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Handbook of Size Exclusion Chromatography and Related ...

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Table 4 Key Enzymes in the Biosynthesis <strong>of</strong> Starch<br />

Enzyme Web-site !http://www.expasy.org/enzyme/<br />

ADP-Glc-pyrophsophorylase http://www.public.iastate.edu/ pkeeling/Enzpyro.htm<br />

EC 2.7.7.27 Glc-1-PO4adenylyltransferase<br />

http://www.expasy.org/cgi-bin/nicezyme.pl?2.4.1.27<br />

Granule bound starch synthase<br />

(GBSS)<br />

http://www.public.iastate.edu/ pkeeling/Enzgbss.htm<br />

EC 2.4.1.21 starch (bacterial<br />

glycogen) synth.<br />

http://www.expasy.org/cgi-bin/nicezyme.pl?2.4.1.21<br />

Starch synthase (SS) http://www.public.iastate.edu/ pkeeling/Enzss.htm<br />

EC 2.4.1.11 glycogen (starch)<br />

synthase<br />

http://www.expasy.org/cgi-bin/nicezyme.pl?2.4.1.11<br />

EC 2.4.1.21 starch (bacterial<br />

glycogen) synth.<br />

http://www.expasy.org/cgi-bin/nicezyme.pl?2.4.1.21<br />

Branching enzyme (BE) http://www.public.iastate.edu/ pkeeling/Enzbe.htm<br />

EC 2.4.1.18 (1!4)a<br />

glucan branching enzyme<br />

http://www.expasy.org/cgi-bin/nicezyme.pl?2.4.1.18<br />

EC 3.2.1.41 pullulanase http://www.expasy.org/cgi-bin/nicezyme.pl?3.2.1.41<br />

EC 3.2.1.68 isoamylase http://www.expasy.org/cgi-bin/nicezyme.pl?3.2.1.68<br />

Debranching enzyme http://www.public.iastate.edu/ pkeeling/Enzdebe.htm<br />

EC 3.2.1.41 pullulanase http://www.expasy.org/cgi-bin/nicezyme.pl?3.2.1.41<br />

EC 3.2.1.68 isoamylase http://www.expasy.org/cgi-bin/nicezyme.pl?3.2.1.68<br />

Disproportionating enzyme http://www.public.iastate.edu/<br />

Enzdispr.htm<br />

pkeeling/<br />

EC 2.4.1.25<br />

4-a-glucanotransferase<br />

http://www.expasy.org/cgi-bin/nicezyme.pl?2.4.1.25<br />

endosperm, potato tuber, <strong>and</strong> pea embryo to increase either the percentage <strong>of</strong><br />

nb-/lcb-glucan fraction (amylose) or <strong>of</strong> scb-glucans (amylopectin).<br />

No mutant has been found so far that lacks scb-glucans (amylopectin)<br />

completely; however, for several cases the ratio <strong>of</strong> lcb/scb-glucans could be<br />

significantly increased by breeding <strong>of</strong> hybrids such as amylomaize (17–19)<br />

or high amylose starch containing wrinkled pea varieties (20). Amylose-type<br />

nb/lcb-glucans are thus highly suspected to be some kind <strong>of</strong> remainders or<br />

byproducts <strong>of</strong> hydrolytic <strong>and</strong> transfer activities during starch biosynthesis.<br />

Awide variety <strong>of</strong> mutants are, however, known that contain minor or<br />

negligible amounts <strong>of</strong> nb-glucans (21–26). The responsible maize waxy mutant<br />

was found decades ago <strong>and</strong> was optimized by breeding over anumber <strong>of</strong> years to<br />

achievestarcheswithhighyields<strong>of</strong>scb-glucans.Availablewaxymutantsinclude:<br />

maize, wheat (27), barley (28), rice (29) (monocots), pea (30), <strong>and</strong> amaranth (31)<br />

(dicots).<br />

© 2004 by Marcel Dekker, Inc.

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