Analyses of N-linked oligosaccharides using a two-dimensional mapping technique

We propose a two-dimensional sugar map method for the simple, reproducible, and sensitive analysis of the structures of N-linked oligosaccharides. The structure of an unknown oligosaccharide can be characterized from its position on the map. The data base for the sugar map is prepared by the use of 113 kinds of standard oligosaccharides, 58 of whose structures have been confirmed by 1H NMR spectroscopy. The present method involves six steps, (i) preparation of oligosaccharides from glycopeptides by N-oligosaccharide glycopeptidase (almond) digestion, (ii) derivatization of the reducing ends of oligosaccharides with a fluorescent reagent, 2-amino-pyridine, by using sodium cyanoborohydride, (iii) separation of oligosaccharide derivatives by high-performance liquid chromatography with an ODS-silica column, (iv) analysis of the size of each separated oligosaccharide on an amide-silica column, (v) plotting of the elution position of a sample on the two-dimensional sugar map obtained for the standard oligosaccharides, and (vi) structural analysis of the oligosaccharides by a combination of sequential exoglycosidase digestion and the steps (iii-v). The present method was applied to the identification of the structures of oligosaccharides in hen ovalbumin. It was found that two unusual oligosaccharides that have not yet been reported exist in ovalbumin.     

Stabilization of configurational states and enzyme activities in subcellular fractions after fixation with extremely low concentrations of glutaraldehyde

Synopsis The activities of various enzymes in some subcellular organelle fractions were examined after fixation in glutaraldehyde of various concentrations. A high speed centrifuge was used to shorten the fixation time.At the lowest concentration (0.01%) glutaraldehyde stabilized instable configurational states of mitochondria as revealed by electron microscopy. In addition, at this concentration, at least 70% of the original monamine oxidase, ATPase and cytochrome oxidase activities were preserved. The activity of acid phosphatase, on the other hand, was enhanced in a lysosomal fraction when fixed with the aldehyde at higher concentrations, e.g. 0.1% and 1.0%. It is possible that the aldehyde at higher concentrations has the same effects on the lysosomal membrane as freeze-thawing. Glucose-6-phosphatase activity was well-preserved in a microsomal fraction fixed with 0.01% glutaraldehyde but was decreased drastically when the concentration of the aldehyde was greater than 0.05%.     

Reduction of Isoprothiolane Sulfoxide in Rats

Isoprothiolane sulfoxide, an oxidative metabolite of isoprothiolane, was reduced to isoprothiolane in living rats and in an in vitro system containing rat liver supernatant. No stimulatory effect of a flavin cofactor (FAD) was observed on the sulfoxide reduction in vitro.