Formation of Superstructural Bilayers and Enzyme Model Reaction by Telomer-type Surfactants.

点击翻译按钮获取中文摘要

1. Double-chain alkyl derivatives with poly(L-glutamic acid)- and poly(L-aspartic acid)-head groups were synthesized and their aggregate morphologies in dilute aqueous solutions were investigated. These polyamino acid derivatives were dispersed in water at above pH 4 to form a variety of helical superstructures composed of single-walled bilayer membranes, whose morphologies were closely related to the chemical structures of hydrophilic head groups. The helical structures were not observed in the corresponding ammonium amphiphiles without polyamino acid-head groups and the amphiphile with low-molecular head groups or with poly(DL-amino acid) head groups. The developmental mechanism to helical superstructures was concluded by following the metamorphosis of bilay reaggregates from poly(L-aspartic acid) derivatives in aqueous solutions:the helical forms are induced via the formation of double or multiple helix among the untwisted filaments produced by incubating.2. Chiral ester cleavage by … More achiral hydroxamic acids was investigated in the presence of chiral matrix micelles formed from amphiphiles with poly-L-lysine-head groups. The results are summarized as follows. (1) The enantioselectivity was not observed in the alkaline hydrolysis in chiral micelles only. This matrix possesses no selectivity. When an achiral hydroxamic acid was added to the system,selectivity was induced. (2) The direction of selectivity is reversed by the conformational change of the secondary structure formed by the peptide moiety of matrix micelles. L-Selectivity in the random coil and D-selectivity in the <alpha> -helix condition were observed. (3) The degree of selectivity is dependent on the chemical structure of hydroxamic acid;for example, an N-H type hydroxamic acid gives higher selectivity than an N-methyl type one. Thus, it is supposed that enantioselectivity is introduced by the chiral interaction between chiral micelles and achiral nucleophiles, in which the conformation of polypeptide moiety plays an important role. Less