Starch Biosynthesis. I. The Size Distributions of Amylose and Amylopectin and Their Relationships to the Biosynthesis of Starch

Starch Biosynthesis. II. The Statistical Model for Amylopectin and Its Precursor Plant Glycogen

“…As seen in Fig. 2 the dip in the curve for the model corresponds to the dip in the curves observed before [11] for various amylopectins and thus illustrates again that the dip is due to a missing short chain polymer.…”

“…Hence, better agreement was obtained with experimental results when the size distribution of the linear chains of amylopectin were restricted by assuming rods of ten or so glucose units in length to represent the chains between branch points. This much narrower size distribution was supported in the previous paper [11] by the examination of the polymodal be-havior of debranched amylopectin chains, where it was shown that these linear chains can be correlated with several distinct polymers, each of which correlates with the very narrow Poisson size distribution. Thus the previously used [9,10] rod structures were actually a rough representation of the very narrow Poisson size distribution for a statistically branched polymer.…”

“…Ideally, the amylopectin should not have in its structure any chains which have approximately x n = 10 since the debranching mechanism in its conversion of glycogen to amylopectin should be able to remove these chains. However, previous results [11] indicate that there may be two or even three polymers which have degrees of polymerization which are much less than about _ x n = 20. In order to explain this observation, it can be concluded that there exist in the precursor glycogen and in its amylopectin, interior chains which have been blocked from growing because of steric hindrance and which also were not removed in the partial debranching of the precursor glycogen, again because of steric hindrance to the debranching enzyme.…”

“…It it is assumed that each polymer described above has a Poisson size distribution, then the weight fraction of a particular chain X units long for a specific polymer can be calculated from the equation given for the Poisson size distribution as shown previously [11]. In a mixture of many polymers, this particular chain length could come from more than one polymer, such as a chain of X = 15 glucose units would exist in the A-1 and A-2 polymer and possibly in the B-3 polymer.…”

Changes of Thermodynamic and Structural Properties of Potato Starches (Udacha andAcrosil Varieties) during Biosynthesis

“…According to [4], an increase in amylose content in potato starches leads to an increase in granular sizes and molecular weights of amylose and amylopectin. Recently, some concepts concerning mechanisms of amylose and amylopectin biosynthesis were considered by Erlander [7,8] and Ball et al [9]. However, formation processes of different supramolecular polymorphous structures in starch granules remain incompletely understood.…”