Synthesis of Silica Forming Phosphoproteins

点击翻译按钮获取中文摘要

Efficient preparative methods of organic chemistry are key to synthesize longer long-chain polyamines (LCPA) and highly modified phosphopeptides like silaffin1-A1 which bears posttranslational modifications on 11 out of 15 amino acids. To this end we will expand the applicability of the Borrowing Hydrogen strategy for the synthesis of LCPA and oligoamine-extended Lysine. The polycationic target molecules will be studied subsequently in biomimetic silica precipitation experiments in collaboration with other groups of the Research Unit. Synthetic (LCPA) and polycationic peptides equipped with site-specific labels are a valuable source of information in the analysis of amorphous silica. The NMR isotope labels at different carbons and nitrogen positions along the LCPA chain measure the distance between the LCPA molecule and the closest silicon atom at the phase boundary between organic and inorganic components of the precipitated silica. These experimental relaxation data are then compared with Si-N distances from modeling experiments. NMR competition experiments are able to rank the silica precipitation properties of the synthetic molecules. The further development of our solution NMR methods for the tracking of silica precipitation experiments with the polybasic compounds are another objective of this project. Solution NMR as a fast, quantitative, and reliable method to follow the silica precipitation process. Furthermore, NMR is able to differentiate gelation from silica precipitation and it will be employed in the search of supposed Si-organic complexes which may occur transiently between LCPA and orthosilicic acid in solution.