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Rozbudowana struktura drugo- i trzeciorzędowa białek serwatkowych: α-la, β-lg, BSA i immunoglobulin, sprawia, że są podatne na procesy denaturacyjne wywoływane czynnikami chemicznymi lub fizycznymi (temperatura czy wysokie ciśnienia). Procesy termiczne, szeroko stosowane w przemyśle mleczarskim, powodują denaturację, zmianę właściwości fizyko-chemicznych i żywieniowych białek serwatkowych. Poznanie tych zmian i technik, którymi można je obserwować jest istotne ze względów badawczych i żywieniowych. W artykule przedstawiono przegląd kilku technik wykorzystujących zmianę właściwości immunore-aktywnych, termodynamicznych (temperatura i entalpia denaturacji, energia aktywacji), fizykochemicznych pozwalających lepiej poznać proces denaturacji tych białek.
Wyróżniamy dwa rodzaje przeciwciał: monoklonalne (Mab; mają zdolność swoistego rozpoznawania pojedynczego determinantu antygenu) i poliklonalne (charakteryzują się zdolnością reagowania z wieloma epitopami antygenu). Specyfika oddziaływań pomiędzy antygenem a przeciwciałem sprawia, że przeciwciała monoklonalne znajdują coraz szersze zastosowanie w analizie laboratoryjnej w medycynie, w badaniach żywności i in. Produkcja przeciwciał monoklonalnych obejmuje szereg następujących po sobie etapów: 1-wybór antygenu, 2-wybór myszy i linii komórkowej, 3-immunizacja, 4-fuzja komórek i selekcja hybryd produkujących Mab skierowane swoiście do antygenu, 5-produkcję przeciwciał monoklonalnych in vitro, na dużą skalę, 6-oczyszczenie.
Activity and immunoreactivity of lipase, activity of lipoxygenase, acid and peroxide values were determined during the storage of rapeseed with 6, 10, 14, and 18% moisture content. The most intensive changes in lipase activity were observed during storage of rapeseed with 10% moisture content and ranged from 18.73 to 55.85 A.U./mg protein as compared to stored rapeseed with 6, 14, and 18% moisture content. During the storage there were also observed changes in lipase immunoreactivity, lipoxygenase activity, acid and peroxide values, however none of the relationships between enzymes and quality of rapeseed lipids was found to be statistically significant and therefore it can be concluded that the processes taking place during storage of rapeseed with varied moisture content show complexity and the enzymes examined in the experiment can appear to be not only factors affecting the quality of the lipid fraction.
The influence of the non-enzymatic glycosylation (glycation) of guanosine-5’-triphosphate (GTP) by glucose on its physicochemical properties was investigated. The progress of glycation was monitored by the ionic-exchange chromatography. The results of analysis of the glycated mixture enabled identifying its three components: free GTP, glycated GTP and GTP-glycated complex. These results were also confirmed by spectral analysis and thin layer chromatography. Moreover, it was suggested that the glycation of nucleic acids could change their nutritive value, e.g. immunogenic and allergic potential.
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Characteristics of lipolytic enzymes of rapeseeds

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Some properties of lipolytic enzymes of a microsomal fraction of two Polish varieties of rapeseed were qualified. Enzymes extracts were prepared front germinated rapeseeds of two varieties: double improved - Bolko and high erucic - Skrzeszowicki. The lipase was purified by ultracentifuge. The obtained supernatant was used to chracterise the lipase and further to purify by a column chromatography method, using the following carriers: Sephadex G-100, Sephacryl S-300, DEAE sephadex A-50 and Q Sepharose. Examined enzymatic extracts showed two optima of lipolytic activity: pH 7.5 and pH 9.0. The highest degree of hydrolysis of tributyrylglicerol (TC 4 : 0) revealed lipases of the Bolko variety seeds at 30°C, and lipases of the Skrzeszowicki seeds at 40°C. At the temperature 30 - 40°C lipases maintained approx. 89 % to 93 % of their maximum activity. However, at 25°C and 50°C their activity was reduced to approx 20 %. When the temperature was above 40°C, thermal inactivation of lipolytic enzymes from two varieties progressed in two stages. Examined lipases maintained 20 % to 30 % of their initial activity, after storing them for 1 h at 60°C. During the purification of lipases, carried out by a column chromatography method, the most favourable results were obtained using molecular filtration on Sephadex G-100 gel.
The activity of triacylohydrolases of rapeseed varieties and phylums available in Poland: Bolko, Ceres, Liporta, Mar-3 was estimated. The variable factors were the moisture of seeds, the level of mechanical damage (micro and macro) resulting from the method of harvest and the type of dessicants used in the final stage of seed ripening. A clear (statistically highly significant) diversification of the activity of lipolytic enzymes was found. It related to the varieties and experimental groups of the different methods of harvest (one- and two-stage harvest) and the moisture of seeds. The maturity degree, the kind and amount of the ripening regulator applied in the final stage of vegetation, differentiated the activity of lipolytic enzymes in a highly significant way.
The aim of this work was to use the conductometry method for the differentiation of the chemically- and enzymatically-modified food proteins. The protein extracts of soybean, bean pea, maize and rice seeds, 3 varieties “Tonacja”, “Nawra” and “Sukces” of wheat, as well bovine serum albumin, pepsin trypsin and acid protein hydrolyzates were investigated. Additionally, proteins were glycated by glucose. It was found that differences of the electrolytic conductivity between native proteins and their hydrolyzates were statistically significant; the electrolytic conductivity of the water protein solutions was directly proportional to the concentration of protein. It was also proved that the concentration of glucose in the protein solution modified its electrolytic conductivity. Moreover, statistically significant differences were observed between native and glycated proteins. Finally, it was stated that the electrolytic conductivity can be a tool for the differentiation of the native and modified proteins.
The aim of this study was to investigate the effect of non-enzymatic glycosylation and hydrolysis of pea albumins with pepsin on their immunoreactive properties. Albumin fraction was isolated from pea seeds an then glycated and hydrolysed by pepsin. Pea albumin was characterised by SDS‑PAGE and glycotest. A 15% progress in non-enzymatic glycosylation was found. The in vivo experiment demonstrated the influence of glycation on mouse mucosal immune system. The influence of native, glycated and hydrolysed pea albumins on spleen (SPL) and mesenteric lymph nodes (MLN) lymphocytes proliferation was investigated. The culture MLN lymphocytes showed an increase in proliferation during stimulation with all of antigens (native, glycated, hydrolyzed). The proliferation was higher in MLN lymphocyte of the intraperitoneally-sensitized group. This observation suggests that the route of immunization can affect their immunoreactivity. SPL lymphocytes of the orally-immunized group showed higher proliferation as compared with SPL lymphocytes of the group sensitized before oral immunization. It is likely that the route of antigen administration has induced a specific food tolerance. The results suggest that none of the modifications performed has changed the immunoreactivity of the investigated proteins to a great extent.
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