The structural modeling of EF-hand motifs in parvalbumin

Parvalbumin (Parv) is a typical protein with EF-hand motifs that play an important role in many physiological processes. We present a novel free energy to model the skeletal C_α chain of the protein from the basic principle of mathematics and physics. Starting from the crystal structure of Parv (PDB code 2PVB), we first analyze the profile of the C_α bond and torsion angles over the segment that contains the secondary structures. Then the parameters in the energy function are evaluated for the helix ABCD fragment that contains two EF-hand domains in Parv. Meanwhile an eight-soliton configuration at the energy minimum is constructed to model the conformation of ABCD fragment. The deviation of the conformation constructed from the model away from the crystal structure is as small as 1.28 Å. The structural modeling stems from the physical energy, which is a benefit relative to the statistics-based or knowledge-based technologies.