Cellular Disulfide Bond Formation in Bioactive Peptides and Proteins

Bioactive peptides play important roles in metabolic regulation and modulation and many are used as therapeutics. These peptides often possess disulfide bonds, which are important for their structure, function and stability. A systematic network of enzymes—a disulfide bond generating enzyme, a disulfide bond donor enzyme and a redox cofactor—that function inside the cell dictates the formation and maintenance of disulfide bonds. The main pathways that catalyze disulfide bond formation in peptides and proteins in prokaryotes and eukaryotes are remarkably similar and share several mechanistic features. This review summarizes the formation of disulfide bonds in peptides and proteins by cellular and recombinant machinery.     

Preparation and Properties of Bioactive Composite Based on Bioactive Glass and Poly-L-Lactide

Bioactive and bioresorbable composite was fabricated based on poly-L-lactide (PLLA) and bioactive glass (average particle size: 4.24 µm) by the combination of solvent evaporation technique and hot pressing. Bioactive glass granules are distributed homogeneously in the composite. With the increasing of the amount of bioactive glass, the bending strength and shearing strength of composite decrease while the bending modulus increases. PLLA/bioactive glass composites present a typical morphology of brittle failure with a smooth fracture surface. The biocompatibility test shows that the bioactive glass existing in the composite facilitates both adhesion and proliferation of rat fibroblast on the PLLA/bioactive glass composite film.     

Antioxidant and ACE Inhibitory Bioactive Peptides Purified from Egg Yolk Proteins

Protein by-products from the extraction of lecithin from egg yolk can be converted into value-added products, such as bioactive hydrolysates and peptides that have potential health enhancing antioxidant, and antihypertensive properties. In this study, the antioxidant and angiotensin converting enzyme (ACE) inhibitory activities of peptides isolated and purified from egg yolk protein were investigated. Defatted egg yolk was hydrolyzed using pepsin and pancreatin and sequentially fractionated by ultrafiltration, followed by gel filtration to produce egg yolk gel filtration fractions (EYGF). Of these, two fractions, EYGF-23 and EYGF-33, effectively inhibited the peroxides and thiobarbituric acid reactive substance (TBARS) in an oxidizing linoleic acid model system. The antioxidant mechanism involved superoxide anion and hydroxyl radicals scavenging and ferrous chelation. The presence of hydrophobic amino acids such as tyrosine (Y) and tryptophan (W), in sequences identified by LC-MS as WYGPD (EYGF-23) and KLSDW (EYGF-33), contributed to the antioxidant activity and were not significantly different from the synthetic BHA antioxidant. A third fraction (EYGF-56) was also purified from egg yolk protein by gel filtration and exhibited high ACE inhibitory activity (69%) and IC₅₀ value (3.35 mg/mL). The SDNRNQGY peptide (10 mg/mL) had ACE inhibitory activity, which was not significantly different from that of the positive control captopril (0.5 mg/mL). In addition, YPSPV in (EYGF-33) (10 mg/mL) had higher ACE inhibitory activity compared with captopril. These findings indicated a substantial potential for producing valuable peptides with antioxidant and ACE inhibitory activity from egg yolk.     

生物活性玻璃多孔材料的制备及性能研究

采用溶胶-凝胶法制备生物活性玻璃58S及77S;通过熔融法制备生物活性玻璃45S5,分别向上述3种生物活性玻璃粉体以及它们的混合物中添加一定比例的造孔剂,通过一定的烧结工艺制成具有不同组成的生物活性多孔材料,利用体外实验方法结合DTA,SEM及FTIR等材料显微结构及性能研究手段分析比较了各种多孔材料的显微结构、表面形貌、抗折强度及生物活性.研究表明:58S和45S5混合制备的多孔材料是一种具有良好生物活性和生物矿化特性的生物材料,可用于制备骨缺损填充材料和骨组织工程支架.     

牛乳清结晶条件的探索及其结晶体形貌

以脱脂及去酪蛋白的牛乳清为原料,利用紫外分光光度法及SDS-PAGE电泳技术,在p H 4.7~8.0,Na Cl浓度0.5~2.0 mol/L条件下,对其结晶情况进行了研究。结果表明:牛乳清蛋白中的免疫球蛋白G(Ig G)是一种理想的目标蛋白,而p H 7.0则是得到Ig G的理想p H。最后还利用了工业相机及荧光倒置显微镜对牛乳清结晶体进行了拍摄,发现其中主要有长方晶、四角晶、菱方晶三种结晶体形貌。     

The Preparation and Properties of Bioactive Composites Based on Modification Bioactive Glass and Poly(Lactide-Co-Glycolide)

PLGA/bioactive glass composites were prepared as promising bone-repairing materials. The bioactive glass was fabricated by Sol-gel method. Surface Modification was done to improve the phase compatibility between polymer and the inorganic phase. PLGA/bioactive glass composites were successfully prepared via solution dispersion method. Composites films with different content of bioactive glass were obtained. The mechanical properties of composites were characterized by the three-point-bending test and composites films were investigated by in vitro bioactive test. These results indicate that the fractions of bioactive glass in composites produce no significant influence on mechanical properties. Compared to pure PLGA film the PLGA/bioactive glass composites demonstrate greater capability to induce the formation of apatite particles on the film surface.     

牛神经生长因子的研制

目的 寻找新的制备神经生长因子的材料和方法。方法 利用牛精液为原料，进行两次阳离子交换层析。结果 获得了纯的牛神经生长因子，相对分子质量为30000，比活性为400000BU/mg，FPLC检测结果为一个峰，电泳检测纯度大于95％。结论 可以从牛精液中制备神经生长因子。     

水热法制备Ca-P-Si-Na生物活性玻璃陶瓷

采用水热法合成了Ca-P-Si-Na生物活性玻璃陶瓷。实验首先将质量分数为49．6％SiO2．22．9％CaO，21．5％Na20，6．0％P2O5生料置于聚氨酯球磨罐里混合球磨5h，然后施以5～20MPa的压力压制成块，置于高压釜内在200～250％水热处理12～72h。样品检测采用体外实验（in vitro）方法，通过把样品在模拟体液里浸泡不同的时间，观察其表面反应特征；采用XRD分析产物的晶相和FTIR转换红外光谱表征其生物活性，以及采用SEM研究了材料的微观结构。结果表明：该生物活性玻璃陶瓷的主晶相是Na2CaSi3O8；玻璃陶瓷的生物活性基于磷灰石相的存在。     

新生牛肝活性肽的制备及其毒性检测

目的制备新生牛肝活性肽并评价其安全性。方法采用膜法分离制备新生牛肝活性肽。将3批制品于37～40℃,75%相对湿度条件下存放3个月,以多肽含量为指标观察其稳定性,并进行急性毒性试验、小鼠骨髓细胞微核试验、Ames试验、小鼠精子畸形试验和大鼠喂养试验。结果制备的3批新生牛肝活性肽存放3个月后,多肽含量无明显下降,质量稳定。小鼠和大鼠经口灌人大于20.0g/kg体重的新生牛肝活性肽,均无急性毒性。3种致突变试验均未显示出致突变性,大鼠喂养试验各项指标均未见明显毒性。结论新生牛肝活性肽未表现出明显毒性。     

Preparation and Thermoplastic Processing of Modified Plant Proteins

Native plant proteins such as gluten, zein, soy and pea protein were chemically modified by acylation reactions using palmitic acid chloride and alkenyl‐substituted succinic anhydrides, respectively. The goal of this work was the development of novel, biodegradable protein materials, which are processable by thermoplastic shaping in extruders. Structures and properties of modified plant proteins were characterized by elementary analysis, IR, DSC, TGA, water retention analysis, and tensile tests. The biodegradability of the acylated protein derivatives has been demonstrated. It can be concluded that the chosen plant proteins are suitable for acylation reactions leading to fusible thermoplastic materials with improved water‐resistance. However, resultant extruded articles possess mostly high brittleness combined with low tensile strength. An improved processability and mechanical performance of the acylated products can be achieved by addition of only 10% glycerol.

     

新生牛肝活性肽对小鼠血清中ALT和AST酶活力的影响

目的观察新生牛肝活性肽对四氯化碳引起的小鼠化学性肝损伤的保护作用。方法采用四氯化碳致小鼠化学性肝损伤模型,设新生牛肝活性肽低、中、高剂量组、模型对照组和正常对照组,分别灌胃给药,观察各组小鼠肝损伤情况。结果新生牛肝活性肽高剂量组可有效降低模型小鼠血清中ALT,但AST降低不明显。结论新生牛肝活性肽对化学性肝损伤具有辅助保护作用。     

HA生物活性陶瓷涂层制备方法研究进展

阐述了国内外学者对金属基羟基磷灰石生物活性涂层的研究状况,论述了羟基磷灰石涂层的制备方法,认为该材料是最具有发展前景的生物硬组织替代材料之一。     

除草剂混用及其药效评价方法

多种方法可评价除草剂混用后的药效,如Gowing法、Colby法、Sun＆Johnson法、等效线法（千版法）等。用于评价除草剂混用后的药效的各方法均有其优点及不足之处,且有良好的一致性。     

Biomimetic Preparation and Characterization of Bioactive Coatings on Alumina and Zirconia Ceramics

For the preparation of bioactive coatings on alumina and zirconia ceramic surfaces a fast biomimetic method using a supersaturated solution containing Na⁺, Ca²⁺, Cl⁻, HCO₃⁻, and PO₄³⁻ ions was used. The coatings were analysed with the use of an X-ray diffraction spectrometer and a transmission electron microscope equipped with an energy-dispersive spectroscopy detector. After the precipitation both coatings were composed of poorly crystallized, nanosized, plate-like particles with the octacalcium phosphate (OCP) crystal structure. The adhesion of the coatings was improved by a heat treatment at 1050°C for 1 h. During this heat treatment the calcium phosphate layer, deposited from a supersaturated solution onto the surface of the substrates, was sintered to form a dense coating. At the same time the OCP crystal structure was transformed into that of hydroxyl apatite, the coating's crystallinity was increased, and the particles grew isotropically up to 300 nm in size. The bioactivity of the coated ceramic was confirmed before and after the heat treatment using a simple simulated body fluid test.     

Regulation of Cholesterol Metabolism by Bioactive Components of Soy Proteins: Novel Translational Evidence

Hypercholesterolemia represents one key pathophysiological factor predisposing to increasing risk of developing cardiovascular disease worldwide. Controlling plasma cholesterol levels and other metabolic risk factors is of paramount importance to prevent the overall burden of disease emerging from cardiovascular-disease-related morbidity and mortality. Dietary cholesterol undergoes micellization and absorption in the small intestine, transport via blood, and uptake in the liver. An important amount of cholesterol originates from hepatic synthesis, and is secreted by the liver into bile together with bile acids (BA) and phospholipids, with all forming micelles and vesicles. In clinical medicine, dietary recommendations play a key role together with pharmacological interventions to counteract the adverse effects of chronic hypercholesterolemia. Bioactive compounds may also be part of initial dietary plans. Specifically, soybean contains proteins and peptides with biological activity on plasma cholesterol levels and this property makes soy proteins a functional food. Here, we discuss how soy proteins modulate lipid metabolism and reduce plasma cholesterol concentrations in humans, with potential outcomes in improving metabolic- and dyslipidemia-related conditions.     

Preparation of Rapeseed Proteins by Extraction,Ultrafiltration and Diafiltration

From industrial Rapeseed mean (Brassica napus, Var. Sollux) different protein preparates are prepared by varying extractions (water extraction, extraction with 1% CuSO₄ solution, extraction with 5% sodium chloride solution) following ultrafiltration (UF), diafiltration (DF) and drying. The UF, UF/DF respectively is a comparatively simple process for concentration and purification of all solved proteins without losses (globulins and above all albumins). The UF/DF treatment of a 5% sodium chloride solution protein extract leads to a preparate containing more than 90% protein in which glucosinolates and splitting products and also phytate are not detectable.     

Preparation of a Bioactive Poly(methyl methacrylate)/Silica Nanocomposite

The nanocomposite of a poly(methyl methacrylate)/silica containing calcium salt was synthesized through the sol–gel method. Methyl methacrylate was co-polymerized with 3-(trimethoxysilyl)propyl methacrylate and then co-condensed with tetraethyl orthosilicate and calcium nitrate tetrahydrate. Low crystalline hydroxycarbonate apatite was successfully formed on the surface after soaking in simulated body fluid for 1 week at 36.5°C. This study demonstrates that this nanocomposite may be used as a bioactive bone substitute or filler for poly(methyl methacrylate) bone cement.     

Functional Studies of Plant Latex as a Rich Source of Bioactive Compounds: Focus on Proteins and Alkaloids

Latex, a sticky emulsion produced by specialized cells called laticifers, is a crucial part of a plant’s defense system against herbivory and pathogens. It consists of a broad spectrum of active compounds, which are beneficial not only for plants, but for human health as well, enough to mention the use of morphine or codeine from poppy latex. Here, we reviewed latex’s general role in plant physiology and the significance of particular compounds (alkaloids and proteins) to its defense system with the example of Chelidonium majus L. from the poppy family. We further attempt to present latex chemicals used so far in medicine and then focus on functional studies of proteins and other compounds with potential pharmacological activities using modern techniques such as CRISPR/Cas9 gene editing. Despite the centuries-old tradition of using latex-bearing plants in therapies, there are still a lot of promising molecules waiting to be explored.