Vergleichende Untersuchungen der trypsinspezifischen reaktiven Zentren verschiedener Phaseolus coccineus- und Phaseolus vulgaris-Inhibitoren

Zusammenfassung Drei Trypsin-Chymotrypsin-Inhibitoren aus den Samen von Feuerbohnen (Phaseolus coccineus L.) PCI 3, 4₂ und 5 und drei Inhibitoren aus den Samen von Buschbohnen (Phaseolus vulgaris var. nanus) PVI 3, 4 und 5 enthalten im reaktiven Zentrum gegen Trypsin einen Lysin-Rest. Ein Inhibitor ausPhaseolus coccineus, PCI 2, enthält dort einen Arginin-Rest. Alle sieben untersuchtenPhaseolus-Inhibitoren sinddouble headed.

---

Comparative studies on the reactive sites against trypsin of some inhibitors from Phaseolus coccineus and Phaseolus vulgaris

Summary Three of the trypsin chymotrypsin inhibitors from the seeds of runner beans (Phaseolus coccineus L.), PCI 3, 4₂, and 5, and three of the inhibitors from the seeds of french beans (Phaseolus vulgaris var. nanus), PVI 3, 4, and 5, contain a lysine residue in the reactive site against trypsin. One of the inhibitors fromPhaseolus coccineus, PCI 2, contains an arginine residue there. All sevenPhaseolus inhibitors investigated are double headed.

---

---

Die Arbeiten wurden durch die AIF über den Forschungskreis der Ernährungsindustrie gefördert     

Automated Karl Fischer titration for liquid samples – Water determination in edible oils

In the field of food analysis, rapid measurements and results are generally of high importance. The Karl Fischer titration (KFT), a chemical method for determining water content, and its automated performance enhance rapidity by giving the opportunity to deal with more samples in less time; automated sequences can include different determination methods and sample treatments. Moreover, automation can improve reproducibility and precision.     

Water determination – Scientific and economic dimensions

Water content is for a number of reasons one of the most important properties of foodstuffs. The determination of water content is therefore a very important analysis. This is not only the case for scientific or technical reasons. The water fraction in food is sometimes regarded as a component without commercial value. The price is based on dry matter, which makes water content determination an analysis with economic consequences. Different existing methods often yield different results. This entrains the problem that vendor and buyer, for economic reasons, prefer different methods to favour their role in trade. The situation would be easier if the method to be applied would be the same and would be agreed upon by both parties. International standards and reference methods are established by bodies that consist not only of neutral scientists but also of representatives of industry. These will usually see the interest of their respective company and will rather try to introduce methods which “improve” their profit rather than accepting methods scientifically correct but with lower profit. Milk powder trade is given as an example to illustrate such a situation.     

Microsatellite instability analysis: a multicenter study for reliability and quality control

The molecular biology section of the Hereditary Non-Polyposis Colorectal Cancer study group-Germany, instituted a multicenter study to test the reliability and quality of microsatellite instability (MSI) analysis. Eight laboratories compared MSI analyses performed on 10 matched pairs of normal and tumor DNA from patients with colorectal carcinomas. A variety of techniques were applied to the detection of microsatellite changes: (a) silver and ethidium bromide staining of polyacrylamide gels; (b) radioactive labeling; and (c) automated fluorescence detection. The identification of highly unstable tumors and tumors without MSI was achieved in high concordance. However, the interpretation of the band patterns resulted in divergent classifications at several microsatellite marker loci for a large fraction of this tumor/normal panel. The data on more than 30 primers per case suggest that the enlargement of the microsatellite panel to more than 10 loci does not influence the results. In this study, cases with MSI in less than 10% of loci were classified as microsatellite stable, whereas MSI was diagnosed in cases with more than 40% of all markers unstable. We propose that a panel of five microsatellite loci consisting of repeats with different lengths should be analyzed in an initial analysis. When less than two marker loci display shifts in the microsatellite bands from tumor DNA, the panel should be enlarged to include an additional set of five marker loci. The number of marker loci analyzed as well as the number of unstable marker loci found should always be identified. These criteria should result in reports of MSI that are more comparable between studies.     

Crystallization and microstructural evolution of MgO–Al<Subscript>2</Subscript>O<Subscript>3</Subscript>–SiO<Subscript>2</Subscript>–TiO<Subscript>2</Subscript>–La<Subscript>2</Subscript>O<Subscript>3</Subscript> glass-ceramics

Crystallization and microstructure of glasses with the molar compositions 1MgO·1.2Al₂O₃·2.8SiO₂·1.2TiO₂·xLa₂O₃ (x = 0.1 and 0.4) were thermally treated at different temperatures in the range from 950 to 1250 °C and then analyzed by X-ray diffraction and scanning electron microscopy, in combination with energy-dispersive X-ray spectroscopy and electron backscatter diffraction. It was found that the microstructure is first homogeneous with the precipitation of randomly distributed crystals and then indialite domains with embedded perrierite and rutile crystals are formed. For higher temperatures or prolonged times, more domains appear and expand into the bulk of the sample. Finally, the entire sample consists of the indialite domains and the boundaries that are enriched in rutile, perrierite, and magnesium aluminotitanate. Nevertheless, very distinct differences are observed between the samples with different La₂O₃ concentrations. For the sample with x = 0.4, the domains were detected at lower temperatures, while the quantity and size of the domains increase faster due to the promoted precipitation of indialite. For the sample with x = 0.1, in addition to the domain boundaries, secondary boundaries between the “regions” (assemblages of the domains) are observed in a larger length scale. The average size of the crystalline phases found between the “regions” is larger than that typically observed at the domain boundaries. The sizes of the crystals at the boundaries decrease with higher concentrations of La₂O₃, and the crystals (especially perrierite) within the domains become larger, resulting in a more homogeneous microstructure. This results in better dielectric properties, i.e., much higher quality factor for the sample with x = 0.4 in comparison to that with x = 0.1 after heat-treatment at 1150 or 1250 °C.