Macromolecular Self-Assembly of Diketopiperazine Tetrapeptides
摘要:
Basic solutions of tetrapeptides derived from L-aspartic acid diketopiperazines are shown to form microcapsules when acidified to pH 2.4. An initial structure-activity study clearly demonstrates that a very delicate balance exists between the tetrapeptides' structure and their ability to self-assemble. Scanning electron micrographs confirm that microcapsules and not solid microspheres are formed.
Copper(II) complexes with cyclo(L-aspartyl-L-aspartyl) and cyclo(L-glutamyl-L-glutamyl) derivatives and their antioxidant properties
作者:Raffaele P. Bonomo、Enrico Conte、Giuseppe Impellizzeri、Giuseppe Pappalardo、Roberto Purrello、Enrico Rizzarelli
DOI:10.1039/dt9960003093
日期:——
Two new functionalized cyclodipeptides have been synthesized with the aim of obtaining a good model of superoxide dismutase. Better to mimic the active site of this metalloenzyme, these two compounds have been designed to allow a great co-ordination flexibility. Copper(II) complexes with cyclo(-L-aspartyl-L-aspartyl-) or cyclo(-L-glutamyl-L-glutamyl-)bis(histamine)(L) have been thermodynamically and spectroscopically characterized and their antioxidant activity tested against enzymatically generated O2–. Taking into account the speciation of the system, it has been determined that the more active species against O2– is the [CuL2]2+ complex. Electron spin resonance measurements suggest for this species the presence of four imidazole nitrogen atoms in a slightly tetrahedrally distorted co-ordination plane. The [CuLH–2] complex species also possesses four-nitrogen co-ordination involving two deprotonated peptide nitrogen atoms. The complex [CuL2]2+ showed the highest antioxidant activity and reasons for this behaviour are proposed on the basis of spectroscopic and voltammetric data.
Macromolecular Self-Assembly of Diketopiperazine Tetrapeptides
作者:Raymond J. Bergeron、Otto Phanstiel、Guo Wei Yao、Sam Milstein、William R. Weimar
DOI:10.1021/ja00098a007
日期:1994.9
Basic solutions of tetrapeptides derived from L-aspartic acid diketopiperazines are shown to form microcapsules when acidified to pH 2.4. An initial structure-activity study clearly demonstrates that a very delicate balance exists between the tetrapeptides' structure and their ability to self-assemble. Scanning electron micrographs confirm that microcapsules and not solid microspheres are formed.