Increased hydrophobicity of carboxymethyl starch film by conjugation with zein

A carboxymethyl starch (CMS) film was prepared by a process in which gelatinized CMS was dried, and subsequently treated with water-soluble carbodiimide in the presence of zein in 70% ethanol or 70% acetone to form acid-amide cross-linkages in order to increase the hydrophobicity of the surface of the film. A small amount of zein protein was found to be present on the surface of the zein-CMS conjugate (Zein-CMS) film, resulting in its insolubility in hot water, low water vapor permeability, and resistance to digestion with alpha-amylase and beta-amylase. Digestion of the Zein-CMS film with protease rendered the film readily water-soluble, suggesting conjugation with zein as an effective means of increasing the hydrophobicity of biodegradable starch-based articles.     

Fabrication of curcumin-loaded zein nanoparticles stabilized by sodium caseinate/sodium alginate: Curcumin solubility,thermal properties,rheology, and stability

Curcumin is a polyphenol with multiple biological activities, but its extremely poor water solubility severely limits its application in the food industry. The purposes of this work were to study the effect of nano-encapsulation on the water solubility of curcumin (C), the interaction of curcumin with zein (Z), the thermal properties, rheological properties, and the stability under different environmental pressures of the nanoparticles. The results of particle size, zeta potential, and surface hydrophobicity (H₀) indicated that the combination of coating materials including sodium caseinate (SC) and sodium alginate (SA) with zein nanoparticles by electrostatic interaction led to a gradual increase in the particle size of composite nanoparticles and a decrease in surface hydrophobicity. The nano-encapsulation significantly improved the water solubility of curcumin and causing its crystal structure to change to an amorphous state. Fourier transform infrared spectroscopy confirmed that curcumin bound to zein through hydrogen bonding. Rheological test results showed that the coating materials combined with zein led to an increase in the apparent viscosity of the nanoparticles. The stability analysis results indicated that the composite nanoparticles with a sodium alginate coating have excellent stability of pH, salt solution and storage, and excellent anti-gastrointestinal fluids digestion characteristics when compared to pure protein nanoparticles.     

Encapsulation of Biologically Active Proteins in a Multiple Emulsion

To improve the stability of IgY antibody in oral administration, encapsulation of IgY in a W/O/W emulsion was attempted. A stable W/O/W emulsion containing 1% IgY was prepared by using polyglyceryl condensed ricinolate (PGCR) and dextran-casein conjugate as the primary and secondary emulsifier, respectively. However, the activity of IgY antibody was reduced to less than 20% by encapsulation, suggesting that denaturation/inactivation of IgY had occurred at the oil/water interface. Adsorption of IgY to the inner water droplet surface was observed by electron microscopy. Rabbit IgG, α-amylase, and lysozyme also lost their activity after being encapsulated, although the rate of inactivation was lower than that of IgY. Molecular characterization of these proteins suggested that the rate of inactivation after encapsulation is likely to be dependent on the surface hydrophobicity and molecular stability of each protein.     

Zein adsorption to hydrophilic and hydrophobic surfaces investigated by surface plasmon resonance

Zein, the prolamine of corn, has been investigated for its potential as an industrial biopolymer. In previous research, zein was plasticized with oleic acid and formed into sheets/films. Physical properties of films were affected by film structure and controlled in turn by zein-oleic acid interactions. The nature of such interactions is not well understood. Thus, protein-fatty acid interactions were investigated in this work by the use of surface plasmon resonance (SPR). Zein adsorption from 75% aqueous 2-propanol solutions, 0.05% to 0.5% w/v, onto hydrophilic and hydrophobic self-assembled monolayers (SAMs) formed by 11-mercaptoundecanoic acid and 1-octanethiol, respectively, was monitored by high time resolution SPR. Initial adsorption rate and ultimate surface coverage increased with bulk protein concentration for both surfaces. The initial slope of plotted adsorption isotherms was higher on 11-mercaptoundecanoic acid than on 1-octanethiol, indicating higher zein affinity for hydrophilic SAMs. Also, maximum adsorption values were higher for zein on hydrophilic than on hydrophobic SAMs. Flushing off loosely bound zein in the SPR cell allowed estimation of apparent monolayer values. Differences in monolayer values for hydrophobic and hydrophilic surfaces were explained in terms of zein adsorption footprint.     

Adsorption of zein on surfaces with controlled wettability and thermal stability of adsorbed zein films

Adsorption characteristics of zein protein on hydrophobic and hydrophilic surfaces have been investigated to understand the orientation changes associated with the protein structure on a surface. The protein is adsorbed by a self-assembly procedure on a monolayer-modified gold surface. It is observed that zein shows higher affinity toward hydrophilic than hydrophobic surfaces on the basis of the initial adsorption rate followed by quartz crystal microbalance studies. Reflection absorption infrared (RAIR) spectroscopic studies reveal the orientation changes associated with the adsorbed zein films. Upon adsorption, the protein is found to be denatured and the transformation of alpha-helix to beta-sheet form is inferred. This transformation is pronounced when the protein is adsorbed on hydrophobic surfaces as compared to hydrophilic surfaces. Electrochemical techniques (cyclic voltammetry and impedance techniques) are very useful in assessing the permeability of zein film. It is observed that the zein moieties adsorbed on hydrophilic surfaces are highly impermeable in nature and act as a barrier for small molecules. The topographical features of the deposits before and after adsorption are analyzed by atomic force microscopy. The protein adsorbed on hydrophilic surface shows rod- and disclike features that are likely to be the base units for the growth of cylindrical structures of zein. The thermal stability of the adsorbed zein film has been followed by variable-temperature RAIR measurements.     

不同壁材微胶囊饲料对黄姑鱼稚鱼生长和消化酶活力的影响

研究采用湿法制粒流化床包衣工艺, 分别以明胶、乙基纤维素、玉米醇溶蛋白为壁材制备微胶囊饲料, 比较其对黄姑鱼稚鱼生长和消化酶活力的影响. 粒径(178-590) m的3种微胶囊饲料质量均大于50%. 扫描电镜观察微胶囊饲料的表面均有一层较为致密的包衣薄膜. 壁材明胶、乙基纤维素、玉米醇溶蛋白微胶囊饲料的包含率分别为95.4%、95.6%和95.8%; 脂类包埋率分别为72.6%、76.5%和64.3%; 氮保留率分别为53.5%、62.3%和54.6%. 将3种微胶囊饲料分别饲喂15日龄黄姑鱼稚鱼30d. 明胶组和玉米醇溶蛋白组稚鱼的体重、全长均显著高于乙基纤维素组(P0.05), 但成活率差异不显著(P0.05); 明胶组稚鱼的体重、全长和成活率均高于玉米醇溶蛋白组, 但差异均不显著(P0.05). 明胶组稚鱼的胰蛋白酶活力显著高于乙基纤维素组和玉米醇溶蛋白组(P0.05), 但淀粉酶和碱性磷酸酶活力的差异均不显著(P0.05). 与乙基纤维素、玉米醇溶蛋白相比, 明胶更适合作为黄姑鱼稚鱼微胶囊饲料壁材.       

Physical properties of nisin-incorporated gelatin and corn zein films and antimicrobial activity against Listeria monocytogenes

Edible films of gelatin and corn zein were prepared by incorporating nisin to the film-forming solutions. Corn zein film with nisin of 12,000 IU/ml had an increase of 11.6 MPa in tensile strength compared with the control, whereas gelatin film had a slight increase with the increase of nisin concentration added. Water vapor permeability for both corn zein and gelatin films decreased with the increase of nisin concentration, thus providing a better barrier against water. Antimicrobial activity against Listeria monocytogenes increased with the increase of nisin concentration, resulting in 1.4 log cycle reduction for corn zein film and 0.6 log cycle reduction for gelatin film at 12,000 IU/ml. These results suggest that incorporation of nisin into corn zein and gelatin films improve the physical properties of the films as well as antimicrobial activity against pathogenic bacteria during storage, resulting in extension of the shelf life of food products by providing with antimicrobial edible packaging films.     

Preparation of an immobilized two-enzyme system, beta-amylase-pullulanase, to an acrylic copolymer for the conversion of starch to copolymer for the conversion of starch to maltose. I. Preparation and stability of immobilized beta-amylase

β-Amylase (EC 3.2.1.2), obtained from barley, was chemically attached to a crosslinked copolymer of acrylamide-acrylic acid using a water-soluble carbodiimide. The derivative showed 23% β-amylase activity in relation to that of free enzyme with a coupling yield of 40% based on the amount of added β-amylase. In order to find optimal coupling conditions, the effect of pH and different carbodiimide concentrations was investigated. The enzymic activity associated with different β-amylase concentrations was further outlined. A slightly increased operational stability for the enzyme upon immobilization was observed. Markedly improved operational stability has been obtained by coupling in the presence of reduced glutathione of bovine serum albumin.     

Evaluation of allergenic potential for rice seed protein components utilizing a rice proteome database and an allergen database in combination with IgE-binding of recombinant proteins

Among 131 rice endosperm proteins previously identified by MS-based proteomics, most of the proteins showed low or almost no sequence similarity to known allergens in databases, whereas nine proteins did it significantly. The sequence of two proteins showed high overall identity with Hsp70-like hazel tree pollen allergen (Cor a 10) and barley α-amylase (Hor v 16), respectively, whereas the others showed low identity (28–58%) with lemon germin-like protein (Cit l 1), corn zein (Zea m 50 K), wheat chitinase-like xylanase inhibitor (Tri a XI), and kinase-like pollen allergen of Russian thistle (Sal k 1). Immuno-dot blot analysis showed that recombinant proteins for these rice seed homologs were positive in the IgE-binding, but not necessarily similarity dependent, from some allergic patients. These results suggest that utilization of proteome and sequence databases in combination with IgE-binding analysis was effective to screen and evaluate allergenic potential of rice seed protein components.     

Imaging the ordered arrays of water-soluble protein ferritin with the atomic force microscope

Individual water-soluble molecules of the protein ferritin have been imaged on a silicon surface in pure water at room temperature with the atomic force microscope (AFM). The ferritin molecules formed an ordered monolayer by binding to a charged polypeptide monolayer of poly-1-benzyl-L-histidine (PBLH) spread at the air-water interface. The film, fully wetted with water, was horizontally transferred onto an alkylated silicon wafer for AFM imagings. The hexagonal arrangement of ferritin molecules was imaged with high reproducibility on the whole surface of the film, since the forces between cantilever and the sample could be kept sufficiently smaller than 10^-10 N, mainly due to a “self-screening effect” of the surface charges of the ferritin-PBLH layer. This is the first observation of two-dimensional ordered arrays of water-soluble protein molecules directly confirmed by AFM with molecular resolution.     

Biodegradable biocomposite films based on whey protein and zein: barrier, mechanical properties and AFM analysis

Whey and zein protein are byproducts of the food industries and have good film making properties. Single and laminated films were produced from zein protein and whey protein and their film properties were studied. Glycerol and olive oil were used as plasticizer for the single and laminated films. The laminated films exhibited higher ultimate tensile strength (UTS) than the single whey protein films (260% and 200% in the whey-zein-glycerol and whey-zein-olive oil films, respectively). The UTS of the whey protein films increased 2-3-fold after lamination. The laminated films showed higher barrier properties than the single whey protein films (180% in the whey protein-zein-glycerol films and 200% in the whey protein-zein-olive oil films in comparison to single whey protein films) and lower than the single zein films.     

Adhesion behavior of peritoneal cells on the surface of self-assembled triblock copolymer hydrogels

Adhesion behavior of cells to the surface of physical hydrogel membranes prepared by water-induced self-organization of precisely synthesized ABA-triblock copolymers comprised of poly(beta-benzyl L-aspartate) (PBLA) as A segment and poly(ethylene oxide) (PEO, molecular weight = 20 000) as the B segment were investigated. The cast film from the methylenechloride solution of these copolymers swelled in water very rapidly forming hydrogels (100-400% water content of total weight). The content of PBLA affected the strength, the hydrophobicity, and the amount of water involved in the hydrogel surface. During the early stage of cultivation with murine peritoneal cells, cell adhesion on the hydrogels of PEO and PBLA with 18 (20K18) and 25 (20K25) monomeric units was not observed, while adhesion on the hydrogels of PEO and PBLA with 32 (20K32) and 55 (20K55) monomeric units was successful, suggesting more than 12 mol % in PBLA content is necessary for adhesion of these cells. Although cell spreading on the hydrogels of 20K18, 20K25, and 20K32 was not sufficient, the hydrogel of 20K55 allowed cell adhesion and spreading to be bipolar with leading edge whose raffling is active with pseudopodium and lamellipodium as well as PBLA homopolymer, suggesting active motility of these cells. Remarkably, prolonged incubation restored adhesiveness onto the films at 20K18 in contrast to adhesion with 20K25 despite low hydrophobicity. It is conceivable that adaptation of proteins and chemical changes to the surface during the culture period may participate in these phenomena. Mechanical properties and interaction between cell and these copolymer hydrogels could be controlled by composition of block segments, and optimization for implants could also be attainable.     

Cell Surface Hydrophobicity as a Pellicle Formation Factor in Film Strain of Saccharomyces

The film strain of Saccharomyces grows through non-film and film stages. The differences in cell surface hydrophobicity were examined at both stages. The degree of hydrophobic was quantitatively determined by comparing distribution ratios of cells between buffered aqueous and organic solvent phases. The cell surface in the film stage was more hydrophobic than that in the non-film stage, whereas the inherent non-film strain of Saccharomyces always showed low hydrophobicity. These results indicate that the change from non-film to film stage was due to a change in cells from hydrophilic to hydrophobic. The effects of growth conditions on hydrophobicity were further examined with the film strain Saccharomyces bayanus. Ethanol as sole carbon source more efficiently increased hydrophobicity than glucose. The increase in hydrophobicity seemed to depend upon respiration accompanying assimilation of ethanol. It was also found that the addition of a limited amount of biotin, as well as higher pH in medium lowered hydrophobicity. Variation in degree of pellicle formation was positively related to that of cell surface hydrophobicity.     

Zein of maize grain: I — isolation by gel filtration and characterization of monomeric and dimeric species

Unreduced zein chromatographed on Sephadex G 200 in 8 M urea, on G 100 in 1.5 or 2.5% sodium dodecyl sulfate (SDS) and on hydroxypropylated G 100 in 70% ethanol was resolved into two minor fractions A and B and two major ones D and M irrespective of the medium. The quantitative importance of the fraction M was dependent on the isolation conditions of zein. It decreased from 53% of the proteins contained in ethanolic extract and chromatographed as they were extracted, to 40% of the purified zein. The molecular weight values obtained from SDS-polyacrylamide gel electrophoresis and amino acid compositional data indicated that fractions D and M, as isolated from purified zein in the presence of ethanol, represented respectively dimeric and monomeric forms of a mixture of M_r 22 000 and 24 000 polypeptides with threonine or phenylalanine as NH₂-terminal residue.Electrophoretic analysis of selectively carbamylated fraction M on starch gel at pH 3.5 revealed that zein subunits comprised several polypeptides differing in the number and the nature of basic amino acids. At least one of these polypeptides contained one lysyl residue.     

海洋红藻多管藻R—藻红蛋白的体外聚集特性

将海洋红藻R 藻红蛋白 (R PE)吸附到刚揭开的高定向石墨 (HOPG)表面上 ,然后用扫描隧道显微镜 (STM)在纳米尺度上进行直接观察 ,发现纯化的R 藻红蛋白在体外自然聚集时 ,能够“面对面”的聚集在一起 ,形成非常规则的类似藻胆体的杆状结构。将R PE溶于 2 %酒精 /水的混合液中 ,然后滴加于空气 /水界面上 ,具有很好的成膜性能。STM观察结果表明 ,R PE的分子在Langmuir Blodgett膜中的排列方式与其在自然状态下的聚集方式类似 ,圆盘状的R PE分子面对面的聚集在一起形成类似藻胆体的杆状结构 ,这些“杆”状结构进一步聚集在一起形成膜。以上结果表明 ,藻胆蛋白分子在体内以藻胆体的形式存在 ,除了连接肽的作用之外 ,藻胆蛋白自身的结构特性而导致的分子与分子之间的相互作用 ,在藻胆体的组装过程中也起着重要的作用     

Vapor Barrier Properties and Mechanical Behaviors of Composite Hydroxypropyl Methylcelluose/Zein Nanoparticle Films

Composite films of hydroxypropyl methylcellulose and zein nanoparticles (ZNP) were prepared to create a biopolymer-based film with reduced vapor permeability and potential for active-packaging applications. Microscopy verified the dispersion of ZNP with diameter of ~100 nm throughout the width and depth of the films, with ZNP forming sub-micrometer clusters of nanoparticles at loaded volume fractions >0.15. Incorporation of non-hygroscopic ZNP increased film-water contact angles to >70 degrees and decreased water vapor permeability of films by ~10–30%. Extensional measurements of films described an increase in tensile strength from 27 kPa to 49 kPA, a decreased capacity to elongate, and an initial increase followed by gradual decrease in Young’s moduli with increasing ZNP fractions. Decreased elasticity was observed within microscale regions of the films at higher ZNP volume fractions using dynamic force spectroscopy, and the trends were strongly correlated with bulk Young’s moduli of the composite films. A mathematical model rationalized the initially increased and subsequently decreased Young’s modulus by the change in ZNP dispersion/clustering combined with a collapse of the interfacial zone surrounding ZNP.     

Surface hydrophobicity and water transport of the toad urinary bladder: Effects of vasopressin

Summary The present study investigated whether the hydrophobic properties (wettability) of the luminal surface of the toad urinary bladder might play a role in modulating water transport across this epithelium. In the absence of vasopressin (ADH), water transport across the tissue was low, while luminal surface hydrophobicity (water contact angle) was relatively high. Following stimulation by ADH, water transport increased and surface hydrophobicity decreased. The addition of indomethacin to inhibit ADH-induced prostaglandin synthesis did not reduce these actions of ADH. In an attempt to alter water transport in this tissue, a liposomal suspension of surface-active phospholipids was administered to the luminal surface. This addition had no detectable influence on the low basal rates of water transport, but blocked the ADH-induced stimulation of water transport. We suggest that surface-active phospholipids on the toad bladder luminal membrane may contribute to the hydrophobic characteristics of this tissue. ADH may act to decrease surface hydrophobicity, facilitating the movement of water molecules across an otherwise impermeable epithelium. This surface alteration may be associated with the appearance of water channels in the apical membrane.     

Three high-lysine mutations control the level of ATP-binding HSP70-like proteins in the maize endosperm.

The synthesis and deposition of seed storage proteins in maize are affected by several dominant and recessive mutants. The effect of three independent mutations, floury-2 (fl2), Defective endosperm-B30 (De-B30), and Mucronate (Mc), that reduce zein level in the endosperm were investigated. These mutations also control the level of b-70, a polypeptide bound to protein bodies, which is separable into the two isoforms b-70I and b-70II by two-dimensional gel electrophoresis. Both isoforms are overexpressed 10-fold in fl2; however, only b-70I is present in De-B30 and Mc, which contain an amount of total b-70 isoforms fivefold higher than in the wild type. Both b-70I and b-70II resemble heat shock protein (HSP70) in that they bind ATP, cross-react with anti-HSP antibodies, and have N-terminal sequence homology to HSP70. All maize protein body-located b-70 characteristics are typical of those of chaperone-like HSPs. A third protein, b-70III, similar in size to but slightly more acidic than b-70I and b-70II, also binds ATP and reacts with the same antibody, providing evidence for the presence in endosperm extracts of a cytosolic chaperone-like protein. The level of b-70III was not altered by the mutations studied. The results suggested that the repression effect of the three mutations on zein accumulation may be mediated by the alteration of a zein transport or zein assembly process involving b-70I and b-70II.     

Leaf Water Relations, Osmotic Adjustment, Cell Membrane Stability, Epicuticular Wax Load and Growth as Affected by Increasing Water Deficits in Sorghum

A field experiment was conducted with a non-irrigated waterstress treatment and an irrigated control using four sorghum(Sorghum bicolor L. Moench) cultivars. We investigated the effectsof water deficits on leaf water relations, osmotic adjustment,stomatal conductance, cuticular conductance, cell membrane stability(CMS) measured by the polyethylene glycol (PEG) test, epicuticularwax load (EWL), cytoplasmic lipid content, solute concentrationin cell sap, and growth. Osmotic adjustment was observed under water deficit conditions.Lower osmotic potential enabled plants to maintain turgor anddecreased the sensitivity of turgor-dependent processes. Sugarand K were identified as the major solutes contributing to osmoticpotential in sorghum. Sugar and K concentrations in cell sapincreased by 37·4% and 27%, respectively, under waterdeficit conditions in favour of decreasing osmotic potential.Stomatal conductance and cuticular conductance were lower inthe non-irrigated plants. A wide range in CMS among four cultivarswas observed. CMS increased with increasing water deficits.EWL increased on leaves of water deficient plants and was positivelycorrelated with cuticular conductance and CMS. Membrane phospholipidcontent increased in water-stressed plants. CMS as measured by the PEG test, was influenced by EWL, cuticularthickness, and osmotic concentration of leaf tissues. The cultivarswhich maintained higher CMS, higher EWL, lower cuticular conductance,higher turgor and higher osmotic adjustment under water deficitconditions were identified as drought tolerant. Key words: Sorghum bicolor, cell membrane stability, leaf water relationsosmotic adjustment, water stress