Generation of wild-type rat Glucocerebrosidase homology modeling: Identification of putative interactions site and mechanism for chaperone using combined in-silico and in-vitro studies.

ABSTRACT

Disease-modifying treatment strategy for Parkinson's disease (PD) by stabilization of Glucocerebrosidase (GCase) enzyme by chaperones is of particular interest. Wild-type rat is a widely used animal model for PD; however, the in-silico model to elucidate the nature of rat GCase (rGCase)-chaperone interactions, mechanisms, and structural stability is still unavailable. Hence, we have developed pH-dependent rGCase homology models, in-silico (docking and molecular dynamics), and in-vitro techniques (enzyme kinetics and thermal stability) to address this gap. The homology modeling results revealed ≥ 90% rGCase residues were in the favored regions, representing adequate models quality. In-silico studies showed an interaction between chaperone (Ambroxol, AMB) and the active site residues TYR 331, TYR 263, GLN 266, and GLU 358 with the higher affinity at neutral pH than acidic pH. In-vitro studies showed higher inhibitory activity (IC50) and binding affinity (Ki) of AMB at neutral pH (IC50 8.2 ± 2.6 µM and Ki 4.3 ± 1.2 µM) than acidic pH (IC50 and Ki not identified). AMB improved rGCase thermostability was confirmed by thermal denaturation assay. We have developed the homology model for rGCase, which provides a perspective for designing and screening the chaperones at the initial phases of drug discovery to ameliorate PD.