Application of high density steam flash-explosion in protein extraction of soybean meal

The high density steam flash-explosion (HDSFE) was used to extract protein from soybean meal. Soybean meal samples were treated at 1.3 MPa and 1.8 MPa for 60 s, 120 s and 180 s, respectively. After HDSFE treatment at 1.8 MPa for 180 s, the extraction yield of protein was increased from 50.50% to 65.66% compared with untreated soybean meal. The emulsification properties and fat-binding capacity of soy protein isolate (SPI) extracted from soybean meal treated by HDSFE were all improved compared with SPI extracted from untreated soybean meal and white flakes. Molecular weight distribution analysis of SPI showed that after HDSFE treatment the peak with molecular weight about 504 kDa and 43.3 kDa disappeared and the peak with molecular weight about 669 kDa increased indicating protein aggregation. Gel electrophoresis showed that high molecular weight aggregates of protein have been formed by covalent bond.     

超声波辅助SDS反胶束前萃花生蛋白研究

采用SDS(十二烷基磺酸钠)/异辛烷―正辛醇反胶束体系萃取花生蛋白,并采用超声波辅助萃取,主要研究全脂花生粉加入量、缓冲溶液pH值、萃取时间、萃取温度、超声波功率、KCl浓度、SDS浓度、Wo对蛋白萃取率影响。设计正交实验优化萃取工艺,结果表明,最优前萃工艺条件为:花生粉加入量0.015 g/mL、缓冲溶液pH值9、萃取时间40 min、萃取温度35℃、超声波功率270 W、KCl浓度0.25 mol/L、SDS浓度0.07 g/mL、Wo为24;在此条件下,花生蛋白萃取率为89.62%±1.15%。     

Effect of Slurry Ice on the Functional Properties of Proteins Related to Quality Loss during Skipjack Tuna (Katsuwonus pelamis) Chilled Storage

The effect of slurry ice on the quality of Skipjack tuna (Katsuwonus pelamis) during chilling storage was investigated and compared to flake ice. Slurry ice‐treated samples showed significantly higher springiness and chewiness variables than the blank and flake ice‐treated samples (P < 0.05). The growth of microorganisms in tuna muscle treated with slurry ice was also down significantly (P < 0.05), and the total aerobic counts didn't reach higher scores than 5.0 log CFU/g during the whole chilling storage. Additionally, the myofibrillar protein, Ca²⁺‐ATPase activity, and total sulfydryl (SH) content in muscle treated with slurry ice were all significantly higher than the blank and flake‐iced samples (P < 0.05). This was probably due to the faster cooling, subzero final‐temperature, and larger heat exchange derived from slurry ice. Standard error of mean and sodium dodecyl sulfate–polyacrylamide gel electrophoresis results also confirmed that slurry ice treatment could effectively retard the degradation of myofibrillar proteins and showed a positive effect on the stability of tissue structures.     

Newly designed polyacrylamide/dextran gels for electrophoresis protein separation: synthesis and characterization

Newly designed gels for electrophoresis protein separation were synthesized from acrylamide, N,N′‐methylenebis (acrylamide) and dextran mixtures. Radical polymerization was initiated by ammonium persulfate and N,N,N′,N′‐tetramethylethylenediamine. The time dependence of absorbance during polymerization was monitored using UV‐visible spectroscopy. The exothermic polymerization process exhibited a sharp rise of temperature reminiscent of the Trommsdorff effect. The swelling kinetics of the synthesized gels was examined in deionized water and buffer solutions. One of the challenges was to find an alternative to commercial products, sold as mixtures with no detailed chemical contents, commonly used in sodium dodecylsulfate polyacrylamide gel electrophoresis (SDS‐PAGE) for protein separation. For this reason, a systematic comparison was made of the properties of one of the most commonly used commercial gels, Duracryl^? from Genomics Solution Inc., and those of the synthesized polyacrylamide/dextran gels. Copyright © 2011 Society of Chemical Industry     

Purification and characterization of parvalbumins from silver carp (Hypophthalmichthy molitrix)

BACKGROUND: As the largest producer and consumer of freshwater fish in the world, many people suffer from allergy for consuming freshwater fish in China. However, the allergen profiles of freshwater fish are rarely known. RESULTS: Parvalbumins (PVs) from the white muscle of silver carp (Hypophthalmichthy molitrix) were purified by ammonium sulfate fractionation and column chromatography including DEAE‐Sepharose and Superdex 75. Three PV isoforms—PV‐I, PV‐II, and PV‐III—were obtained and their molecular masses as estimated by tricine–sodium dodecyl sulfate–polyacrylamide gel electrophoresis were 12, 11, and 14 kDa, respectively. All the PVs could be detected by anti‐frog PV monoclonal antibody. PV‐I and PV‐II were quite possibly glycoproteins, while PV‐III was not glycosylated, as analyzed by periodic acid–Schiff (PAS) staining. Thermal stability revealed that PV‐I and PV‐II easily formed polymers, while these proteins were stable in a pH range of 4.0–10.0. A PV gene encoding 110 amino acid residues was cloned and it revealed high identity with PVs from other species of fish. CONCLUSION: Three isotypes of PV were purified to homogeneity and one distinct PV gene was cloned in silver carp white muscle. Copyright © 2010 Society of Chemical Industry     

Purification and structural characterisation of lipid transfer protein from red wine and grapes

Lipid transfer proteins (LTP) play a major role in plant defence and are of particular interest due to their known ability to cause allergic reactions. These proteins are expressed in grapes and also remain detectable after vinification, especially in red wine. However, it remains unknown whether the protein undergoes any changes during the vinification process. Here, we present a purification method for LTPs from Dornfelder grapes and wine. By liquid-chromatography–mass spectroscopy (LC–MS/MS) we identified LTPs from two different species (Vitis vinifera and Vitis aestivalis). Additionally, the purified LTPs were characterised using spectrometric methods, confirming their high purity and structural stability during vinification. We conclude that LTPs are resistant to the alcohol content (13.5 vol%), acidic milieu of wine and other ingredients present during the vinification process, indicating that the allergenic potential of grape LTP is not diminished by the vinification process.     

TETRA电路模式控制实体信令软件实现

TETRA作为全球性数字集群标准,其技术和市场都在迅速发展。本文详细分析了TETRA移动台电路模式控制实体(CMCE-MS)协议,并给出其软件设计与实现的详细方案。     

珊瑚状分级微纳米结构聚苯胺的制备、表征及其气敏性能研究

采用简单的阴离子表面活性剂诱导原位化学聚合法,以过硫酸铵(APS)为氧化剂,在十二烷基硫酸钠(SDS)的盐酸溶液中制得了珊瑚状聚苯胺( PANI)微纳米材料.对所制备的PANI分别采用傅里叶变换红外光谱(FT-IR)、场发射扫描电镜(FE-SEM)进行表征.实验结果表明加入SDS后,可以得到一种珊瑚状分级结构PANI微...     

高光谱空间降采样独立成分特征分离

提出一种空间降采样独立成分特征分离方法,用于缩短独立成分分析(ICA)法在高光谱图像特征分离时的运算时间。该方法通过对高光谱图像的二维像素空间进行网格划分得到较小的窗口;基于光谱相似性测度法度量每个窗口中中心像素与周围像素的距离。然后舍弃这段距离小于阈值的周围像素,而将大于阈值的周围像素和中心像素作为样本量进行FastICA,获取投影矩阵变换原始数据,得到特征分离的ICA成分。对比了传统ICA与空间降采样(SDS)ICA(SDS_ICA)的性能,研究了降采样阈值参数、降采样窗口参数及初始投影矩阵对SDS_ICA特征分离性能及运行时间的影响。实验结果表明:应用SDS_ICA时,仅设置适中的阈值和不敏感的窗口大小参数,就能保持与传统ICA相近的特征分离性能,运行时间减少了30%以上。该方法适合应用于高光谱准实时特征提取、数据降维及目标探测等领域。     

Antimicrobial peptides and their superior fluorinated analogues: structure-activity relationships as revealed by NMR spectroscopy and MD calculations

The conformations of two synthetic pentapeptides with antimicrobial activity and their 4-fluorophenylalanine (Pff)-containing analogues (ArXArXAr-NH(2); Ar=Phe, Pff; X=Lys, Arg) have been studied. NMR experiments carried out both in aqueous fluoroalcohol solutions and SDS micelles permitted their interactions with membrane-like environments to be explored. WaterLOGSY experiments and Mn(2+)-based paramagnetic probes were also applied to assess their orientations with respect to the SDS micelles. In addition, pulse-field gradient (PFG) diffusion NMR spectroscopy studies were conducted, under different experimental conditions (i.e., concentration, temperature) to characterize the possible changes in the peptides' aggregation states as a putative critical factor for their antimicrobial activity. Finally, molecular dynamics simulations on a variety of conformations showed the intrinsic flexibility of these peptides in both aqueous solutions and membrane-mimetic systems.