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- Karlsson, Camilla A-C, et al.
(författare)
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Detergent Induced Removal of b-Lactoglobulin from Stainless Steel Surfaces at Influenced by Surface Pretreatment
- 1999
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Ingår i: Journal of Colloid and Interface Science. - : Elsevier BV. - 1095-7103 .- 0021-9797. ; 220, s. 471-473
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Tidskriftsartikel (refereegranskat)abstract
- The adsorption of β-lactoglobulin to stainless steel and its subsequent removal were followed using in situ null ellipsometry. The influence of the surface pretreatment on the protein removal by the surfactant SDS and by sodium hydroxide was studied. All surfaces were precleaned in strongly alkaline solution. Some surfaces received no further pretreatment, while others were either passivated in nitric acid or plasma-cleaned prior to experiments. Stainless steel surfaces subjected to different surface pretreatments showed considerable differences in cleaning behavior. Cleaning, using NaOH, of surfaces which had been precleaned with alkali only or with plasma resulted in practically complete β-lactoglobulin removal. In contrast, appreciable amounts of protein remained on passivated stainless steel. Protein removal by SDS was limited and comparable for all three surface pretreatments investigated. Only minor effects on the protein adsorption tendency were observed. The amounts of β-lactoglobulin adsorbed tended to be somewhat lower on the passivated surfaces.
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| 2. |
- Karlsson, Camilla A-C, et al.
(författare)
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Some surface-related aspects of the cleaning of new and reused stainless-steel surfaces fouled by protein
- 1998
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Ingår i: International Dairy Journal. - 0958-6946. ; 8:10, s. 925-933
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Tidskriftsartikel (refereegranskat)abstract
- The adsorption of β-lactoglobulin to stainless steel and its subsequent alkali-induced removal were followed using ellipsometry. New steel samples differing in bulk composition, surface finish or chemical pretreatment were used. All surfaces were precleaned in strongly alkaline solution, and some were subsequently passivated in nitric acid. Furthermore, on surfaces differing in pretreatment measurements were performed during repeated fouling and cleaning cycles. No correlation was found between the bulk composition or the surface finish and the fouling tendency or the cleanability. However, striking differences in cleanability between stainless-steel surfaces subjected to different chemical pretreatments were evident, particularly at low temperature. Still, only minor effects on the fouling tendency were observed. When subjecting surfaces to repeated fouling and cleaning without renewed pretreatment, the differences in cleaning performance decreased but were still significant. While the cleanability of non-passivated surfaces appeared to decrease somewhat when reused, changes seemed smaller for passivated surfaces.
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| 3. |
- Karlsson, Camilla A-C, et al.
(författare)
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Time and temperature aspects of β-lactoglobulin removal from methylated silica surfaces by sodium dodecyl sulphate
- 1996
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Ingår i: Colloids and Surfaces B: Biointerfaces. - : Elsevier BV. - 0927-7765. ; 6:4, s. 317-328
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Tidskriftsartikel (refereegranskat)abstract
- The adsorption of β-lactoglobulin onto methylated silica surfaces and the subsequent protein removal by the anionic surfactant sodium dodecyl sulphate (SDS) were followed using in-situ ellipsometry. Experiments were performed at pH 6.0 in phosphate-buffered saline solution. Parameters varied include temperature, length of time for protein adsorption from solution and surface residence time of β-lactoglobulin. The temperature was kept constant throughout a trial, and the majority of experiments were carried out at a few degrees below the protein denaturation temperature as reported from differential scanning calorimetry studies. β-Lactoglobulin adsorption at high temperatures resulted in aggregation at the surface after a lag phase of several minutes. Varying the protein adsorption time and thus the amount adsorbed while keeping the protein surface residence time fixed did not seem to affect the amount desorbed upon rinsing or the amount eluted by surfactant. For short β-lactoglobulin adsorption times, the adsorbed amounts were comparable at all temperatures studied. The temperature hardly affected the amount desorbed during rinsing, but did however have a pronounced influence on the protein removed by surfactant. Up to around 60°C practically all β-lactoglobulin was eluted by the SDS. The fraction removed then decreased with temperature, with a sharp drop between 70 and 73°C, and a further decline at higher levels. SDS was seen to be highly inefficient at removing β-lactoglobulin adsorbed at temperatures above 70°C. The trend observed is attributed to temperature-dependent changes in the protein resident on the surface. The β-lactoglobulin surface residence time was seen to significantly affect the elutability. At short residence times the removal efficiency was comparably high, but decreased with time. However, no significant difference could be detected between two sufficiently long residence times. The behaviour is consistent with the assumption of multiple states of adsorbed proteins, together with slow conformational changes in the adsorbed protein layer.
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| 4. |
- Karlsson, Camilla A-C, et al.
(författare)
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β-Lactoglobulin fouling and its removal upon rinsing and by SDS as influenced by surface characteristics, temperature and adsorption time
- 1996
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Ingår i: Journal of Food Engineering. - 0260-8774. ; 30:1-2, s. 43-60
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Tidskriftsartikel (refereegranskat)abstract
- The extensive fouling common in the food industry puts high demands on equipment cleaning. The adsorption of β-lactoglobulin and its removal by the anionic surfactant sodium dodecyl sulphate (SDS) were followed at pH 6.0 using in situ ellipsometry. Hydrophilic chromium oxide and stainless steel together with hydrophobic methylated silica were studied at different temperatures. Differences between chromium oxide and steel were small, while hydrophobic silica showed significantly different initial adsorption kinetics and adsorbed amounts. Also, the temperature-dependence of the amount desorbed upon rinsing as well as of the overall cleanability differed greatly. At around the β-lactoglobulin denaturation temperature, multilayer build-up at the surface was seen, and the cleanability was very low. Of two protein adsorption times employed, the longer resulted, for metal oxide surfaces, in less desorption during rinsing.
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| 6. |
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| 8. |
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| 9. |
- Lorber, Christian, et al.
(författare)
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Synthesis, Structures and Oxo Transfer Reactivity of bis(Dithiolene) Tungsten(IV,VI) Complexes Related to the Active Sites of Tungstoenzymes
- 1998
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 1520-5126 .- 0002-7863. ; 120:32, s. 8102-8112
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Tidskriftsartikel (refereegranskat)abstract
- A series of bis(dithiolene)tungsten(IV,VI) complexes derived from benzene-1,2-dithiolate (bdt) has been prepared as an synthetic approach to pterin dithiolene-bound active sites of tungstoenzymes, one example of which, a archaeal oxidoreductase, has been established crystallographically (Chan et al. Science 1995, 267, 1463). With [WIVO(bdt)2]2- (2) as the starting compound, silylation with RR'2SiCl afforded [WIV(bdt)2(OSiRR'2)]1- (4). Oxidation of 4 with Me3NO gave [WVIO(bdt)2(OSiRR'2)]1- (5), also accessible by silylation of [WVIO2(bdt)2]2- (3). Reaction of 3 or 5 with Me3SiCl resulted in [WVIO(bdt)2Cl]1- (6), from which the unstable species [WVIO(bdt)2L]1- (L = ButO-, PhS-) were generated in solution. Reductive oxo transfer of 6 with L' = P(OEt)3 or ButNC/P(OEt)3 gave [WIV(bdt)2L'2] (8 and 9). Sulfido complex [WVIS(bdt)2(OSiRR'2)]1- (12) was obtained in the reaction systems 4/(PhCH2S)2S and 5/(Me3Si)2S. Structures of [WO(SPh)4]1- and [W(bdt)3]2- and eight complexes of types 4-6, 8, 9, and 12 were determined by X-ray crystallography. Complexes 4 and 5 are tungsten analogues of the desoxo Mo(IV) and monooxo Mo(VI) states of Rhodobacter sphaeroides DMSO reductase. Six types of reactivity, including oxygen atom transfer, are recognized by the synthesis and interconversion of the set of complexes. The potential biological relevance of these complexes to the structure and function of active sites in two families of tungstoenzymes is considered (RR'2 = Me3 (4); ButMe2 (4 and 5), ButPh2 (4, 5, and 12)).
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| 10. |
- Sikut, R, et al.
(författare)
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Detection of CD43 (leukosialin) in colon adenoma and adenocarcinoma by novel monoclonal antibodies against its intracellular domain.
- 1999
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Ingår i: International journal of cancer. Journal international du cancer. - 0020-7136. ; 82:1, s. 52-8
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Tidskriftsartikel (refereegranskat)abstract
- CD43 is a leukocyte-associated sialoglycoprotein which is also expressed in human colon adenoma and carcinoma. To obtain monoclonal antibodies (MAbs) that would react with CD43 in a glycosylation-independent way, antibodies were raised against a peptide corresponding to a portion of the CD43 cytoplasmic domain. Hybridomas were screened on paraffin sections from CD43-positive colon tumours. The reactivity of the antibodies with CD43 was verified by Western blot analysis of lysate of CHO cells transfected with human CD43 cDNA and by immunoprecipitation of lysates from CD43+ cell lines. Epitope mapping of antibodies was done using overlapping heptameric peptides. A detailed characterisation of one of the novel antibodies (CD43-3A1) is presented. This antibody reacts with the CD43 protein regardless of its glycosylation in Western blot analysis, immunoprecipitation and immuno-histochemistry of paraffin sections. Immuno-histochemical analysis of paraffin sections from colon adenoma and carcinoma tissues as well as colon cancer cell lines revealed that CD43 was predominantly localised intracellularly, in contrast to leukocyte-type cells. The MAb reacted more efficiently with paraffin-embedded colon adenoma and carcinoma cells than previously characterised CD43-specific antibodies. This should facilitate the evaluation of a potential role of CD43 during cancer development.
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