Amylopectin Chain Length Distribution Research Articles

Quantitative analysis of amylopectin unit chains by means of high-performance anion-exchange chromatography with pulsed amperometric detection

High-performance anion-exchange chromatography with pulsed amperometric detection (HPAEC–PAD) is a widely used technique to study the chain length distribution of amylopectin. The chromatograms, however, do not directly reflect this distribution, since the PAD response changes with the degree of polymerization. In this study, waxy maize starch was debranched and fractionated on a Bio-Gel P-6 column and the response factors for maltosaccharides with DP 3–65 were determined. The detector response per μg glucan chains was shown to decrease considerably for DP 3–7 while the curve leveled out for DP larger than 15.

Difference of Side Chain Length Distribution of Amylopectin in White Belly, White Core and Perfect Rice Grains

Difference of Side Chain Length Distribution of Amylopectin in White Belly, White Core and Perfect Rice Grains

Combined effects of planting and harvesting dates on starch properties of sweet potato roots

Starch was extracted from sweet potato roots differing in planting and harvesting dates. The physicochemical properties of the isolated starches were analyzed. Amylose content was found to be almost independent of both planting and harvesting dates. The proportions of the short chains of amylopectin were lower at the earliest harvesting, while the planting date had little influence on the chain length distribution of amylopectin. Not only the harvesting date but also the planting date were confirmed to have a profound effect on pasting and gelatinization properties determined by rapid viscoanalyzer (RVA) and differential scanning calorimetry (DSC), respectively. Earlier planting and harvesting apparently enhanced the onset and peak temperatures for gelatinization determined by DSC and the pasting temperature determined by RVA. Furthermore, earlier planting and harvesting dates were generally associated with lower peak viscosity determined by RVA. The effect of planting and harvesting dates on the mean size of starch granules, starch granule digestibility by glucoamylases and X-ray diffractograms of starch was also investigated.

A periodic distribution of the chain length of amylopectin as revealed by high-performance anion-exchange chromatography

The chains of amylopectin over dp 80 were separated on baseline resolution by high-performance anion-exchange chromatography with pulsed amperometric detection under improved conditions, and the chain-length (cl) distributions of amylopectins from eleven plant sources were analyzed. The differences in amount of each chain between arrowhead ( Sagittaria trifolia L. var. sinensis Makino) and other kinds of amylopectins exhibited periodic waves which divided the abscissa at intervals of dp 12, except those of edible canna and yam amylopectins, where the interval was of the order of dp 15. Accordingly, chain-length distributions were fractionated into fa, dp 6–12; fb 1, dp 13–24; fb 2, dp 25–36, and fb 3, dp >37. Amylopectin with short and long cl n had large and small amounts of the fa fraction, respectively, and showed A and B type X-ray diffractions of starch granules. The amount of the fa fraction was suggested to play an important role in the determination of starch crystalline polymorphs.

Influence of Side Chain Length Distribution of Amylopectin on the Fine Structure and Taste of Cooked Rice

Influence of Side Chain Length Distribution of Amylopectin on the Fine Structure and Taste of Cooked Rice

Distributions of the Amylopectin Chain Length of Sweet Potatoes Differing in Stages of Development, Tissue Zone and Variety.

Starches were extracted from sweet potatoes differing in stages of development, tissue zone and variety. A series of maltosaccharides produced after debranching each starch with isoamylase were analyzed using high performance anion exchange chromatography equipped with a pulsed amperometric detector. Using this method, the chain length [degree of polymerization (DP), 6-17] distributions of amylopectin molecules were characterized to evaluate the influence of genetic and physiological factors on the properties of sweet potato amylopection. No significant changes were observed in the chain length distributions of amylopectins at various stage of development. In addition, no significant differences were observed in the chain length distributions of amylopectins from different tissue zones. Therefore, it was suggested that physiological conditions have very little effect on the molecular structure of sweet potato amylopectin. Only small variations in the chain length distributions of amylopectins were observed within 31 varieties of sweet potato. The proportion of short chains in the range of DP of 6-10 ranged from 28.7% (Tokai 5) to 37.6% (Kyushu 91) within these varieties.

Simultaneous determinations of the molecular weight distributions of amyloses and the fine structures of amylopectins of native starches

Native A (wheat and waxy rice), B (potato), and C (cassava and sweet potato) types of starches were each debranched with isoamylase, and separated into amylose and amylopectin fractions by HPLC on size exclusion columns coupled on-line to multi-angle-laser-light-scattering and differential refractometer detectors. The absolute molecular weights of amyloses and chain length distributions of amylopectins were determined simultaneously, and pre-isolation of the amylopectin was not necessary. The molecular weights of debranched amylose from starches that have not been fractionated to separate amylose and amylopectin are significantly higher than published values for the undebranched fractionated amylose. The polymodal profiles of the refractive index chromatograms showed the complexity of the amylopectin structure of starches. The chain length distribution of amylopectin depends critically on the method for analysing the broad chromatogram when determined by either noting the minima/inflections or deconvoluting the overlapping amylopectin fraction into numerous normal/Gaussian distributions. Although the results from the former (conventional) method of analysis were comparable with the literature values, they did not appear to be as sensitive a technique for detecting differences as the multiple Gaussian approach. Overall, the study suggested that the amylopectin chain units might be more complex than originally envisaged and that different degrees of chain packing for the molecules can be inferred from this multiple component analysis.

Estimation of the distributions of chain length of amylopectins by high-performance liquid chromatography with pulsed amperometric detection

High-performance anion-exchange chromatography for a detailed estimation of the distribution of chain length of amylopectins was developed using a pulsed amperometric detector under alkaline conditions. As maltosaccharides having different degrees of polymerization, which were produced by debranching of amylopectin with isoamylase, exhibit different pulsed amperometric detector responses, the individual maltosaccharides (degree of polymerization 6–17) were isolated by high-performance liquid chromatography on an amino column and an octadecylsilane column to use as quantification standards. By the use of this high-performance anion-exchange chromatography the chain length distributions of some typical amylopectins were characterized in detail.

Chain Length Distribution of Amylopectins of Several Single Mutants and the Normal Counterpart, and Sugary‐1 Phytoglycogen in Maize (Zea mays L.)

Abstractβ‐Limit dextrins of starches of normal (nonmutant), amylose‐extender (ae), dull (du), sugary‐2 (su2) and waxy (wx) maize, and phytoglycogen of sugar‐1 (su1) maize were prepared. The β‐limit dextrins were successively debranched by isoamylase and pullulanase, and followed by quantitative gel‐filtration.The ratio of A to B chains for the ae starch appeared to be high and that for su1 phytoglycogen was low. The ratio of short B to long B chains for the du starch was high and that for the ae starch appeared to be low. The phytoglycogen did not contain long B chains. The unit chain‐length distribution of amylopectins of the normal, wx, and su2 starches were similar. Fine structures of maize amylopectins and su1 phytoglycogen were modeled and described.

Chain Length Distribution of Amylopectins of Double- and Triple-Mutants Containing the Waxy Gene in the Inbred Oh43 Maize Background

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