EFFECTS OF GLUTAMINES ON THE SELF-ASSEMBLY OF A BETA-HAIRPIN FIBRILS

点击翻译按钮获取中文摘要

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Amyloid fibrils, well-structured aggregates of misfolded protein, have been implicated in a number of prevalent human diseases such as Alzheimer's dementia and Creutzfeldt-Jacob's disease. While formed by a diverse repertoire of proteins and synthetic peptides, including many with glutamine-rich sequences, amyloid fibrils have a common cross-beta-structure. Even with this common arrangement and multiple models for the atomic structure of glutamine-rich amyloid, a dominant set of forces governing amyloid formation and stabilization have not been experimentally determined. Since the forces previously investigated have not included side-chain hydrogen bonding, we created a glutamine-rich model system by de novo design that is capable of these interactions. This model, in a disulfide-cyclized form, forms beta-sheet structures, as shown by circular dichroism, and exhibits a fibril morphology, as shown by atomic force microscopy. ATR-FTIR spectroscopy was used to determine the degree of polymerization of these peptides by monitoring the presence of a sharp vibrational band resulting from aggregation effects. Through the incorporation of multiple lysine residues, it is hoped that the kinetics of folding and polymerization involved in fibril formation can be controlled via changes in salt and pH and will facilitate the study of the early intermediates of this process. Future investigation using variations on this new model system will allow the determination of the importance of glutamine side-chain hydrogen bonding in fibril growth and stability.