The Mechanism for the Synthesis of Starch and Its Relationship to Flagellin and to the Newly Proposed Structural Model for DNA. Part II.

All of the components and enzymes required for the synthesis of starch by the glycogen precursor method have now been shown to exist. In this mechanism, the genetic inducer sucrose stimulates the production of phosphorylase and the Q-enzyme. These and other enzymes in turn convert sucrose to glycogen. The external branches of the glycogen are then removed by the debranching enzyme isoamylase. The removed branches act as substrates, necessary co-enzymes, suppliers of adenosine diphosphate glucose (ADPG), and possibly genetic inducers for the production and enzymatic activity of glucosyltransferase. They are converted into ADPG by the D-enzyme plus other enzymes and then into amylose. Consequently, the percentage of amylose is directly proportional to the degree of debranching of amylopectin, which in turn is determined by how long amylopectin can be retained in the plastid solution before precipitating with isoamylase or other enzymes to form starch. The ability of the above specialized mechanisms to occur in the same solution is thus a result of selective complexing of enzymes to different polysaccharides and the production of different genetic inducers. Thus the interaction of different inducers with DNA repressors determines the time-sequence for the production of specific enzymes. The thermal stability of thermophile flagellins and the inability of 6 M guanidinium chloride (GCl) to dissociate mesophile flagellin dimers (M_w = 40,000) or thermophile flagellin trimers (M_w 54,000) supports the conclusion that protein-amylopectin complexes exist and cannot be readily dissociated. Because hydroxyls are involved in these flagellin aggregates, then the hydroxyls of much larger amylopectin molecules should also be able to form similar stable bonds with proteins. It is proposed that mutations can be caused by either elimination of active genes by feed-back mechanisms (permanent repressors) or by chemicals and radiation. New genetic strains of grains produced by radiation for resistance to pests can thus only lead to disaster. Improvement of the soil is the only means for the production of lasting resistant strains.