In silico enhancement of the stability and activity of keratinocyte growth factor.

Keratinocyte growth factor (KGF), a member of the fibroblast growth factor (FGF) family, has been implicated in some biological processes such as cell proliferation, development and differentiation. High mitogenic activity of this protein has made it very suitable for repairing radiation-and chemotherapy-induced damages. Palifermin, which has been developed from human KGF, is clinically applied to reduce the incidence and duration of cancer therapeutic agents. However, the activity of Palifermin is limited during treatment due to its poor stability. In this study, we have improved the stability and activity of recombinant human KGF (Palifermin) using a computational mutagenesis approach. According to the KGF multiple sequence alignment among different species as well as literature-based information, we have generated several mutations using PyMOL program and evaluated their effects on the stability and activity of KGF in silico. In order to preserve the KGF activity, we did not change the predicted functional residues. Prior to mutagenesis, the 3D structure of rhKGF was predicted by Modeller v9.15 program and quantitative evaluation of predicted models were carried out using VADAR and PROSESS servers. The stability and activity of rhKGF mutants were analyzed using GROMACS molecular dynamics (MD) simulations and docking tools, respectively. The results showed that N159S (N105S in rhKGF sequence) and I172V (I118V in rhKGF) substitutions caused an increased stability and affinity of the rhKGF to Fibroblast growth factor receptor 2 (FGFR2). We will evaluate the effects of favorable mutations on the rhKGF stability and activity in vitro.