The phosphorylation site in double helical amylopectin as investigated by a combined approach using chemical synthesis, crystallography and molecular modeling

FEBS Letters

Engelsen, Søren Balling²  Madsen, Anders Østergaard³  Blennow, Andreas¹  Møller, Birger Lindberg¹  Motawia, Mohammed Saddik¹  Larsen, Sine³ 

[1] Plant Biochemistry Laboratory, Center for Molecular Plant Physiology (PlaCe), Department of Plant Biology, The Royal Veterinary and Agricultural University, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Denmark;Food Technology, Department of Dairy and Food Science, The Royal Veterinary and Agricultural University, Rolighedsvej 30, DK-1958 Frederiksberg C, Denmark;Centre for Crystallographic Studies, Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark

关键词: Glucose;    Amylopectin;    Phosphate;    Double helix;    Structure;   

DOI  :  10.1016/S0014-5793(03)00311-9

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The only known in planta substitution of starch is phosphorylation. Whereas the function of starch phosphorylation is poorly understood, phosphorylated starch possesses improved functionality in vitro. Molecular models of native crystalline starch are currently being developed and the starch phosphorylating enzyme has recently been discovered. Accordingly, it is desirable to obtain a more exact description of the molecular structures of phosphorylated starch. We have determined the crystal structure of methyl α-D-glucopyranoside 6-O-phosphate as its potassium salt which is thought to be the starch phosphate counterion in vivo. From this structure and previously known glucophosphate structures we describe the possible 6-O-phosphate geometries and through modeling extrapolate the results to the double helical structure of the crystalline part of amylopectin. The geometries of the existing crystal structures of 6-O-phosphate groups were found to belong to two main adiabatic valleys. One of these conformations could be fitted into the double helical amylopectin part without perturbing the double helical amylopectin structure and without creating steric problems for the hexagonal chain–chain packing.

【 授权许可】

Unknown