啤酒酵母蛋白酶解物分子量分布研究初探

凝胶层析分离经胰蛋白酶酶解啤酒酵母后得到的多肽粗粉,并采用SDS-PAGE电泳测定啤酒酵母多肽分子量,发现其中含有16～26、5、1.4kDa等三种不同分子量水平的蛋白组分,酶解得率分别为27.08%、11.55%、17.99%.     

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.     

Disintegration of Northern Cape iron ores under reducing conditions

Abstract

Cracking occurs in the first step of gaseous reduction of hematite iron ore, to magnetite, and can lead to the formation of fine material, with deleterious effects on operation of shaft furnaces. To study this, samples of three ore types from the Northern Cape iron ore field in South Africa, and one blended ore from this region, were studied. The methods were high temperature microscopy (during reduction) and quantification of fines formation following reduction disintegration tests. The ore types do differ significantly with regards to their propensity to form fines. Although disintegration is clearly triggered by reduction, no direct correlation could be established between the degree of reduction and the amount of fines generated. Reduction disintegration increased with higher hydrogen percentages (>5%) in the reduction gas, and at higher temperatures (in the 500–700°C range). Disintegration of the samples decreased at temperatures >750°C. There was no correlation between the presence of gangue minerals and fines formation.     

Applications for plasma transferred arc welded tools during hot steel tube making

Abstract

This paper describes applications of a tool reinforcement technology, using plasma transferred arc (PTA) welding, in hot metal rolling. The coating of large NbC particles shows a remarkable performance in the suppression of galling. As the rolling temperature increases, a matrix material with high temperature resistance to deformation is recommended. The tool life is slightly longer when a thick scale layer exists on the hot metal surface, but when the scale is eliminated the new tool demonstrates excellent capability. The new tool also shows a higher level of performance when rolling hot titanium and hot stainless steel. The application philosophy of PTA welded tools is demonstrated.     

减轻自然灾害,为人类造福——写在“国际减轻自然灾害十年”之始

本文阐述了”国际减轻自然灾害十年”的来历和宗旨;我国和世界的灾害;减轻灾害以“预防为主”的方针以及建立和发展灾害工程学.     

玉米蛋白PAGE法鉴定玉米品种及纯度

本文比较了国内外应用的玉米品种及纯度鉴定的方法。玉米蛋白质聚丙烯酰胺凝胶电泳法(PAGE)具有准确、快速、经济、易于普及等优点,是目前国内外最先进的玉米品种及纯度鉴定技术。     

Isolation and characterization of pepsin‐solubilized collagen from the integument of sea cucumber (Stichopus vastus)

BACKGROUND: Sea cucumber (Stichopus vastus) is considered an underutilized resource, since only its stomach and intestines are eaten raw as salad in a few countries and the remaining parts, especially the integument rich in collagen, is discarded. Hence a valuable by‐product having potential nutraceutical and pharmaceutical applications is wasted. In the present investigation, pepsin‐solubilized collagen (PSC) from the integument of S. vastus was isolated, purified and characterized. RESULTS: Sodium dodecyl sulfate–polyacrylamide gel electrophoretic analysis showed that the purified collagen was of type I, consisting of three α1 chains of approximately 122 kDa each. The peptide map of PSC digested by V8 protease was different from that of calf skin type I collagen. Fourier transform infrared spectroscopy revealed that the triple helical structure was well preserved in isolated collagen. The denaturation temperature of PSC was 21.23 °C and showed good gel‐forming capability at pH 6.5 and 300 mmol L^?1 NaCl. CONCLUSION: It is inferred that the collagen isolated from S. vastus integument has potential for use as an alternative to land‐based mammalian collagen in food, nutraceuticals and pharmaceutical industries. © 2012 Society of Chemical Industry     

Differentiation of lactococci from 2 Greek cheeses with protected designation of origin by phenotypic criteria and RAPD-PCR

Abstract: Seventy‐six lactococci isolates from 2 protected designation of origin (PDO) cheeses were studied for their acidification ability, proteolytic activity, and inhibitory activities as well as their intraspecies characterization by randomly amplified polymorphic DNA‐polymerase chain reaction (RAPD‐PCR). Fifty‐two of them were characterized as Lactococcus lactis subsp. lactis by the SDS‐PAGE of whole‐cell proteins. The test strains increased the amount of acid in milk from 6 to 24 h as well as the quantities of amino acids on incubation for 4 d. The majority of the isolates degraded preferentially α_s‐casein. The isolates from Feta differed from those of Graviera Kritis in respect of β‐casein degradation. This fragment was either not degraded or underwent a small degradation by lactococci from Feta. A stronger intensity of acidification for the isolates from Feta and a higher casein breakdown ability for those from Graviera Kritis were also recorded. Lactococci from Feta and Graviera Kritis inhibited, preferentially, the growth of Escherichia coli O157:H7, and Yersinia enterocolitica, respectively. A high heterogeneity among the isolates according to RAPD‐PCR was determined, as well as grouping of the isolates according to their source of isolation. Selected isolates from each cheese could be used as starters to make either Feta or Graviera Kritis.