed in the varieties’ thermal properties. Regarding the rheological properties, the variety did not influence the changes in the storage module (G′) and the loss modulus (G″) with the hydrolysis (p > 0.05). However, the phase angle decreased significantly (p < 0.05) with the hydrolysis, being higher in the INIAP 650 variety than in the INIAP 651 variety. In general, the results indicate that the variety affects the response of the starch granule to enzymatic hydrolysis (noticeable in the principal component analysis, PCA) and opens up the possibility to modulate starch properties.

Effect of Physical and Enzymatic Modifications on Composition, Properties and In Vitro Starch Digestibility of Sacred Lotus (Nelumbo nucifera) Seed Flour

In this study, native lotus seed flour (N-LSF) was modified by different methods, namely, partial gelatinization (PG), heat−moisture treatment (HMT), or pullulanase treatment (EP). Their composition, functional properties, starch composition, and estimated glycemic index (eGI) were compared. PG contained similar protein, soluble dietary fiber, and insoluble dietary fiber contents to N-LSF, while those of HMT and EP differed from their native form. PG increased rapid digestible starch (RDS) but decreased resistant starch (RS); while HMT and EP increased amylose and RS contents to 34.57−39.23% and 86.99−92.52% total starch, respectively. Such differences led to the different pasting properties of the modified flours rather than PG, which was comparable to the native flour. HMT had limited pasting properties, while EP gave the highest viscosities upon pasting. The eGI of all samples could be classified as low (<50), except that of PG, which was in the medium range (60). It was plausible that lotus seed flour modified either with HMT or EP could be used as carbohydrate source for diabetes patients or health-conscious people.

Optimization of Corn Resistant Starch Preparation by Dual Enzymatic Modification Using Response Surface Methodology and Its Physicochemical Characterization

Corn starch was dually modified using thermostable α-amylase and pullulanase to prepare resistant starch (RS). The concentration of starch liquid, the amount of added thermostable α-amylase, the duration of enzymatic hydrolysis and the amount of added pullulanase were optimized using RSM to increase RS content of the treated sample. The optimum pretreatment conditions were 15% starch liquid, 3 U/g thermostable α-amylase, 35 min of enzymatic hydrolysis and 8 U/g pullulanase. The maximum RS content of 10.75% was obtained, and this value was significantly higher than that of native corn starch. The degree of polymerization (DP) of the enzyme-modified starch decreased compared with that of native starch. The scanning electron microscopy (SEM) and differential scanning calorimetry (DSC) were performed to assess structural changes in native and pretreated starch. The effect of dual enzyme pretreatment on the structure and properties of corn starch was significant. Unlike the untreated one, the pretreated corn starch showed clear pores and cracks. Significant differences in RS contents and structural characterization between starch pretreated and untreated with dual enzymes demonstrated that the dual enzyme modification of corn was effective in enhancing RS contents.

Biodegradation and Prospect of Polysaccharide from Crustaceans

Marine crustacean waste has not been fully utilized and is a rich source of chitin. Enzymatic degradation has attracted the wide attention of researchers due to its unique biocatalytic ability to protect the environment. Chitosan (CTS) and its derivative chitosan oligosaccharides (COSs) with various biological activities can be obtained by the enzymatic degradation of chitin. Many studies have shown that chitosan and its derivatives, chitosan oligosaccharides (COSs), have beneficial properties, including lipid-lowering, anti-inflammatory and antitumor activities, and have important application value in the medical treatment field, the food industry and agriculture. In this review, we describe the classification, biochemical characteristics and catalytic mechanisms of the major degrading enzymes: chitinases, chitin deacetylases (CDAs) and chitosanases. We also introduced the technology for enzymatic design and modification and proposed the current problems and development trends of enzymatic degradation of chitin polysaccharides. The discussion on the characteristics and catalytic mechanism of chitosan-degrading enzymes will help to develop new types of hydrolases by various biotechnology methods and promote their application in chitosan.

Polycistronic Expression System for Pichia pastoris Composed of Chitino- and Chitosanolytic Enzymes

Chitin is one of the most abundant biopolymers. Due to its recalcitrant nature and insolubility in accessible solvents, it is often considered waste and not a bioresource. The products of chitin modification such as chitosan and chitooligosaccharides are highly sought, but their preparation is a challenging process, typically performed with thermochemical methods that lack specificities and generate hazardous waste. Enzymatic treatment is a promising alternative to these methods, but the preparation of multiple biocatalysts is costly. In this manuscript, we biochemically characterised chitin deacetylases of Mucor circinelloides IBT-83 and utilised one of them for the construction of the first eukaryotic, polycistronic expression system employing self-processing 2A sequences. The three chitin-processing enzymes; chitin deacetylase of M. circinelloides IBT-83, chitinase from Thermomyces lanuginosus, and chitosanase from Aspergillus fumigatus were expressed under the control of the same promoter in methylotrophic yeast Pichia pastoris and characterised for their synergistic action towards their respective substrates.

Study on the Relationship between Emulsion Properties and Interfacial Rheology of Sugar Beet Pectin Modified by Different Enzymes

The contribution of rheological properties and viscoelasticity of the interfacial adsorbed layer to the emulsification mechanism of enzymatic modified sugar beet pectin (SBP) was studied. The component content of each enzymatic modified pectin was lower than that of untreated SBP. Protein and ferulic acid decreased from 5.52% and 1.08% to 0.54% and 0.13%, respectively, resulting in a decrease in thermal stability, apparent viscosity, and molecular weight (Mw). The dynamic interfacial rheological properties showed that the interfacial pressure and modulus (E) decreased significantly with the decrease of functional groups (especially proteins), which also led to the bimodal distribution of particle size. These results indicated that the superior emulsification property of SBP is mainly determined by proteins, followed by ferulic acid, and the existence of other functional groups also promotes the emulsification property of SBP.

Production of Nanocellulose by Enzymatic Treatment for Application in Polymer Composites

In the last few years, the scientific community around the world has devoted a lot of attention to the search for the best methods of obtaining nanocellulose. In this work, nanocellulose was obtained in enzymatic reactions with strictly defined dispersion and structural parameters in order to use it as a filler for polymers. The controlled enzymatic hydrolysis of the polysaccharide was carried out in the presence of cellulolytic enzymes from microscopic fungi-Trichoderma reesei and Aspergillus sp. It has been shown that the efficiency of bioconversion of cellulose material depends on the type of enzymes used. The use of a complex of cellulases obtained from a fungus of the genus Trichoderma turned out to be an effective method of obtaining cellulose of nanometric dimensions with a very low polydispersity. The effect of cellulose enzymatic reactions was assessed using the technique of high-performance liquid chromatography coupled with a refractometric detector, X-ray diffraction, dynamic light scattering and Fourier transform infrared spectroscopy. In the second stage, polypropylene composites with nanometric cellulose were obtained by extrusion and injection. It was found by means of X-ray diffraction, hot stage optical microscopy and differential scanning calorimetry that nanocellulose had a significant effect on the supermolecular structure, nucleation activity and the course of phase transitions of the obtained polymer nanocomposites. Moreover, the obtained nanocomposites are characterized by very good strength properties. This paper describes for the first time that the obtained cellulose nanofillers with defined parameters can be used for the production of polymer composites with a strictly defined polymorphic structure, which in turn may influence future decision making about obtaining materials with controllable properties, e.g., high flexibility, enabling the thermoforming process of packaging.

Modification of pulse proteins for improved functionality and flavor profile: A comprehensive review

Consumers' preference to have a healthy eating pattern has led to an increasing demand for more nutrient-dense and healthier plant-based foods. Pulse proteins are exceptional quality ingredients with potential nutritional benefits, and might act as health-promoting agents for addressing the new-generation foods. However, the utilization of pulse protein in foods has been hampered by its relatively poor functionality and unpleasant flavor. Protein structure modification has been proved to be a useful means to improve the functionality and flavor profile of pulse protein. This paper begins with a brief introduction of hierarchical structure of pulse protein materials to better understand the structure characteristics. A comprehensive review is presented on the current techniques including chemical and enzymatic modifications and molecular breeding on pulse protein structure and functionality/flavor. The mechanism and the limitations and the toxicological concerns of these approaches are discussed. We conclude that understanding protein structure-functionality relationship is extremely valuable in tailoring proteins for specific functional outcomes and expanding the availability of pulse proteins. Furthermore, selective protein modification is a valuable in-depth toolkit for generating novel protein constructs with preferable functional attributes and flavor profiles. Innovative structure modification with special focus on the molecular basis for the exquisite protein designs is a pillar of pulse protein access to the desired functionality.

Feruloylated Arabinoxylan and Oligosaccharides: Chemistry, Nutritional Functions, and Options for Enzymatic Modification

Cereal brans and grain endosperm cell walls are key dietary sources of different types of arabinoxylan. Arabinoxylan is the main group of hemicellulosic polysaccharides that are present in the cell walls of monocot grass crops and hence in cereal grains. The arabinoxylan polysaccharides consist of a backbone of β-(1→4)-linked xylopyranosyl residues, which carry arabinofuranosyl moieties, hence the term arabinoxylan. Moreover, the xylopyranosyl residues can be acetylated or substituted by 4-O-methyl-d-glucuronic acid. The arabinofuranosyls may be esterified with a feruloyl group. Feruloylated arabinoxylo-oligosaccharides exert beneficial bioactivities via prebiotic, immunomodulatory, and/or antioxidant effects. New knowledge on microbial enzymes that catalyze specific structural modifications of arabinoxylans can help us understand how these complex fibers are converted in the gut and provide a foundation for the production of feruloylated arabinoxylo-oligosaccharides from brans or other cereal grain processing sidestreams as functional food ingredients. There is a gap between the structural knowledge, bioactivity data, and enzymology insight. Our goal with this review is to present an overview of the structures and bioactivities of feruloylated arabinoxylo-oligosaccharides and review the enzyme reactions that catalyze specific changes in differentially substituted arabinoxylans.

The Quality of Emulsions with New Synthetized Lipids Stabilized by Xanthan Gum

The study investigated the quality of emulsions containing rabbit fat modified with vegetable oil. The modification of the fat and introducing it as a fatty base into the emulsion was dictated by consumer preferences. Emulsion systems containing various fatty bases and viscosity modifier contents were evaluated in the terms of their stability (by means of Turbiscan test), texture properties, color, and viscosity. Moreover, the emulsions were assessed by a sensory panel in the context of the intensity of the following parameters: color, fragrance, consistency, greasiness, and hydration. The same characteristics were also subject to consumer evaluation. The results of the sensory assessment showed the sensory panel attributed higher scores to consistency and skin hydration to the emulsions formed with modified fats; these systems were more appreciated by consumers as well. The results confirmed a major role of sensory determinations in the development of new emulsion products. They also provide knowledge on modifications to product characteristics that would lead to the best possible quality and consumer acceptance. This research has also reaffirmed that looking for new fats among waste fats is becoming a solution to finding new fatty bases for emulsions. The natural origin of these components, and thus their agreeability with the human body, appear noteworthy as well. Enrichment with unsaturated fatty acids is an added advantage of the enzymatic modification of rabbit fat with pumpkin seed oil and can be applied not only for food but also for skin applications.

Enzymatically Modified Fats Applied in Emulsions Stabilized by Polysaccharides

The subject of the study was emulsions based on enzymatically modified fats and stabilized with polysaccharides (xanthan gum and scleroglucan). Emulsion oil phases (blends of mutton tallow and hemp seed oil in a ratio of 3:1, 3:2, 3:3, 2:3 and 1:3) were characterized in the terms of acid value, melting point and mono- and diacylglycerols content before and after the modification. Emulsions containing modified fat blends and various amount (0.6, 0.8 and 1.0% w/w) of polysaccharides were investigated in the terms of their color, rheological properties, microstructure, droplet size and stability. The obtained results confirmed that enzymatic modification allowed to produce new fats, which can successfully be applied as an emulsion oil phases equipped with a sufficient amount of emulsifiers. The use of a variable amount of texture modifier in the proposed formulations did not show clear differences in the stability of the systems. Therefore, it does not seem justified to use greater amounts of a modifier (above 0.6% w/w) in this type of emulsions. The proposed formulations could be of interest to the cosmetics, food or pharmaceutical industry.

Extraction and Modification of Macroalgal Polysaccharides for Current and Next-Generation Applications

Marine macroalgal (seaweed) polysaccharides are highly promising for next-generation applications in several industries. However, despite the reported comprehensive potential of these polysaccharides, commercial products are scarce on the market. Seaweed cultivations are increasing in number and production quantity, owing to an elevated global trend of utilization interest in seaweed. The extraction of polysaccharides from seaweed generally generates low yields, but novel methods are being developed to facilitate and improve the extraction processes. Current areas of applications for seaweed polysaccharides mainly take advantage of the physicochemical properties of certain polysaccharides, such as gelling, thickening and emulsifying. However, many of the numerous bioactivities reported are still only at research level and lack clinical evidence for commercialization. It has been suggested the construction of smaller units may generate better defined molecules that are more suitable for biomedical applications. Enzymatic modification is a promising tool for the generation of more defined, targeted biomolecules. This review covers; structural differences between the most predominant marine algal polysaccharides, extraction processes, modification alternatives, as well as a summary of current and potential next-generation application areas.

Enzymatic Modification of Native Chitin and Conversion to Specialty Chemical Products

Chitin is one of the most abundant biomolecules on earth, occurring in crustacean shells and cell walls of fungi. While the polysaccharide is threatening to pollute coastal ecosystems in the form of accumulating shell-waste, it has the potential to be converted into highly profitable derivatives with applications in medicine, biotechnology, and wastewater treatment, among others. Traditionally this is still mostly done by the employment of aggressive chemicals, yielding low quality while producing toxic by-products. In the last decades, the enzymatic conversion of chitin has been on the rise, albeit still not on the same level of cost-effectiveness compared to the traditional methods due to its multi-step character. Another severe drawback of the biotechnological approach is the highly ordered structure of chitin, which renders it nigh impossible for most glycosidic hydrolases to act upon. So far, only the Auxiliary Activity 10 family (AA10), including lytic polysaccharide monooxygenases (LPMOs), is known to hydrolyse native recalcitrant chitin, which spares the expensive first step of chemical or mechanical pre-treatment to enlarge the substrate surface. The main advantages of enzymatic conversion of chitin over conventional chemical methods are the biocompability and, more strikingly, the higher product specificity, product quality, and yield of the process. Products with a higher M_w due to no unspecific depolymerisation besides an exactly defined degree and pattern of acetylation can be yielded. This provides a new toolset of thousands of new chitin and chitosan derivatives, as the physio-chemical properties can be modified according to the desired application. This review aims to provide an overview of the biotechnological tools currently at hand, as well as challenges and crucial steps to achieve the long-term goal of enzymatic conversion of native chitin into specialty chemical products.

Silk/Natural Rubber (NR) and 3,4-Dihydroxyphenylalanine (DOPA)-Modified Silk/NR Composites: Synthesis, Secondary Structure, and Mechanical Properties

Silk composites with natural rubber (NR) were prepared by mixing degummed silk and NR latex solutions. A significant enhancement of the mechanical properties was confirmed for silk/NR composites compared to a NR-only product, indicating that silk can be applied as an effective reinforcement for rubber materials. Attenuated total reflection Fourier transform infrared (ATR-FTIR) and wide-angle X-ray diffraction (WAXD) analysis revealed that a β-sheet structure was formed in the NR matrix by increasing the silk content above 20 wt%. Then, 3,4-dihydroxyphenylalanine (DOPA)-modified silk was also blended with NR to give a DOPA-silk/NR composite, which showed superior mechanical properties to those of the unmodified silk-based composite. Not only the chemical structure but also the dominant secondary structure of silk in the composite was changed after DOPA modification. It was concluded that both the efficient adhesion property of DOPA residue and the secondary structure change improved the compatibility of silk and NR, resulting in the enhanced mechanical properties of the formed composite. The knowledge obtained herein should contribute to the development of the fabrication of novel silk-based elastic materials.

Strategic labelling approaches for RNA single-molecule spectroscopy

Most single-molecule techniques observing RNA in vitro or in vivo require fluorescent labels that have to be connected to the RNA of interest. In recent years, a plethora of methods has been developed to achieve site-specific labelling, in many cases under near-native conditions. Here, we review chemical as well as enzymatic labelling methods that are compatible with single-molecule fluorescence spectroscopy or microscopy and show how these can be combined to offer a large variety of options to site-specifically place one or more labels in an RNA of interest. By either chemically forming a covalent bond or non-covalent hybridization, these techniques are prerequisites to perform state-of-the-art single-molecule experiments.

Covalent Whey Protein-Rosmarinic Acid Interactions: A Comparison of Alkaline and Enzymatic Modifications on Physicochemical, Antioxidative, and Antibacterial Properties

The covalent interactions between whey protein isolate (WPI) and rosmarinic acid (RosA) at two different conditions, alkaline (pH 9) and enzymatic (in the presence of tyrosinase, PPO), at room temperature with free atmospheric air were studied. The conjugates formed between WPI and RosA were characterized in terms of their physicochemical and functional properties. The changes in protein structure were analyzed by intrinsic fluorescence and binding of 8-anilino-1-naphthalenesulfonic acid. The findings show that the covalent interactions caused a decrease in free amino and thiol groups and tryptophan content at both conditions. The decrease at enzymatic conditions was lower than at alkaline conditions. In addition, modified WPI at alkaline conditions exhibited higher antioxidative capacity compared to the modification at enzymatic conditions. However, WPI modified at enzymatic condition showed mild antimicrobial activity against Staphylococcus aureus LMG 10147 and MU50 compared to WPI modified at alkaline conditions and unmodified WPI (control). The modified WPI can be used as multifunctional ingredient into various food products with an additional health promoting effect of the bound phenolic compounds.

Enzymatic Modification of Rice Bran Polysaccharides by Enzymes from Grifola Frondosa: Natural Killer Cell Cytotoxicity and Antioxidant Activity

Rice bran polysaccharides (RBPSs) are the major active constituents of rice bran (RB). In this study, we utilized intracellular enzymes from Grifola frondosa to modify RBPSs, which were extracted from RB using ultrasound. To enhance the effect on natural killer (NK) cell cytotoxicity of modified polysaccharides (mRBPSs) generated from RBPSs, an orthogonal test (L₉ [3]⁴ ) was employed to optimize the modification conditions. Based on the results of a single-factor test, the enzyme to polysaccharide ratio, reaction temperature, reaction pH, and reaction time were the main factors affecting mRBPSs-enhanced NK-cell cytotoxicity. The best conditions were determined to be an enzyme to polysaccharide ratio of 1:5, a reaction temperature of 40 °C, a reaction pH of 4, and a reaction time of 4 hr. By optimizing the conditions, the NK-cell cytotoxicity induced by mRBPSs₆ was the highest, increasing by 12.01% ± 0.08%. Gas chromatographic analysis revealed that mRBPSs₆ consists of rhamnose, arabinose, xylose, mannose, glucose, and galactose at a molar ratio of 7:21:6:5:53:48, which was 8:13:8:5:44:44 before modification. High-performance liquid chromatography results indicated molecular weights for the RBPSs of approximately 10⁶ Da, which decreased to 10⁴ to 10⁵ Da after modification. Antioxidant activity tests revealed high capacity of mRBPSs₆ for scavenging 1,1-diphenyl-2-picrylhydrazyl radicals and hydroxyl free radicals at 1.0 mg/mL.

PRACTICAL APPLICATION

Rice bran polysaccharides (RBPSs) contain compounds with many biological activities. However, these polysaccharides difficult to absorb due to high molecular weights and unexposed active sites, which are the main factors that limit their use in functional foods. The results of this study demonstrate that modification of RBPSs using intracellular enzymes from an edible fungus alters the molecular weights and monosaccharide composition of RBPSs. In addition, immune and antioxidant activities of RBPSs were increased. The findings provide a new and beneficial application for rice bran.

Epigenetic Regulation of the Biosynthesis & Enzymatic Modification of Heparan Sulfate Proteoglycans: Implications for Tumorigenesis and Cancer Biomarkers

Emerging evidence suggests that the enzymes in the biosynthetic pathway for the synthesis of heparan sulfate moieties of heparan sulfate proteoglycans (HSPGs) are epigenetically regulated at many levels. As the exact composition of the heparan sulfate portion of the resulting HSPG molecules is critical to the broad spectrum of biological processes involved in oncogenesis, the epigenetic regulation of heparan sulfate biosynthesis has far-reaching effects on many cellular activities related to cancer progression. Given the current focus on developing new anti-cancer therapeutics focused on epigenetic targets, it is important to understand the effects that these emerging therapeutics may have on the synthesis of HSPGs as alterations in HSPG composition may have profound and unanticipated effects. As an introduction, this review will briefly summarize the variety of important roles which HSPGs play in a wide-spectrum of cancer-related cellular and physiological functions and then describe the biosynthesis of the heparan sulfate chains of HSPGs, including how alterations observed in cancer cells serve as potential biomarkers. This review will then focus on detailing the multiple levels of epigenetic regulation of the enzymes in the heparan sulfate synthesis pathway with a particular focus on regulation by miRNA and effects of epigenetic therapies on HSPGs. We will also explore the use of lectins to detect differences in heparan sulfate composition and preview their potential diagnostic and prognostic use in the clinic.

Enzymatic Modification of Corn Starch Influences Human Fecal Fermentation Profiles

Enzymatically modified starches have been widely used in food applications to develop new products, but information regarding digestion and fecal fermentation of these products is sparse. The objective of this study was to determine the fermentation properties of corn starch modified with α-amylase, amyloglucosidase, or cyclodextrin glycosyltransferase and the possible role of hydrolysis products. Samples differed in their digestibility and availability to be fermented by the microbiota, resulting in differences in microbial metabolites produced during in vitro fermentation. The presence or absence of hydrolysis products and gelatinization affected starch composition and subsequent metabolite production by the microbiota. Amyloglucosidase-treated starch led to the greatest production of short- and branched-chain fatty acid production by the microbiota. Results from this study could be taken into consideration to confirm the possible nutritional claims and potential health benefits of these starches as raw ingredients for food development.

Enzymatic Modification of Soluble Cyanophycin Using the Type II Peptidyl Arginine Deiminase from Oryctolagus cuniculus

An increased structural variety expands the number of putative applications for cyanophycin (multi-l-arginyl-poly-[l-aspartic acid], CGP). Therefore, structural modifications of CGP are of major interest; these are commonly obtained by modification and optimization of the bacterial producing strain or by chemical modification. In this study, an enzymatic modification of arginine side chains from lysine-rich CGP is demonstrated using the peptidyl arginine deiminase from Oryctolagus cuniculus, purified from Escherichia coli after heterologous expression. About 10% of the arginine side chains are converted to citrulline which corresponds to 4% of the polymer's total side chains. An inhibition of the reaction in the presence of small amounts of l-citrulline is observed, thereby explaining the low conversion rate. CGP dipeptides can be modified with about 7.5 mol% of the Asp-Arg dipeptides being converted to Asp-Cit. These results show that the enzymatic modification of CGP is feasible, opening up a whole new area of possible CGP modifications for further research.

Site-Specific PEGylation of Therapeutic Proteins

The use of proteins as therapeutics has a long history and is becoming ever more common in modern medicine. While the number of protein-based drugs is growing every year, significant problems still remain with their use. Among these problems are rapid degradation and excretion from patients, thus requiring frequent dosing, which in turn increases the chances for an immunological response as well as increasing the cost of therapy. One of the main strategies to alleviate these problems is to link a polyethylene glycol (PEG) group to the protein of interest. This process, called PEGylation, has grown dramatically in recent years resulting in several approved drugs. Installing a single PEG chain at a defined site in a protein is challenging. Recently, there is has been considerable research into various methods for the site-specific PEGylation of proteins. This review seeks to summarize that work and provide background and context for how site-specific PEGylation is performed. After introducing the topic of site-specific PEGylation, recent developments using chemical methods are described. That is followed by a more extensive discussion of bioorthogonal reactions and enzymatic labeling.

Toward Overcoming Staphylococcus aureus Aminoglycoside Resistance Mechanisms with a Functionally Designed Neomycin Analogue

Deoxygenation of the diol groups in rings A and D of neomycin in combination with the introduction of an N1-(l)-HABA group in the 2-deoxystreptamine subunit (ring B) leads to a novel and potent antibiotic (1) with activity against strains of S. aureus carrying known aminoglycoside resistance determinants, as well as against an extended panel of Methicillin-resistant S. aureus isolates (n = 50). Antibiotic 1 displayed >64 fold improvement in MIC50 and MIC90 against this MRSA collection when compared to the clinically relevant aminoglycosides amikacin and gentamicin. The synthesis was achieved in six steps and 15% overall yield.