We present a first principle density functional study of phenylalanine interacting with three different classes of surfaces, namely a purely repulsive hard wall, mildly interacting close packed surfaces of group 11 metals (Cu(1 1 1), Ag(1 1 1), and Au(1 1 1)), and strongly interacting close packed surfaces of group 10 metals (Ni(1 1 1), Pd(1 1 1), and Pt(1 1 1)). In particular, we characterize, by changing the substrate, the passage from the statistical behavior of a flexible molecule in the presence of the topological confinement of a hard wall to a purely chemical behavior where the molecule, highly deformed compared to the free state, strongly binds to the surface and statistical conformations play no longer a role. Such a comparative study allows for characterization of some of the key aspects of the adsorption process for a prototype of flexible amino acids on experimentally and technologically relevant metal surfaces.