Poly(Styrene-Maleic Acid) stabilized lipid nanodiscs offer enormous potential as tools for membrane structural biology and biophysics. Polymer stabilized nanodiscs have a number of attractive characteristics including ease of preparation and low cost. In this proposal we wish to systematically study two membrane proteins, Gramicidin and ZipA supported in our discs. Gramicidin is a commercially available, membrane spanning beta-helix forming peptide which will be used to undertake a systematic study into protein loading in the nanodiscs as concentration of the peptide is increased. ZipA is a membrane protein which has a single transmembrane domain and forms monomers, dimers or tetramers in the discs, but the membrane bound structure is not known. This systematic study will enable us to test polymer-nanodiscs as protein supports for structure determination.