The clinical efficacy of the blood coagulation cofactor VIIIa, a non-covalently bound hetero-trimer among the A1, A2 and A3-C1-C2 domains, critically depends on the A2-domain binding affinity with A1/A3 interface domains. The relatively weak interactions between the A2 and the interface A1/A3 domains are largely attributed for the unstable nature of FVIIIa due to rapid dissociation of the A2 domain in blood. In this work, computational MD simulations and MM-PBSA based binding free-energy analysis methods were employed to assess the structural and energetic impact of singe-point mutations on several polar or charged residues that appear at the interface of A2/A1 and A2/A3 domains in effort to identify the ideal mutational hot-spot residues that could improve the A2-domain binding affinity. The interface residues that were investigated are Ser268, Asp519, Gln645, Thr646 and Glu665. Each of these residues was mutated to fourteen non-charged amino acids and the binding affinity of A2 domain with A1/A3 interface was estimated based on the MD equilibrated solution structures. Our study predicts that mutation of some of these residues with hydrophobic amino acids improve the binding affinity as much as 15 Kcal/mol. This study highlights the significance of reducing the polar interactions and enhancing the hydrophobic character of the domain-domain interfaces of FVIII in promoting the overall thermal stability of FVIIIa.<br/>

Mutational analysis of A2-domain interface residues in promoting the structural stability of blood coagulation factor vIIIa: A computational binding free-energy analysis study

255th National Meeting (2018)

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