110
was in disagreement with the “theory of physical solution,” i.e., a physical solution
occurred when iodine dissolved in the helices as in hydrocarbons (Kainuma 1984).
At that time, the young student also studied the formation of cycloamylosescyclodextrins with the expectation that they would shed some light on the molecular
structure of amylose. Indeed, for him, the degradation of starch to a mixture of
cyclic and acyclic dextrins (Fig. 2.7) by the action of Bacillus macerans was an
interesting reaction in the elaboration of a possible interpretation of the amylose
conformation. This was a first step closer to cycloamyloses-cyclodextrins. Later,
Professor Szejtli clearly demonstrated that the formation of cyclodextrins, catalyzed
by cyclodextrin-glycosyl-transferase enzyme, delivered further proof for the helical
structure of amylose (Szejtli 1971, 1991c).
At the end of the 1960s, Szejtli investigated the hydrolysis of starch (Holló and
Szejtli 1959a, b), retrogradation of amylose (Holló et al. 1959a, b, c), and mechanism of the gelatinization of potato starch by measuring the amount of the adsorption of iodine and the polarographic maxima suppression power and by the
measurement of the light permeability of the suspension (Holló et al. 1962, 1964;
Szejtli 1963).
The results showed that the hydrolysis reaction was the resultant of two simultaneously occurring processes, the splitting of the terminal and of nonterminal bonds.
The velocity of retrogradation decreased with increasing temperature and potato
amylose containing one to two ramifications per molecule aged less rapidly than
wheat amylose containing no ramification. The mechanism consisted of three
stages: (1) the randomly linked helices were stretched by an intake of energy; (2)
after losing their hydrate water hulls, the chains arranged themselves one after the
other; and (3) a crystalline structure was formed due to the formation of hydrogen
bonds between the hydroxyls of amylose.
At the Technical University of Trondheim, Dr. Szejtli pursued his studies on the
characterization of structure and hydrolysis of starch (Szejtli 1965a). He also studied the hydrolysis of other polysaccharides such as dextran (Szejtli 1965b) and
alginic acid (Szejtli 1965c). He highlighted a relation between the composition and
the IR spectra of polysaccharides of different origins (Szejtli 1966).
During his postdoctoral stay at Potsdam, Dr. Szejtli continued to study the
molecular configuration of amylose and its complexes in aqueous solutions (Richter
and Szejtli 1966; Szejtli and Augustat 1966; Szejtli et al. 1967a, b, 1968). Studying
the amylose-iodine complex at low pH (Fig. 2.8), Dr. Szejtli demonstrated that helices existed in segments and pointed out the fact that the stability of the complexes
was dependent on the length of the polyiodide chains, and this length is dependent
on the degree of polymerization of amylose (Szejtli et al. 1967a). A value of 100–200
for the chain length was the limit where the rigid linear helix was replaced by a flexible segmented coil form (Szejtli and Augustat 1966; Szejtli et al. 1967a). Other
factors, such as temperature, pH, and concentration of iodide and starch, were also
important (Szejtli et al. 1967b). For the first time, Dr. Szejtli suggested the hostguest complexes with amylose helix: this was another step closer to
cycloamyloses-cyclodextrins.
G. Crini et al.
was in disagreement with the “theory of physical solution,” i.e., a physical solution
occurred when iodine dissolved in the helices as in hydrocarbons (Kainuma 1984).
At that time, the young student also studied the formation of cycloamylosescyclodextrins with the expectation that they would shed some light on the molecular
structure of amylose. Indeed, for him, the degradation of starch to a mixture of
cyclic and acyclic dextrins (Fig. 2.7) by the action of Bacillus macerans was an
interesting reaction in the elaboration of a possible interpretation of the amylose
conformation. This was a first step closer to cycloamyloses-cyclodextrins. Later,
Professor Szejtli clearly demonstrated that the formation of cyclodextrins, catalyzed
by cyclodextrin-glycosyl-transferase enzyme, delivered further proof for the helical
structure of amylose (Szejtli 1971, 1991c).
At the end of the 1960s, Szejtli investigated the hydrolysis of starch (Holló and
Szejtli 1959a, b), retrogradation of amylose (Holló et al. 1959a, b, c), and mechanism of the gelatinization of potato starch by measuring the amount of the adsorption of iodine and the polarographic maxima suppression power and by the
measurement of the light permeability of the suspension (Holló et al. 1962, 1964;
Szejtli 1963).
The results showed that the hydrolysis reaction was the resultant of two simultaneously occurring processes, the splitting of the terminal and of nonterminal bonds.
The velocity of retrogradation decreased with increasing temperature and potato
amylose containing one to two ramifications per molecule aged less rapidly than
wheat amylose containing no ramification. The mechanism consisted of three
stages: (1) the randomly linked helices were stretched by an intake of energy; (2)
after losing their hydrate water hulls, the chains arranged themselves one after the
other; and (3) a crystalline structure was formed due to the formation of hydrogen
bonds between the hydroxyls of amylose.
At the Technical University of Trondheim, Dr. Szejtli pursued his studies on the
characterization of structure and hydrolysis of starch (Szejtli 1965a). He also studied the hydrolysis of other polysaccharides such as dextran (Szejtli 1965b) and
alginic acid (Szejtli 1965c). He highlighted a relation between the composition and
the IR spectra of polysaccharides of different origins (Szejtli 1966).
During his postdoctoral stay at Potsdam, Dr. Szejtli continued to study the
molecular configuration of amylose and its complexes in aqueous solutions (Richter
and Szejtli 1966; Szejtli and Augustat 1966; Szejtli et al. 1967a, b, 1968). Studying
the amylose-iodine complex at low pH (Fig. 2.8), Dr. Szejtli demonstrated that helices existed in segments and pointed out the fact that the stability of the complexes
was dependent on the length of the polyiodide chains, and this length is dependent
on the degree of polymerization of amylose (Szejtli et al. 1967a). A value of 100–200
for the chain length was the limit where the rigid linear helix was replaced by a flexible segmented coil form (Szejtli and Augustat 1966; Szejtli et al. 1967a). Other
factors, such as temperature, pH, and concentration of iodide and starch, were also
important (Szejtli et al. 1967b). For the first time, Dr. Szejtli suggested the hostguest complexes with amylose helix: this was another step closer to
cycloamyloses-cyclodextrins.
G. Crini et al.