Physics of ProteinsJayanth R. Banavar1 and Amos Maritan21Department of Physics, The Pennsylvania State University, University Park,Pennsylvania 16802; email: jayanth@phys.psu.edu2INFM and Dipartimento di Fisica ‘G. Galilei’, Universit`a di Padova, 35131 Padova,Key Wordstube, geometry, amyloid, marginally compact phase, symmetryAbstractGlobular proteins are a key component of the network of life. Overmany decades much experimental data on proteins have been gathered,yet theoretical progress has been somewhat limited.We showthat the results accumulated over the years inexorably lead to a unifiedframework for understanding proteins. The framework predictsthe existence of a fixed menu of folds determined by geometry, clarifiesthe role of the amino acid sequence in selecting the native-statestructure from this menu, and explains the propensity for amyloidformation. The experimental data and the new approach reveal anastonishing simplicity underlying the protein problem.ContentsINTRODUCTION. . . . . . . . .……