title: Role of hydrophobic mutations on the binding affinity and stability of blood coagulation factor VIIIa: a computational molecular dynamics and free-energy analysis.
abstract: Factor VIIIa is a non-covalently bound hetero-trimer among A1, A2 and A3-C1-C2 domains and an essential co-factor for factor IXa enzyme during proteolytic activation of factor X zymogen. The relatively weak interactions between A2 and the interface A1/A3 domains dampen the functional stability of FVIIIa in plasma and results in rapid degradation. We studied the mutational effect of three charged residues (Asp519, Glu665 and Asp666) to several hydrophobic residues by molecular dynamics simulations. Analysis of the binding free energy by MM-PBSA and MM-GBSA methods shows that the mutation of Asp519 and Glu665 residues to either Val or Ala enhance the A2 domain binding affinity in agreement with the experimental site-specific mutagenesis data. Mutation of Asp666 to Val, Tyr, Met and Phe showed largest improvement in the A2-domain binding among the eight hydrophobic mutants studied. Our studies suggest that the enrichment of hydrophobic interactions in the buried surface regions of A2 domain plays crucial role in improving the overall stability of FVIIIa.
authors: Department of Chemistry, North Carolina Agricultural and Technical State University, Greensboro, NC 27411, USA. Electronic address: divi@ncat.edu.
authors: Divi
authors: D
authors: Venkateswarlu
mesh_terms: D001665:Binding Sites; D003198:Computer Simulation; D004355:Drug Stability; D004735:Energy Transfer; D015944:Factor VIIIa / Q000737:chemistry* / Q000235:genetics; D057927:Hydrophobic and Hydrophilic Interactions; D008956:Models, Chemical; D056004:Molecular Dynamics Simulation; D016297:Mutagenesis, Site-Directed; D011485:Protein Binding; D011487:Protein Conformation; D013329:Structure-Activity Relationship; D013816:Thermodynamics
chemical_list: D015944:Factor VIIIa
keywords: Binding free-energy; Factor VIIIa; Hemophilia-A; MM-PBSA; Molecular dynamics