Chemistry is an experimental science, Product Details of 617-45-8, and the best way to enjoy it and learn about it is performing experiments.Introducing a new discovery about 617-45-8, Name is DL-Aspartic Acid, molecular formula is C4H7NO4, belongs to amides-buliding-blocks compound. In a document, author is An, Lin.
Cyclic dipeptide (CDP) is a kind of the smallest cyclic peptide with two amino acids cyclization through amide bonds. The two amide bonds with four hydrogen bonding sites give CDPs a high self-assembly propensity, mainly driven by the hydrogen bonding interactions. In this paper, we have designed four CDPs, c-SF, c-SY, c-SH and c-DF, and studied their self-assembly performance in aqueous solution with circular dichroism spectroscopy (CD) and atomic force microscopy (AFM), including the effects of pH and zinc ion coordination on self-assembly. The fluorescence properties of CDP self-assemblies have also been studied. CD results showed that c-SF, c-SY and c-DF adopted a beta-sheet conformation, while c-SH was random coil secondary structure at the concentration of 2.0 mmol/L and pH 5.0. AFM results showed that c-SF, c-SY and c-DF could form nanofibers with different diameters ranged from 1.0 to 3.0 nm. In addition, c-SY self-assembled hierarchically over time. Not only the nanofiber diameter gradually increased, but also the nanofibers entangled into 3D networks. Although c-SH did not self-assemble at the concentration of 3.0 mmol/L and pH 7.0, it could form monolayers with the induction of zinc ion at pH 9.0. The self-assemblies of each CDP had different multiple fluorescent emission peaks with excitation of different wavelengths. Especially, c-SF emitted green fluorescent light under UV light of 365 nm. The fluorescent emission intensity of CDPs was much stronger than their corresponding linear dipeptides. It was assumed that the diketopiperazine structure contributed to the fluorescence enhancement. Moreover, the fluorescent emission intensity of CDP self-assemblies was much higher than that of their free molecules, which meant that the ordered aggregation made a significant contribution to the fluorescent properties. Both the coordination of zinc ions with the imidazole groups on histidine and the oxidation of phenolic hydroxyl groups in tyrosine could enhance the fluorescent emission intensity of CDPs. It was assumed that CDP molecules stacked one by one to form nanofibers during self-assembly. The diketopiperazine ring of CDPs and its self-assembly endowed CDPs with special fluorescent properties.
Sometimes chemists are able to propose two or more mechanisms that are consistent with the available data. If a proposed mechanism predicts the wrong experimental rate law, however, the mechanism must be incorrect.Welcome to check out more blogs about 617-45-8, in my other articles. Product Details of 617-45-8.
Reference:
Amide – Wikipedia,
,Amide – an overview | ScienceDirect Topics