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This is a story of a choice of plant material as well as the choice of a specific protein. Subsequently, the structure of the protein and its three different sub-units were studied. The role of these subunits in the enzyme, were explored, as well as the role of the enzyme for plant metabolism. Where-ever possible connections with other similar molecules, inclusive in animals, were mentioned. Special emphasis is placed on the various forms and composition of the glycan chains of the major isozyme.

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Robert B. van Huystee - Department of Biology, The University of Western Ontario, London, Ontario, N6A 5B7, Canada.

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