Branched glucans, synthesis

Synthesis of the 1,6-a-D-glucose bonds in amylopectin is catalyzed by a branching enzyme [E.C. 2.4.1.18 1,4-a-D-glucan 6-a-(l,4-a-glucano)-transferase reaction 3]. Amylopectin contains longer chains (about 20-24 glucosyl units) and has less... 

A mutant of starch synthase II has also been isolated in C. reinhardtiL This mutant, st-3, accumulated only 20-40% of amount of starch present in wild type. The enzyme lacking in the mutant was SSII, one of the two starch synthase isoforms present in C. reinhardtii There was also an apparent increase in the amyiose content as well as a modified form of amylopectin. The changes noted in the mutant amylopectin were, a decrease in the number of intermediate glucose branch chains of 8-50 glucose units and an increase in short-chain glucans (2—7 glucose units). The conclusion made was that this SSII was responsible for synthesis of intermediate size branch chains, a similar conclusion reached as indicated above with the function of SSII and SSIIa in higher plants. The SSII of Chlamydomonas is now referred to as SSIII. ... 

Satoh, T., et al., Synthesis, branched structure, and solution property of hyperbranched D-glucan and D-galactan. Macromolecules 38(10) 4202-4210, 2005. 

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