The interaction of linear, amylose oligomers with iodine

Banks, W.; Greenwood, C. T.; Khan, Khalid M.

doi:10.1016/s0008-6215(00)81539-6

Cited by 167 publications

(91 citation statements)

References 17 publications

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“…The same results were obtained with Atisa2-1. This result could partly explain the increase in l max of the residual amylopectin observed in both lines since glucans shorter than 12 Glc residues in length are unable to interact with iodine (Banks et al, 1971). …”

Section: Structural Analysis Of Mutant Amylopectin and Wspmentioning

confidence: 94%

Mutants of Arabidopsis Lacking a Chloroplastic Isoamylase Accumulate Phytoglycogen and an Abnormal Form of Amylopectin

et al. 2005

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Mutant lines defective for each of the four starch debranching enzyme (DBE) genes (AtISA1, AtISA2, AtISA3, and AtPU1) detected in the nuclear genome of Arabidopsis (Arabidopsis thaliana) were produced and analyzed. Our results indicate that both AtISA1 and AtISA2 are required for the production of a functional isoamylase-type of DBE named Iso1, the major isoamylase activity found in leaves. The absence of Iso1 leads to an 80% decrease in the starch content in both lines and to the accumulation of water-soluble polysaccharides whose structure is similar to glycogen. In addition, the residual amylopectin structure in the corresponding mutant lines displays a strong modification when compared to the wild type, suggesting a direct, rather than an indirect, function of Iso1 during the synthesis of amylopectin. Mutant lines carrying a defect in AtISA3 display a strong starch-excess phenotype at the end of both the light and the dark phases accompanied by a small modification of the amylopectin structure. This result suggests that this isoamylase-type of DBE plays a major role during starch mobilization. The analysis of the Atpu1 single-mutant lines did not lead to a distinctive phenotype. However, Atisa2/Atpu1 double-mutant lines display a 92% decrease in starch content. This suggests that the function of pullulanase partly overlaps that of Iso1, although its implication remains negligible when Iso1 is present within the cell.

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Section: Structural Analysis Of Mutant Amylopectin and Wspmentioning

confidence: 94%

Mutants of Arabidopsis Lacking a Chloroplastic Isoamylase Accumulate Phytoglycogen and an Abnormal Form of Amylopectin

et al. 2005

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“…lipids, alcohols and iodine (Zobel 1988). With iodine, a coloured complex is formed, with colour intensity and wavelength for maximal extinction (λ max ) depending on the concentration and average chain length of amylose (Bailey & Whelan 1961;Banks et al 1971). The minimum chain length necessary for iodine colour formation is 18 glucose units (Bailey & Whelan 1961).…”

Section: The Substrate: Amylose and Amylopectinmentioning

confidence: 99%

Amylase action pattern on starch polymers

2008

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Several decades ago, the first reports on differences in action pattern between amylases from different sources indicated that the starch polymers are not degraded in a completely random manner. We here give an overview of different action patterns of amylases on amylose and amylopectin, focusing on the so-called multiple attack action of the enzymes. Nowadays, the multiple attack action is generally an accepted concept to explain the differences in amylase action pattern. However, the pancreatic α-amylase remains one of the few enzymes known with a considerable level of multiple attack action. Despite some recent studies, the molecular mechanism of the multiple attack action is still largely unclear. Probably, the degree to which the active site architecture and binding properties allow both the reorganization (sliding) of the substrate in the active site and the stabilisation of the productive enzyme/substrate complex mainly determine the multiple attack action of amylases.

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“…The optical density of the iodine polysaccharide complex was monitored for each 2-mL fraction at l max . The (average) DP scale was generated by using the l max values of the debranched glucans as internal standards (Banks et al, 1971). The values listed in the table are Glc weight percentages estimated by the amyloglucosidase assay by summing Glc amounts corresponding to those fractions corresponding to the average DP scale.…”

Section: Gbssi Is a Major Enzyme Of Amylopectin Synthesis In Oscillatmentioning

confidence: 99%

Circadian Clock Regulation of Starch Metabolism Establishes GBSSI as a Major Contributor to Amylopectin Synthesis in Chlamydomonas reinhardtii

et al. 2006

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Chlamydomonas reinhardtii displays a diurnal rhythm of starch content that peaks in the middle of the night phase if the algae are provided with acetate and CO 2 as a carbon source. We show that this rhythm is controlled by the circadian clock and is tightly correlated to ADP-glucose pyrophosphorylase activity. Persistence of this rhythm depends on the presence of either soluble starch synthase III or granule-bound starch synthase I (GBSSI). We show that both enzymes play a similar function in synthesizing the long glucan fraction that interconnects the amylopectin clusters. We demonstrate that in log phase-oscillating cultures, GBSSI is required to obtain maximal polysaccharide content and fully compensates for the loss of soluble starch synthase III. A point mutation in the GBSSI gene that prevents extension of amylopectin chains, but retains the enzyme's normal ability to extend maltooligosaccharides, abolishes the function of GBSSI both in amylopectin and amylose synthesis and leads to a decrease in starch content in oscillating cultures. We propose that GBSSI has evolved as a major enzyme of amylopectin synthesis and that amylose synthesis comes as a secondary consequence of prolonged synthesis by GBSSI in arrhythmic systems. Maintenance in higher plant leaves of circadian clock control of GBSSI transcription is discussed.

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The interaction of linear, amylose oligomers with iodine

Cited by 167 publications

References 17 publications

Mutants of Arabidopsis Lacking a Chloroplastic Isoamylase Accumulate Phytoglycogen and an Abnormal Form of Amylopectin

Mutants of Arabidopsis Lacking a Chloroplastic Isoamylase Accumulate Phytoglycogen and an Abnormal Form of Amylopectin

Amylase action pattern on starch polymers

Circadian Clock Regulation of Starch Metabolism Establishes GBSSI as a Major Contributor to Amylopectin Synthesis in Chlamydomonas reinhardtii

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