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Scoring protein-protein docked structures based on the balance and tightness of binding
One main issue in protein-protein docking is to filter or score the putative docked structures. Unlike many popular scoring functions that are based on geometric and energetic complementarity, we present a set of scoring functions that are based on the consideration of local balance and tightness of binding of the docked structures. These scoring functions include the force and moment acting on one component (ligand) imposed by the other (receptor) and the second order spatial derivatives of protein-protein interaction potential. The scoring functions were applied to the docked structures of 19 test targets including enzyme/inhibitor, antibody/antigen and other classes of protein complexes. The results indicate that these scoring functions are also discriminative for the near-native conformation. For some cases, such as antibody/antigen, they show more discriminative efficiency than some other scoring functions. such as desolvation free energy (DeltaG(des)) based on pail-wise atom-atom contact energy (ACE). The correlation analyses between present scoring functions and the energetic functions also show that there is no clear correlation between them; therefore, the present scoring functions are not essentially the same as energy functions
In silico study of protein-protein interactions
2011 - 2012Protein-protein interactions are at the basis of many of the most important
molecular processes in the cell, which explains the constantly growing interest
within the scientific community for the structural characterization of protein
complexes.1 However, experimental knowledge of the 3D structure of the great
majority of such complexes is missing, and this spurred their accurate
prediction through molecular docking simulations, one of the major challenges
in the field of structural computational biology and bioinformatics.2,3
My PhD work aims to contribute to the field, by providing novel computational
instruments and giving useful insight on specific case studies in the field. In
particular, in the first part of my PhD thesis, I present novel methods I
developed: i) for analysing and comparing the 3D structure of protein
complexes, to immediately extract useful information on the interaction based
on a contact map visualization (COCOMAPS4 web tool, Chapter 2), and ii) for
analysing a set of multiple docking solutions, to single out the key inter-residue
contacts and to distinguish native-like solutions from the incorrect ones
(CONS-COCOMAPS5 web tool and CONS-RANK program, Chapter 3 and 4,
respectively).
In the second part of the thesis, these methods have been applied, in
combination with classical state-of-art computational biology techniques, to
predict and analyse the binding mode in real biological systems, related to
particular diseases. This part of the work has been afforded in collaboration
with experimental groups, to take advantage of specific biological information
on the systems under study. In particular, the interaction between proteins
involved in the autoimmune response in celiac disease6,7 (Chapters 5 and 6) has
been studied in collaboration with the group directed by Prof. Sblattero,
University of Piemonte Orientale (Italy) and the group directed by Prof.
Esposito, University of Salerno (Italy). In addition, recognition properties of
3
the FXa enzymatic system8 has been studied through dynamic characterization
of a FXa pathogenic mutant that causes problems in the blood coagulation
cascade (Chapter 7). This study has been performed in collaboration with the
group directed by Prof. De Cristofaro, Catholic University School of Medicine,
Rome (Italy) and the group directed by Prof. Peyvandi, Ospedale Maggiore
Policlinico and UniversitĂ degli Studi di Milano (Italy)... [edited by author]XI n.s