Relationship between the nanometer-scale structures of amylopectin molecules and temperature dependence of internal structures of starch granules in endosperm of starch branching enzyme 2b (be2b) allelic mutant lines from japonica rice

• Published in: Results in Chemistry Vol. 9; p. 101660
• Main Authors: Yashiro, Kazuki, Sato, Shiho, Kondo, Yuta, Nakamura, Yasunori, Yano, Hiroko, Koda, Tomonori, Nishioka, Akihiro, Takashima, Yoshinori, Matsuba, Go
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.07.2024; Elsevier
• Subjects: Branching enzyme mutation; Japonica rice starch; Nanometer-scale structure; Branching enzyme mutation; Nanometer-scale structure; Japonica rice starch
• ISSN: 2211-7156; 2211-7156
• DOI: 10.1016/j.rechem.2024.101660

[Display omitted] •The crystal, and nanoscale cluster of the starch granules varied among mutant lines.•The surface of the starch granules depends on crystal structure.•The gelatinization temperature depends on branch length and density.•The nano-meter scaled structural change was observed with in-situ experiments. We analyzed the relationship between the nanometer-scale structure of amylopectin and physicochemical properties such as thermal properties of starch granules and higher-order internal structure of starch granules evaluated by using synchrotron radiation X-ray scattering and scanning electron microscopy. In this study, a line of allelic mutants of rice lacking in starch branching enzyme IIb (BEIIb) activity in their endosperm were used as starch sources. The crystal lattice changed from A-type to C- and B-type. The nanoscale cluster size, and higher-order structures of the starch granules varied among mutant lines. The thermal gelatinization properties of the rice-derived starch samples, as well as the dependence of this process on their crystal structure, were evaluated using differential scanning calorimetry and synchrotron X-ray scattering. After gelatinization, several nm-scaled density fluctuations owing to the formation of gel balls were observed. These fluctuations of all starch samples correlated with the cluster size decreased with the temperature.