Starch Phosphorylation

Starch is by far the most important molecular principle for providing energy storage for plants and in turn for human and animal energy intake. The impact of starch stems from its hyper-efficient deposition of glucose in semicrystalline granules combined with its high ability to be made bioavailable in the plant despite the high density and crystallinity that normally prevents hydrolytic enzymes to efficiently attack the granule. A new carbohydrate model can now explain the structural basis for how rare phosphate esters present in starch granules can stimulate its degradation in the cell. Glucan water dikinases track and tag crystalline sites and then execute 3-phosphorylation of few glucose residues generating kinks in the regular helical glucosidic bond structure creating local disorder. This finding adds new perspective on how organisms increase bioavailability of a carbohydrate matrix by inducing amorphisation by a phosphate-induced tracker – executor mechanism.

 

 

Selected publications

Blennow, A. and Engelsen, S.B. (2010) Helix-breaking news: fighting crystalline starch energy deposits in the cell. Trends Plant Sci. 15(4):236-240

doi:10.1016/j.tplants.2010.01.009 |

 

Hansen, P.I., Spraul, M., Dvortsak, P., Larsen, F.H., Blennow, A., Motawia, S.M.  and Engelsen, S.B. (2009) Starch phosphorylation – maltosidic restrains upon 3’- and 6’- phosphorylation investigated by chemical synthesis, molecular dynamics modeling and NMR spectroscopy. Biopolymers 91/3: 179-193. DOI: 10.1002/bip.21111

 

Wikman, J., Larsen, F.H., Motawia, M.S., Blennow, A. and Bertoft, E. (2011) Phosphate esters in amylopectin clusters of potato tuber starch. International Journal of Biological Macromolecules, 48, 639-649.