Soluble starch synthases granule bound

Antibody prepared against SSI effectively neutralized souble SSI activity, but had no effect on either the activities of GBSSI or GBSSII, or even on SSII. Alternatively, antibody prepared against the starch granule-bound proteins effectively inhibited GBSSI activity, but had very little effect on the soluble starch synthases.173... 

Amylose is synthesized by granular-bound starch synthase, whereas amylopectin is synthesized by soluble starch synthase (Chapter 4).334,339 Because amylose is synthesized by the granular-bound starch synthase in a progressive manner,340 the amylose molecule is likely confined in the granule and has little opportunity to interact and form double helices with other starch molecules to facilitate branch formation. Branching reactions do occur on some amylose molecules, but at a much lower frequency than with amylopectin, and result in slightly branched amylose molecules. 

Maddelein, M.-L., Bellanger, F., Deirue, B., Libessart, N., D hulst, C., Van den Koomhuyse, N., Fontaine, T Wieruszeski, J.-M., Decq. A., and Ball, S. 1994a. Genetic dissection of starch metabolism in the monocellular alga Chlamydomonas reinhardtii Determination of granule-bound and soluble starch synthases functions in amylopectin biosynthesis. J. Biol. Chem. 269, 25150-25157. 

Double mutants of the soluble starch synthases Starch synthases bound to the starch granule... 

A C. reinhardtii mutant lacking D-enzyme activity has been characterized and has been shown to have significantly lower levels of starch. Other enzymes involved in starch metabolism such as ADP-Glc PPase, granule-bound and soluble starch synthase, BE, phosphorylase, a-glucosidase, amylases, and debranching enzyme activities were not affected. The starch content in the mutant was about 6-13% of wild type and there was an excessive accumulation of maltooligosaccharides up to a polymer size of 16 glucose units. 

Edwards A., Marshall, J., Denyer, K., Sidebottom, C., Visser, R. G., Martin, C., and Smith, A. M. 1996. Evidence that a 77-kilodalton protein from the starch of pea embryos is an isoform of starch synthase that is both soluble and granule-bound. Plant Physiol. 112, 89-97. 

Denyer K, Hylton CM, Tenner CF, Smith AM. Identification of 37. multiple isoforms of soluble and granule-bound starch synthase... 

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