Morphology of Human Cystatin C Oligomers - Towards the Construction of Hcc Nanodetector

Abstract

Human cystatin C (HCC) is a commonly known inhibitor of cysteine proteases and also macromolecule used as a marker in the clinical diagnosis of the kidney function. This protein exhibits a strong tendency to misfolding via the domain swapping mechanism and then it is able to form oligomers, fibrils and amyloid deposits that can be built in brain blood vessels. The aim of our study was precise characterisation of morphology of these oligomers obtained in various conditions. Different types of HCC oligomers and aggregates were generated using native cystatin C and its covalently stabilised variant. These HCC oligomer species were generated in different compositions of solution, pH values, ionic strength, and also using various temperature and agitation conditions. The micromorphology of obtained HCC aggregates and oligomers was described on the basis of electron microscopy images and topographic data from the atomic force microscopy. In parallel the process of oligomer formation was characterised using 1H NMR diffusometry. In the next step, these HCC oligomers were selected as targets for nanosensing studies. At this stage, preliminary construction studies of a nanosensor selective for detection of HCC variants were initiated. For this research stage the initial immobilisation protocol of antibodies, selective to HCC oligomers, on the gold nanoparticles was tested. The work was supported by the grant POLTUR2/3/2017 from National Centre for Research and Development (Poland) and grant 117Z009 from TÜBİTAK (Turkey).