An Investigation of the Impact of Molecular Geometry upon Microcapsule Self-Assembly
摘要:
Bis-amide dicarboxylic acids derived from the condensation of malonic acid, 1,1-dimethylmalonic acid, 1,1-cyclopropane dicarboxylic acid, or maleic acid with L-phenylalanine, (L-Phe), are shown to supramolecularly self-assemble in aqueous solution. When basic solutions of these diacids are taken to pH 2.4, microcapsules are formed. Scanning and transmission electron micrographs confirm that microcapsules and not solid microspheres are generated. The ability of these assemblies to encapsulate other materials present during their formation in water was demonstrated with a tannic acid marker. Structure-activity studies clearly demonstrate the importance of a cis geometry between L-Phe fragments for self-assembly. Molecular modeling revealed that the cis geometry of 1a, 5a, and 14 imparts a helical structure to these systems. The subsequent self-association via hydrogen bonds of these hydrophobic helical diacids is postulated as the mechanism for their self-assembly, Nonmicrocapsule forming scaffolds (predicated on oxalic, fumaric, and succinic acid backbones) favored ''cuplike'' or pocket geometries which were not conducive to intermolecular aggregation.
Synthesis of symmetrical pseudopeptides as potential inhibitors of the human immunodeficiency virus-1 protease
摘要:
It is demonstrated that HIV-1 protease is essential for the assembly and infectivity of the acquired immunodeficiency syndrome (AIDS) virus. This protease is an aspartyl protease with a 2-fold symmetry axis. Potential inhibitors were synthesized and consisted of a spacer linking 2 peptidic chains. They had to satisfy the following constraints: a C-2 symmetry axis, a backbone similar to the peptidic substrates, and side-chains filling the subsites S-n...S'(n). The compounds were synthesized via peptidic synthetic methods and evaluated in an enzymatic test with HIV-1 protease. Several compounds displayed an inhibitory activity at 10 mu M. They possessed the spacers CO, CO-CO, CO-CH2-CHOH-CO and the terminal chain Phe-O-iC(4)H(9). However, the structural-variation-based optimization of these different compounds failed and no potent inhibitors were prepared.