Abstract
Covalently circularized nanodiscs (cNDs) represent a significant advance in the durability and applicability of nanodisc technology. The new cNDs demonstrate higher size homogeneity and improved stability compared with that of non-circularized forms. Moreover, cNDs can be prepared at various defined sizes up to 80-nm diameter. The large cNDs can house much larger membrane proteins and their complexes than was previously possible with the conventional nanodiscs. In order to experience the full advantages of covalent circularization, high quality circularized scaffold protein and nanodisc samples are needed. Here, we give a concise overview and discuss the technical challenges that needed to be overcome in order to obtain high quality preparations. Furthermore, we review some potential new applications for the cNDs.