Attractors in residual interactions explain the differentially-conserved   stability of Immunoglobulins
  Proteins belonging to immunoglobulin superfamily(IgSF) show remarkably conserved nature both in their folded structure and in their folding process, but they neither originate from very similar sequences nor demonstrate functional conservation. Treating proteins as fractal objects, without studying spatial conservation in positioning of particular residues in IgSF, this work probed the roots structural invariance of immunoglobulins(Ig). Symmetry in distribution of mass, hydrophobicity, polarizability recorded very similar extents in Ig and in structurally-closest non-Ig structures. They registered similar symmetries in dipole-dipole, {\pi}-{\pi}, cation-{\pi} cloud interactions and also in distribution of active chiral centers, charged residues and hydrophobic residues. But in contrast to non-Ig proteins, extents of residual interaction symmetries in Ig.s of largely varying sizes are found to converge to exactly same magnitude of correlation dimension - these are named 'structural attractors', who's weightages depend on ensuring exact convergence of pairwise-interaction symmetries to attractor magnitude. Small basin of attraction for Ig attractors explained the strict and consistent quality control in ensuring stability and functionality of IgSF proteins. Low dependency of attractor weightage on attractor magnitude demonstrated that residual-interaction symmetry with less pervasive nature can also be crucial in ensuring Ig stability. 
Anirban Banerji
q-bio.BM