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Oxidation of lactose with bromine
1Department of Biochemistry, College of Medicine, The University of Iowa, Iowa City, IA 52242, USA.
Carbohydrate Research
|October 6, 2005
Summary
Bromine oxidation of lactose models glycosidic linkage cleavage in complex carbohydrates. This study identified various carboxylic acids, confirming significant cleavage of the galactosidic bond in oligosaccharides.
Area of Science:
- Carbohydrate Chemistry
- Analytical Chemistry
- Biochemistry
Background:
- Oligosaccharides and polysaccharides contain glycosidic linkages susceptible to cleavage during oxidation.
- Understanding these cleavage mechanisms is crucial for analyzing complex carbohydrate structures.
Purpose of the Study:
- To investigate glycosidic linkage cleavage during carbohydrate oxidation using lactose as a model.
- To identify and quantify the oxidation products formed.
Main Methods:
- Oxidation of lactose using bromine in a buffered aqueous solution.
- Reduction of oxidation products with sodium borodeuteride.
- Characterization using Gas-Liquid Chromatography-Mass Spectrometry (GLC-MS) of per-O-methyl or per-O-Me3Si derivatives.
- Fractionation using BioGel P-2 column chromatography.
Main Results:
- Lactobionic acid was the major oxidation product.
- Minor products included various carboxylic acids such as oxalic, glyceric, tartaric, and aldonic acids.
- Detection of 1-deuteriogalactitol confirmed galactosidic bond cleavage.
- Galactosylarabinonic acid was the major minor product (7.5%), with other minor products ranging from 0.2-3.7%.
Conclusions:
- Bromine oxidation of lactose effectively cleaves the galactosidic linkage.
- The identified products support the mechanism of glycosidic bond cleavage during carbohydrate oxidation.
- These findings are relevant to understanding the degradation of larger polysaccharides.
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