Oxidized phospholipids as triggers of inflammation in atherosclerosis

Chronic inflammatory diseases including atherosclerosis are major causes of morbidity and mortality worldwide. However, the factors, which trigger processes that determine the outcome of an inflammatory response, are still poorly understood. Accumulating evidence suggests that certain lipid oxidation products, such as oxidized phospholipids (OxPL), may represent endogenously formed factors that are capable of triggering vascular inflammation. This review will address important questions regarding mechanisms involved in acute and chronic inflammation, and discuss the role of OxPL as key players in triggering the inflammatory response in atherosclerosis. Better understanding of how OxPL contribute to vascular inflammation should lead to new strategies in the treatment of chronic inflammatory disorders.     

Tuning the Functional Properties of Polysaccharide–Protein Bio‐Based Edible Films by Chemical,Enzymatic, and Physical Cross‐Linking

Among natural biopolymers, polysaccharides and proteins are very promising for biodegradable and edible wraps with different characteristics, so that their formulations can be tailor‐made to suit the needs of a specific commodity. Films prepared from polysaccharides have good gas barrier properties but exhibit lower resistance to moisture compared to protein films (edible) or polylactide films (biodegradable). Protein‐based films show better mechanical and oxygen barrier properties compared to polysaccharide films. For that reason, film performances may be enhanced by producing blend systems, where hydrocolloids (mixtures of proteins and/or polysaccharides) form a continuous and more cohesive network. However, the lower water barrier properties of hydrocolloid films and their lower mechanical strength in comparison with synthetic polymers limit their applications in food packaging. Therefore, the enhancement of biopolymer film properties has been studied to attain appropriate applications. This review provides an extensive synthesis of the improvement of the properties of edible polysaccharide–protein films by way of various chemical, enzymatic, and physical methods. These methods primarily aim at improving the mechanical resistance. They also permit to ameliorate the water and gas barrier properties and related functional properties.     

Production of a transglutaminase from Zea mays in Escherichia coli and its impact on yoghurt properties

A gene from Zea mays coding a TGase was expressed in E. coli and identified by Western blotting. Under optimal expression conditions, the production and specific activity of refolded TGZ were 1.41 mg/L and 0.34 U/mg. The activated TGZ was employed to cross‐link milk proteins. The yoghurt treated with TGZ showed a lower syneresis, higher apparent viscosity and texture than untreated yoghurt. The properties of TGZ‐treated sample were better than those of MTG‐treated samples, so TGZ may have potential as an additive in yoghurt manufacture.     

摄食不同来源磷脂对大鼠脂质代谢及脑内磷脂脂肪酸组成的影响

研究了摄食不同来源磷脂对大鼠脂质代谢及其脑内磷脂脂肪酸组成的影响。雄性SD大鼠按体重随机分为大豆油对照组(添加9%)、牛乳磷脂组(添加5%)、大豆磷脂组(添加5%)、蛋黄磷脂组(添加5%),喂食3周。检测了血清总胆固醇(TC)、甘油三酯(TG)、高密度脂蛋白胆固醇(HDL-C)、游离脂肪酸(FFA)及肝脏TC、TG、磷脂(PL)的含量,并用气相色谱法测定了脑内磷脂脂肪酸的组成变化。结果显示:与大豆油对照组相比,3种磷脂均不同程度提高了大鼠体重、脏器指数,蛋黄磷脂效果显著;3种磷脂不同程度降低了血清TC、TG和FFA含量,牛乳磷脂降低血清FFA显著,大豆磷脂降低血清TC、TG显著,蛋黄磷脂降低FFA显著,大豆磷脂显著提升了血清HDL-C含量;3种磷脂不同程度降低了肝脏TC、TG、PL含量,牛乳磷脂与大豆磷脂降低肝脏TG、TC显著,而蛋黄磷脂降低肝脏TG显著;3种磷脂对脑内磷脂脂肪酸组成的影响各不相同,牛乳磷脂显著提高了脑内磷脂饱和脂肪酸含量,而大豆磷脂和蛋黄磷脂提高了DHA等多不饱和脂肪酸含量。研究表明,3种磷脂均有降血脂、肝脂作用,以大豆磷脂作用尤为明显,大豆磷脂和蛋黄磷脂的益智作用可能优于牛乳磷脂。     

磷脂分离、纯化和检测方法的研究进展

综述了磷脂分离提纯方法如溶剂萃取法、柱层析法、超临界流体萃取法、金属沉淀法、酶催化法和膜分离法等,以及磷脂化合物的分析检测方法如薄层层析法、高效液相色谱法和新兴的核磁共振法等的发展研究现状.分析了各种分离检测方法的优缺点,展望了磷脂组分分离检测方法的发展方向.     

Purification,characterization, and inhibition sensitivity of peroxidase from wheat (Triticum aestivum ssp. vulgare)

The purification and characterization of peroxidase is currently growing interests since peroxidases have implications in various industrial and biochemical applications. In this study, wheat peroxidase was purified using (NH₄)₂SO₄ precipitation, CM-Sephadex cation exchange, and gel filtration chromatographies. Enzyme purity and molecular mass were checked by sodium dodecyl sulphate polyacrylamide gel electrophoresis. Enzyme kinetics was studied using two substrates: guaiacol and hydrogen peroxide (H₂O₂). K_m and V_max values were calculated from Lineweaver-Burk graph for each substrate. Wheat peroxidase activity has been enhanced 284-fold. Wheat peroxidase had molecular mass of 38.8 kDa. K_m values for guaiacol and H₂O₂ were found as 2.467 mM and 7.307 mM, respectively. The pH and temperature optima were 5.5 and 40.0°C, respectively. Also, the enzyme was highly inhibited by citric acid and Cetyltrimethylammonium bromide.     

Natural phospholipids: Occurrence,biosynthesis, separation,identification, and beneficial health aspects

During the last years, phospholipids (PLs) have attracted great attention because of their crucial roles in providing nutritional values, technological and medical applications. There are considerable proofs that PLs have unique nutritional benefits on human health, such as reducing cholesterol absorption, improving liver functions, and decreasing the risk of cardiovascular diseases. PLs are the main structural lipid components of cell and organelle membranes in all living organisms, and therefore, they occur in all organisms and the derived food products. PLs are distinguished by the presence of a hydrophilic head and a hydrophobic tail, consequently they possess amphiphilic features. Due to their unique characteristics, the extraction, separation, and identification of PLs are critical issues to be concerned. This review is focused on the content of PLs classes in several sources (including milk, vegetable oils, egg yolk, and mitochondria). As well, it highlights PLs biosynthesis, and the methodologies applied for PLs extraction and separation, such as solvent extraction and solid-phase extraction. In addition, the determination and quantification of PLs classes by using thin layer chromatography, high-performance liquid chromatography coupled with different detectors, and nuclear magnetic resonance spectroscopy techniques.     

大豆磷脂中PC、PE、PI测定方法的研究

为准确快速地对大豆磷脂中的主要成分磷脂酰胆碱（PC）、磷脂酰乙醇胺（PE）、磷脂酰肌醇（PI）进行定量分析,对分析柱、流动相、检测波长进行了选择与优化,最终建立了以Lichrosorb Si-60为分析柱,205nm波长下,以V（正己烷）：V（异丙醇）：V（1％乙酸）=8：8：1为流动相的高效液相色谱测定法。     

Rheological,gelling and emulsifying properties of a glycosylated and cross‐linked caseinate generated by transglutaminase

The impacts of oligochitosan glycosylation and cross‐linking on some properties of a commercial caseinate were investigated in this study. The glycosylated and cross‐linked caseinate with glucosamine content of 4.74 g kg^?1 protein was generated by transglutaminase (TGase) and oligochitosan at pH 7.5 and 37 °C, with fixed substrate molar ratio of 1:3 (acyl donor to glucosamine acceptor), caseinate content of 50 g L^?1, TGase of 10 kU kg^?1 protein and reaction time of 3 h, respectively. In comparison with the caseinate, the glycosylated and cross‐linked caseinate had decreased reactable amino groups (0.58 vs. 0.51 mol kg^?1 protein), higher apparent viscosity, decreased emulsifying activity index (about 14.5%) and statistically unchanged emulsion stability index (92.6 vs. 90.5%). Based on the mechanical spectra of the acid‐induced gels, the glycosylated and cross‐linked caseinate showed shorter gelation time (95 vs. 200 or 220 min) than the caseinate or cross‐linked caseinate. The gels prepared from the glycosylated and cross‐linked caseinate also had enhanced hardness, springiness and cohesiveness. The results indicated that TGase‐mediated oligochitosan glycosylation and cross‐linking has the potential to obtain new protein ingredients.     

4-Hydroxynonenal and cholesterol oxidation products in atherosclerosis

4-Hydroxynonenal (HNE) is by far the most investigated aldehydic end-product of oxidative breakdown of membrane n-6 polyunsaturated fatty acids. Its potential involvement in the pathogenesis of atherosclerosis has been corroborated by its consistent detection in both oxidized LDL and fibrotic plaque in humans. HNE has been shown to activate both macrophage and smooth muscle cells, i.e. the two key cell types in chronic inflammatory processes characterized by excessive fibrogenesis. By signalling to the nucleus, the aldehyde may up-regulate in these cells both expression and synthesis of monocyte chemotactic protein 1 (MCP-1) and transforming growth factor beta1 (TGFbeta1). Oxysterols, namely 27 carbon atoms oxidation products of cholesterol, are found in relatively high amount in LDL from hypercholesterolemic individuals and are consistently detectable in foam cells and necrotic core of human atherosclerotic lesion. As for HNE, the challenge of cells of the macrophage lineage with a mixture of oxysterols like that detectable in hypercholesterolemic individuals led to a marked overexpression of TGFbeta1 and MCP-1. Both HNE and oxysterols then appear to be candidates for a primary role in the progression of the atherosclerotic process.     

Effect of microbial transglutaminase on autolysis and gelation of lizardfish surimi

In the absence of microbial transglutaminase (MTGase), the textural properties of lizardfish surimi (Saurida spp) improved when pre‐incubated at 4 and 25 °C for 24 and 4 h, respectively. MTGase optimally catalyzed incorporation of monodansylcadaverine (MDC) into surimi at 40 °C. Addition of MTGase appeared to reduce autolytic activity at 25 and 40 °C, but had no effect on autolytic activity at 65 °C. Breaking force and deformation of lizardfish surimi significantly improved when 0.1 unit MTGase g^?1 surimi (1.8 g kg^?1) was added and pre‐incubated at either 25 or 40 °C. Textural properties improved concomitant with cross‐linked polymers of myosin heavy chain and tropomyosin, but not actin. Addition of MTGase also improved the storage modulus (G′). The gel network of surimi mixed with MTGase and pre‐incubated at 40 °C readily formed during the pre‐incubation period, while formation of the gel network began at 48.1 °C in the absence of MTGase. Copyright © 2005 Society of Chemical Industry     

A study on the preparation and some functional properties of a cross‐linked casein–gelatin composite by a microbial transglutaminase

A microbial transglutaminase (TGase) was used in this work as biocatalyst to prepare a cross‐linked casein–gelatin composite, a modified protein product with 4‐hydroxyproline about 41 mg g^?1 peptides. Some cross‐linking conditions such as total protein content, the ratio of caseinate to gelatin and original pH were fixed at 5% (w/v), 4:1 (w/w) and 7.5, respectively. Other suitable conditions selected by single factor trials were TGase addition of 20 U g^?1 peptides, reaction temperature of 45 °C and reaction time of 4 h. Peptide profiles from SDS‐PAGE analysis showed the composite was peptide polymers. Compared to that of the original caseinate or the cross‐linked caseinate, the dispersion of the composite exhibited a markedly enhanced apparent viscosity, storage modulus and viscous modulus. Meanwhile, the composite also showed a better water holding capacity, unchanged oil binding capacity and lower enzymatic digestibility in vitro, conferring its applicability as a new protein ingredient.     

Textural and biochemical changes during ripening of old-fashioned salted herrings

BACKGROUND: Understanding of the biochemical reactions taking place during ripening of salted herring is still rather limited. Therefore, salted herrings were traditionally produced and the impact of the brine composition was evaluated in relation to the development of the characteristic texture of salted herrings. The aim of this study was to measure the texture changes during ripening using two different methods and to correlate the texture changes with brine composition and with biochemical modifications at the molecular level. RESULTS: During ripening (up to 151 days), hardness was higher in salted herrings compared to raw herrings, irrespective of the brine composition. However, the increase in hardness of herring prepared with extra brine occurred later. After prolonged storage (371 days), hardness was found for both batches to decrease to the level of raw herring. The increase in hardness during the ripening period could be explained by free‐radical‐induced cross‐linking of myosin and the formation of aggregates. In addition, degradation of these aggregates correlated with the decrease in hardness observed at 371 days. CONCLUSIONS: Texture changes during ripening of salted herrings can be explained by oxidative reactions inducing myosin cross‐linking followed by subsequent degradation of these myosin aggregates. The brine composition might play a role in the development of herring texture but this need to be investigated in more details. Copyright © 2010 Society of Chemical Industry     

大豆磷脂软胶囊中铅、铬、镉、砷4种微量重金属的检测方法研究

为了方便、快速、准确地检测大豆磷脂软胶囊中铅、铬、镉、砷4种微量重金属元素的含量,建立了一种冷冻快速粉碎-微波消解的前处理方式,采用电感耦合等离子体质谱仪(ICP-MS)进行测定。试验结果表明:经冷冻快速粉碎后的软胶囊壳颗粒均一;微波消解耗时短、操作简便、耗费试剂少,ICP-MS测定结果显示铅、铬、镉、砷4种重金属的平均回收率在82. 6%～92. 9%之间。试验结果满意,可为日常工作中测定软胶囊类产品中重金属前处理作参考。     

Protein Oxidation at Different Salt Concentrations Affects the Cross‐Linking and Gelation of Pork Myofibrillar Protein Catalyzed by Microbial Transglutaminase

In a fabricated then restructured meat product, protein gelation plays an essential role in producing desirable binding and fat‐immobilization properties. In the present study, myofibrillar protein (MFP) suspended in 0.15, 0.45, and 0.6 M NaCl was subjected to hydroxyl radical stress for 2 or 24 h and then treated with microbial transglutaminase (MTGase) in 0.6 M NaCl (E : S = 1 : 20) at 4 and 15 °C for 2 h. Protein cross‐linking and dynamic rheological tests were performed to assess the efficacy of MTGase for mediating the gelation of oxidized MFP. MTGase treatments affected more remarkable polymerization of myosin in oxidized MFP than in nonoxidized, especially for samples oxidized at 0.6 M NaCl. Notably, the extent of MTGase‐induced myosin cross‐linking at 15 °C in oxidized MFP improved up to 46.8%, compared to 31.6% in nonoxidized MFP. MTGase treatment at 4 °C for MFP oxidized in 0.6 M NaCl, but not MFP oxidized in 0.15 M NaCl, produced stronger gels than nonoxidized MFP (P < 0.05). The final (75 °C) storage modulus (G′) of oxidized MFP gels was significantly greater than that of nonoxidized, although the G′ of the transient peak (～44.5 °C) showed the opposite trend. Overall, oxidation at high salt concentrations significantly improved MTGase‐mediated myosin cross‐linking and MFP gelation. This might be because under this condition, MTGase had an increased accessibility to glutamine and lysine residues to effectively initiate protein–protein interactions and gel network formation.     

Zinc‐loaded whey protein nanoparticles prepared by enzymatic cross‐linking and desolvation

Zinc‐loaded whey protein nanoparticles were prepared by enzymatic cross‐linking whey protein followed by ethanol desolvation. Whey protein isolate (WPI) was denatured by heating (80 °C for 15 min) at pH 7.0 and then cross‐linked by transglutaminase at 50 °C for 4 h while stirring. Transglutaminase was inactivated by heating at 90 °C for 10 min, and then, ZnSO₄·7H₂O (1–10 mm ) was added. Zinc‐loaded whey protein nanoparticles were formed by adding ethanol at one to five times the volume of the protein solution at pH 9.0. The desolvated solutions were diluted by adding distilled water at ratio of 1:100 (w/v) immediately after desolvation. Dynamic light scattering (DLS) data showed that the particle size of zinc‐loaded whey protein nanoparticles increased with the amount of zinc and the volume of ethanol. Scanning electron microscopy micrographs revealed an almost spherical morphology for zinc‐loaded whey protein nanoparticles. The zinc loading efficiency was determined ranging from 76.7% to 99.2%. In vitro test data showed that the zinc release rate was low in simulated gastric fluid but high in simulated intestinal fluid. The results indicated that enzymatic cross‐linked whey protein nanoparticles may be used as a good vehicle to deliver zinc as a supplement.