Campus Units
Biochemistry, Biophysics and Molecular Biology, Roy J. Carver Department of
Document Type
Article
Publication Version
Published Version
Publication Date
11-25-2016
Journal or Book Title
Journal of Biological Chemistry
Volume
291
Issue
48
First Page
24951
Last Page
24960
DOI
10.1074/jbc.M116.754705
Abstract
A comprehensive description of starch biosynthesis and granule assembly remains undefined despite the central nature of starch as an energy storage molecule in plants and as a fundamental calorie source for many animals. Multiple theories regarding the starch synthase (SS)-catalyzed assembly of (α1–4)-linked D-glucose molecules into maltodextrins generally agree that elongation occurs at the non-reducing terminus based on the degradation of radiolabeled maltodextrins, although recent reports challenge this hypothesis. Surprisingly, a direct analysis of the SS catalytic product has not been reported, to our knowledge. We expressed and characterized recombinant Zea mays SSIIa and prepared pure ADP-[13CU]glucose in a one-pot enzymatic synthesis to address the polarity of maltodextrin chain elongation. We synthesized maltoheptaose (degree of polymerization 7) using ADP-[13CU]glucose, maltohexaose (degree of polymerization 6), and SSIIa. Product analysis by ESI-MS revealed that the [13CU]glucose unit was added to the non-reducing end of the growing chain, and SSIIa demonstrated a >7,850-fold preference for addition to the non-reducing end versus the reducing end. Independent analysis of [13CU]glucose added to maltohexaose by SSIIa using solution NMR spectroscopy confirmed the polarity of maltodextrin chain elongation.
Copyright Owner
The American Society for Biochemistry and Molecular Biology, Inc.
Copyright Date
2016
Language
en
File Format
application/pdf
Recommended Citation
Larson, Mark E.; Falconer, Daniel J.; Myers, Alan M.; and Barb, Adam W., "Direct Characterization of the Maize Starch Synthase IIa Product Shows Maltodextrin Elongation Occurs at the Non-reducing End" (2016). Biochemistry, Biophysics and Molecular Biology Publications. 204.
https://lib.dr.iastate.edu/bbmb_ag_pubs/204
Included in
Biochemistry Commons, Biophysics Commons, Molecular Biology Commons, Structural Biology Commons
Comments
This research was originally published in the Journal of Biological Chemistry. Larson, Mark E., Daniel J. Falconer, Alan M. Myers, and Adam W. Barb. "Direct characterization of the maize starch synthase IIa product shows maltodextrin elongation occurs at the non-reducing end." Journal of Biological Chemistry 291, no. 48 (2016): 24951-24960. © the American Society for Biochemistry and Molecular Biology. doi: 10.1074/jbc.M116.754705.