Studies on the Fine Structure of Starch Molecules and Novel Starch Related Enzymes

Abstract

Researches on structural analysis, physical properties of starch and discoveries of novel starch related enzymes are summarized in this paper as an award address. 1) Physical properties and utilization of various starches Starch phosphate derivatives obtained by chemical synthesis or simple cation substitution of naturally existing phosphate of potato starch are discussed in terms of physical properties and possible utilization. Sago starch as a. neglected starch resource in tropical area and newly developed methodology during the study such as photopastegraphy, Q-amylase/pullulanase method (BAP method) are also described. 2) Fine structure of amylopectin: Fine structures of waxy maize starch were analyzed by structure of a-limit dextrin, X-ray diffraction and enzymic structural analysis of Naegeli amylodextrin, transmission electron microscopy and computer modeling. From the results of these studies, French proposed?gcluster model?hfor amylopectin molecules and Kainuma and French proposed?gdouble helix?hconformation for crystalline part of amylopectin. In 1980, Kainuma represented schematic arrangement of amylopectin molecules within a growth ring. 3) Novel starch related enzymes and oligosaccharides: During structural analysis, exo-maltohexaohydrolase (E. C. 3.2.1.98) was unexpectedly discovered as a contaminant of A. aero genes pullulanase. Since this discovery, our research efforts were concentrated to screen new starch related enzymes and enzymatic preparation of oligosaccharides. As the results, cyclodextrins and branched cyclodextrins, isomaltose, maltohexaose, erythritol -a noncaloric sweetener-were already commercially manufactured. Raw starch hydrolyzing glucoamylase of Chalara paradoxa isolated from sago palm tree in Papua New Guinea is expected for energy-saving saccharification of starch.