Potato D-enzyme catalyses an intramolecular transglycosylation reaction on amylose to produce cycloamylose, a novel cyclic α-1,4 glucan. To determine if a similar activity could be observed with a high molecular weight branched substrate, recombinant potato D-enzyme was incubated with amylopectin. The substrate was converted into two fractions of lower molecular mass. Fraction I comprised 15% cyclic molecules of which the majority contained both α-1,4 and α-1,6 links. These were shown to be branched molecules with branches shorter than those in amylopectin. Fraction II comprised 80% cyclic molecules of which the majority contained only α-1,4 links (cycloamylose). Since fraction II appeared before fraction I, we propose that D-enzyme first catalysed the cyclisation of the outer side chains of amylopectin and then the cyclisation of inner chains to produce branched clusters. These results demonstrate that D-enzyme can catalyse the transfer of branched glucans, and suggest novel ways in which it may participate in starch metabolism in plants.

Item Type:	Refereed Article
Keywords:	cyclic glucans, intramolecular transglycosylation, potato d-enzyme, amylopectin, 4-a-glucanotransferase
Research Division:	Biological Sciences
Research Group:	Plant Biology
Research Field:	Plant Physiology
Objective Division:	Expanding Knowledge
Objective Group:	Expanding Knowledge
Objective Field:	Expanding Knowledge in the Biological Sciences
UTAS Author:	Smith, SM (Professor Steven Smith)
ID Code:	101570
Year Published:	1998
Web of Science® Times Cited:	37
Deposited By:	Plant Science
Deposited On:	2015-06-26
Last Modified:	2015-09-21
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