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Sodium Dodecyl Sulphate Polyacrylamide Gel Electrophoresis (sodium + dodecyl_sulphate_polyacrylamide_gel_electrophoresis)
Selected AbstractsElectrophoretic patterns of microwaved and ,-irradiated beef liver proteinsJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 10 2001S Farag Abstract The effects of ,-irradiation treatments (2.5, 5 and 10,kGy) and microwaves generated from an oven at low and defrost power settings for 0.5, 1 and 2,min on the total proteins and protein patterns of beef liver immediately after treatment and during frozen storage (,18,°C) for different periods were studied. Chemical analyses indicated that the protein content of beef liver was reduced after exposure to ,-radiation or microwaves and also during frozen storage. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) was used to illustrate the changes in protein bands of different molecular weights and their percentages before and after exposure to gamma and microwave radiation. The main effect of ,-radiation on the protein patterns of beef liver was the disappearance of some high-molecular-weight protein bands and the development of other bands characterised by moderate and low molecular weights. This finding indicates the degradation of beef liver proteins by ,-irradiation. In contrast, microwave treatment caused an increase in the levels of high-molecular-weight protein bands with a concomitant decrease in low-molecular-weight protein bands. This phenomenon demonstrates the polymerisation of low-molecular-weight proteins under the influence of microwaves. © 2001 Society of Chemical Industry [source] A method for the analysis of milk and egg allergens for the atopy patch testEXPERIMENTAL DERMATOLOGY, Issue 10 2009Cinzia Ballabio Abstract:, The patch test with food antigens (atopy patch test, APT) has been reported as a more specific method than prick or RAST for the early detection of cow's milk and/or egg sensitizations in children. Standardization of APT extracts is a major issue on the road towards full clinical exploitation of this assay. Here, we used sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) to characterize sensitivity and specificity of commercial preparations of APT for milk and egg allergies, which are expected to improve the reliability of this test, when compared with fresh food allergen sources. We found that: (i) SDS-PAGE is an appropriate technique for quality control of APT and (ii) commercial milk and egg APT are equivalent to fresh food preparations in terms of allergen content. Clinical trials aimed at characterizing sensitivity and specificity of APT in the diagnosis of food allergy in children will benefit from this technique. [source] Effect of glutenin subfractions on bread-making quality of wheatINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 5 2001Sudesh Jood Five glutenin subfractions (R2,R6) were extracted by sequential centrifugation and addition of sodium chloride, from defatted flours of three wheat cultivars viz. Aubaine (extra-strong), Hereward (strong) and Riband (weak). Seven minutes mixing time was used to carry out fractionation on the basis of depolymerization of glutenin macropolymers (GMP) by using a 2-g Mixograph traces. Depolymerization of GMP occurred at much higher rates in dough of weak cultivars compared with strong and extra-strong cultivars. Protein content was also estimated in GMP (SDS-unextractable) and supernatant (SDS-extractable). Extra-strong cv. Aubaine contained maximum amount of all the glutenin fractions (R2,R6) followed by strong cv. Hereward and weak cv. Riband. Polypeptide compositions of different glutenin fractions were determined by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS,PAGE) under reduced and unreduced conditions, followed by densitometric scanning of stained patterns. The pattern areas of reduced fractions were divided into subareas representative of three main protein classes: high molecular weight (HMW) glutenin subunits; ,-gliadins and a mixture of low molecular (LMW) glutenin subunits and ,, , and ,-gliadins. The amounts of various subunits were proportionate according to the molecular weight of the fractions in each cultivar. The ratio of HMW-glutenin subunits to the LMW-glutenin subunits in each cultivar were found to decrease with the fractionation from R2 to R6. Bread-making quality of three cultivars was also assessed by adding various fractions to a base flour and measuring mixograph peak development time and loaf volume in an optimized baking test. The quality of bread prepared from flour of weak cv. Riband was improved significantly by the addition of HMW fraction (R2) when measured in terms of loaf volume. However, the addition of LMW fraction (R5 + R6) did not cause any appreciable improvement in bread quality over control. On the other hand, addition of HMW fraction (R2) in the flour of good bread wheat cv. Hereward caused adverse effects on the bread-making quality by disturbing the viscoelastic properties. Supplementation of R2 fractions in extra strong wheat cv. Aubaine caused marginal reduction in loaf volume over control. Therefore, the precise proportion present of the two classes of subunit is essential to achieving a proper balance between elastic and viscous properties. [source] Quantification of Greenland halibut serum vitellogenin: a trip from the deep sea to the mass spectrometerRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 7 2009Alejandro M. Cohen This paper focuses on the sequential steps involved in developing a technique for quantifying Greenland halibut vitellogenin, a serum protein biomarker, using a comprehensive mass spectrometric approach. In the first phase of this study, in-gel trypsin digestions of serum proteins separated by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) were analyzed by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). A characteristic band around a molecular mass of 185,kDa, present in the mature female specimens, but absent in the male samples, was identified as vitellognin according to the peptide mass fingerprint obtained by MALDI-MS. Subsequently, MALDI and electrospray ionization tandem mass spectrometry (ESI-MS/MS) analyses were performed on the digest of the vitellogenin band for de novo sequencing. From these studies, a characteristic 'signature' peptide (sequence: FFGQEIAFANIDK) was selected from a list of candidate peptides as a surrogate analytical standard used for quantification purposes. Sample preparation for vitellogenin quantification consisted of a simple one-step overnight trypsin digestion. Samples were spiked with an isotopologue signature peptide standard and analyzed by high-performance liquid chromatography (HPLC) coupled in-line to an electrospray quadrupole-hexapole-quadrupole tandem mass spectrometer, operated in selective reaction monitoring mode. Transitions [(m/z 750.0,,,1020.4 and 750.0,,,1205.4) and (754.8,,,1028.6 and 754.8,,,1213.2)] were monitored for the signature peptide and the internal standard, respectively. Samples obtained from the field showed that vitellogenin levels were in accordance with fish maturity determined by macroscopic examination of the gonad, proving this technique suitable for measuring vitellogenin as a serum protein biomarker for reproductive maturity in female fish. Copyright © 2009 John Wiley & Sons, Ltd. [source] Activity, molecular mass and hydrolysis on baker's yeast protein of extracellular proteases from the putative probiotic bacteria Microbacterium sp. strain 8L and Exiguobacterium mexicanum strain 8NAQUACULTURE RESEARCH, Issue 1 2009César Orozco-Medina Abstract The bacteria Microbacterium sp. 8L and Exiguobacterium mexicanum 8N are known to improve the culture of Artemia franciscana using baker's yeast as food. Using spectrophotometry, sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE), substrate-SDS-PAGE and pH-stat in vitro -digestibility assays, the activity, molecular mass and hydrolysis on baker's yeast protein of proteases from extracellular polymeric substances (EPS) of the strains 8L and 8N along with the pathogenic strains Microbacterium sp. 8R and Vibrio parahaemolyticus 588 CECT (Vp) were studied. The EPSs of 8L and 8R showed one activity band, on which the serine inhibitor phenylmethylsulphonyl fluoride (PMSF) had no effect. The EPSs of 8N showed four bands; two were unaffected by PMSF, whereas one was affected, and the other was partially affected. The EPSs of Vp showed two bands, one partially inhibited by PMSF. No inhibitory effects from 1-chloro-3-tosylamido-7-amino-2-heptanone (trypsin inhibitor) were observed in the protease bands of the studied bacteria. The EPSs of 8L and 8N showed a similar degree of hydrolysis (pH-stat). The EPSs of 8L had the lowest Dice index of similarity of yeast protein profiles at 1 h of reaction. We conclude that the strain 8L could benefit A. franciscana by providing bacterial proteases for digestion of baker's yeast. [source] | ||||||||||