Amylose: structure synthesis

These synthetic linear and branched molecules may be important as type polymers, particularly if the interconversion of amylose to amylopectin is intramolecular, in which case the initial molecular weight and molecular-weight distribution would be retained. There is the possibility that the in vitro synthesis may even result in a truly three-dimensional structure, as distinct from that of the natural component. 

The strict primer dependence of the glycogen phosphorylases makes them ideal candidates for the synthesis of hybrid structures of amylose with non-natural materials... 

This ehapter eonsiders the reeent view on moleeular structures of the amylose and amylopectin components in potato and how they are organized to form characteristie structures inside the stareh granules. The phosphorylation of starch, and the synthesis of its eomponents in normal and genetieally modified potatoes, is also discussed. 

This subject has been of continuing interest for several reasons. First, the present concepts of the chemical constitution of such important biopolymers as cellulose, amylose, and chitin can be confirmed by their adequate chemical synthesis. Second, synthetic polysaccharides of defined structure can be used to study the action pattern of enzymes, the induction and reaction of antibodies, and the effect of structure on biological activity in the interaction of proteins, nucleic acids, and lipides with polyhydroxylic macromolecules. Third, it is anticipated that synthetic polysaccharides of known structure and molecular size will provide ideal systems for the correlation of chemical and physical properties with chemical constitution and macromolecular conformation. Finally, synthetic polysaccharides and their derivatives should furnish a large variety of potentially useful materials whose properties can be widely varied these substances may find new applications in biology, medicine, and industry. 

Delrue, B., Fontaine, T., Routier, F., Decq. A., Wieruszeski, J.-M., Van Den Koomhuyse, N., Maddelein, M.-L., Fournet, B., and Ball, S. 1992. Waxy Chlamydomonas reinhardtii Monocellular algal mutants defective in amylose synthesis and granule-bound starch synthase activity accumulate a structurally modified amylopectin. J. BacterioL 174,3612-3620. 

The synthetic ( )-calanolide A was resolved into its enantiomers, (+)-calanolide A (1) and ( )-calanolide A, by using a semipreparative chiral HPLC column packed with amylose carbamate eluting with hexane/ethnol (95 5). The ultraviolet detection was set at a wavelength of 254 nm. (+)-calanolide A and its enantiomer (—)-calanohde A were collected, and their chemical structures were identified based on their optical rotations and spectroscopic data, as compared with the corresponding natural and synthesis compounds. 

Other than the early studies on the determination of unit-cell parameters, little work has been done on the determination of structure of the different crystal forms of amylose. The major reason for this is the nature of the material itself namely, its powdery character. Following additional developments in the preparation of amylose, the discovery of its film-forming ability, and the synthesis of film-forming derivatives of amylose (such as the triacetate), some new structural studies were attempted, on which some comments will now be made. 

Fig. 5.—Proposed Synthesis of Amylopectin from Glycogen. [The diagram shows mainly the removal of A-ohains if B-ohains are removed, these are presumably further attacked, otherwise an amylose with a branched structure would be formed during the subsequent combination of debranched chains.] (Key As in Fig. 1, and P- represents a phosphate group.)...

The strict primer dependence of the glycogen phosphorylases makes them ideal candidates for the synthesis of hybrid structures of amylose with non-natural materials (e.g., inorganic particles and surfaces, synthetic polymers). For this, a primer functionality (maltooligosaccharide) can be coupled to a synthetic structure and subsequently elongated by enzymatic polymerization resulting in amylose blocks. 

Amylose synthesis depends on the concentration of ADP-Glc, as GBSSI has a high for the substrate as compared to the soluble starch synthases. The phosphoglucomutase (PGM)-deficient mutants do make starch but are deficient in amylose, even though GBSS is present. The PGM-deficient mutants can make amylopectin but not amylose as shown by detailed structure studies of the starch accumulated by the algal... 

---