Källman, Anna
- Department of Molecular Sciences, Swedish University of Agricultural Sciences
Abstract
Molecular structures of starches from dull1 maize mutants deficient in starch synthase Ill (SSIII) with a common genetic background (W64A) were characterized and compared with the wild type. Amylose content with altered structure was higher in the nonwaxy mutants (25.4-30.2%) compared to the wild type maize (21.5%) as revealed by gel permeation chromatography. Superlong chains of the amylopectin component were found in all nonwaxy samples. Unit chain length distribution of amylopectins and their phi,beta-limit dextrins (reflecting amylopectin internal structure) from dull1 mutants were also characterized by anion-exchange chromatography after debranching. Deficiency of SSIII led to an increased amount of short chains (DP <= 36 in amylopectin), whereas the content of long chains decreased from 8.4% to between 3.1 and 3.7% in both amylopectin and phi,beta-limit dextrins. Moreover, both the external and internal chain lengths decreased, suggesting a difference in their cluster structures. Whereas the molar ratio of A:B-chains was similar in all samples (1.1-1.2), some ratios of chain categories were affected by the absence of SSIII, notably the ratio of "fingerprint" A-chains to "clustered" A-chains. This study highlighted the relationship between SSIII and the internal molecular structure of maize starch.
Keywords
dull1 maize mutant; starch synthase III; starch structure; internal structure
Published in
Journal of Agricultural and Food Chemistry
2013, volume: 61, number: 41, pages: 9899-9907
Publisher: AMER CHEMICAL SOC
SLU Authors
UKÄ Subject classification
Agricultural Science
Publication identifier
- DOI: https://doi.org/10.1021/jf402090f
Permanent link to this page (URI)
https://res.slu.se/id/publ/54915