Before revision:  Our analysis evidences a quite high fraction of chains with a significant linking , that is with |G'| > 1. We report that Nature promotes configurations with G'<0 and surprisingly, it seems to suppress linking of long proteins. While proteins composed of about 100 residues can be well linked in the swapped dimer form, this is not observed for much longer chains. Upon dissociationof a few dimers via numerical simulations, we observe an exponential decay of the linking number with time, providing an additional useful characterization of the entanglement within swapped dimers. Our results provide a novel and robust topology-based classification of protein-swapped dimers together with some preliminary evidence of its impact on their physical and biological properties.
After revision:  Our analysis evidences a quite high fraction of chains with a significant linking , that is with |G'| > 1. We report that Nature promotes configurations with G'<0 and surprisingly, it seems to suppress intertwining in long protein dimers. Supported by numerical simulations of dimer dissociation, our results provide a novel and robust topology-based classification of protein-swapped dimers together with some preliminary evidence of its impact on their physical and biological properties.