A Multienzyme Complex for De Novo Purine Biosynthesis
Multienzyme complexes are defined as aggregates of different functionally related enzymes integrated into highly organized structures by non-covalent bonds. Such a structural arrangement is considered to confer a catalytic advantage in that an unstable intermediate may be transferred more efficiently from one active site to the next. A number of such complexes have been isolated in association with subcellular organelles or membranes. Examples of these include the glycogen phosphorylase particles of mammalian muscle and the cytochrome electron transport system of mitochondrial membranes. More significantly the cytosol of a wide variety of cell types has been shown to contain enzyme complexes e.g. the glutamine synthetase and the fatty acid synthetase complexes. Recent evidence would suggest however, that in some species the latter complex is, in fact, a single multifunctional polypeptide chain (1).
KeywordsAmide Pyruvate Glutamine Folate Cytosol
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