Department of Biochemistry
4-403 BSB
Iowa City, IA 52242-1109 USA phone: 877-846-8569
or 319-335-7932
fax: (319) 335-9570
biochem@uiowa.edu
Department of Biochemistry
Faculty Profiles
Rex Montgomery, Ph.D
Professor Emeritus
Current Research
It is becoming increasingly recognized that the carbohydrate groups in glycoproteins and glycolipids can play important roles in biological functions, such as cellular transport processes, communication and defense mechanisms. Frequently the carbohydrate groups are small components of the molecule and their structures are polydisperse and microheterogeneous. The isolation of these molecules from biological systems in pure form is difficult, limited in many instances to gel electrophoresis or microchromatographic techniques. Commensurate with these technologies, the structural elucidation of the carbohydrate groups, preparative to structure-function studies, must be possible at picomole levels, such as would be obtainable from gel electrophoresis bands.
The degrees of structural detail would involve an evaluation of molecular purity, compositional analysis, mapping of the oligosaccharide microheterogeneity, linkage analyses and exoglycosidase-assisted sequencing and conformational analysis. Such studies combine the technologies of chromatography, spectrometry (such as UV/IR, NMR, GC/MS, FABS), mass spectrometry, microanalysis, microchemistry, and enzymology.
Examples of the application of these structure-function analyses include:
- Extracellular microbial polysaccharides. The polysaccharides of species of the phytopathogen Erwinia chrysanthemi have been shown to be polyrhamnoglucuronoglucomannans with the exception so far of one case that is a polyfucoglucuronoglucogalactan. The pathogenicity of each of these species is different and may reflect in part the extracellular polysaccharide.
- Peroxidases. The peroxidases of horseradish and soybean are glycoproteins, the several carbohydrate groups of which are distributed along the polypeptide chain. Studies are in progress to determine the relationship of these glycan groups to the enzymatic activity.
- Lipopolysaccharides. Each of the several types of Legionella pneumophila has a specific membrane-bound antigen, the characterizations of which are important to the diagnosis of Legionnaires' disease. The structural aspects of each serotype antigen are being elucidated. Upon gel electrophoresis the lipopolysaccharides form a "ladder" of components and the relationship of each "rung" of the ladder to another rung is unknown. The microanalytical techniques are being applied to the study of lipopolysaccharides.
- Microanalyses. The microanalytical techniques have been applied to the analysis of inositol phosphates in corn, the lipophilic compounds in fermentation byproducts and the process of corn steeping.
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