Helix-Coil Transition Signatures B-Raf V600E Mutation and Virtual Screening for Inhibitors Directed Against Mutant B-Raf.

BACKGROUND: Mutation in the B RAF at V600E has been well implicated in the carcinogenesis that makes it as an attractive therapeutictarget. In the present study, we sought to identify the basis of V600E mutation at functional and structural grounds. The study also endeavors in identification of small molecule as a potential candidate with considerable pharmacological profile than available BRAF inhibitors through computational approaches. METHODS: The functional effects of V600E mutation was predicted using SIFT and Polyphen servers. Protein structural alterations werepredicted using SDM server and RMSD calculations. Virtual screening was performed considering existing BRAF inhibitors viz., Vemurafenib, Sorafenib, Dabrfenib, Trametinibthat formed query compounds for shape similarity search by Tanimoto similarity indices with a threshold of 95%. Compound with high affinity as similar to query compound was retrieved and screened for its ADMET properties. RESULTS: The SNP was shown to be highly vulnerable to malfunction and have damaging effects. Mutated protein showed that the secondary structure was irregular and side chain hydrogen bonds were unsaturated. The superimposition of wild onto mutated V600E BRAF revealed helix-coil transition occurring wherein residues Val 502, Leu 505, Arg506, Lys 507 assumed coiled conformation in the mutated BRAF. Virtual screening led to identification of SCHEMBL298689 akin to Vemurafenib as high affinity B-Raf inhibitors; with least toxicity and optimal bioactivity. CONCLUSION: In the present investigation, we put forth the structural and functional basis of B RAF V600E mutation showing helix coil transitions. In addition identified high affinity compound targeting V600E B RAF through virtual screening.

Computer aided identification of sodium channel blockers in the clinical treatment of epilepsy using molecular docking tools.

UNLABELLED: Phenytoin (PHT) and Carbamazepine (CBZ) are excellent sodium channel blockers administered in clinical treatment of epileptic seizures. However, the narrow therapeutic range and limited pharmacokinetics of these drugs have raised serious concerns in the proper management of epilepsy. To overcome this, the present study attempts to identify a candidate molecule with superior pharmacological profile than PHT and CBZ through In silico approaches. PHT and CBZ served as query small molecules for Tanimoto based similarity search with a threshold of 95% against PubChem database. Aided by MolDock algorithm, high affinity similar compound against each query was retrieved. PHT and CBZ and their respective similar were further tested for toxicity profiles, LC 50 values and biological activity. Compounds, NSC403438 and AGN-PC-0BPCBP respectively similar to PHT and CBZ demonstrated higher affinity to sodium channel protein than their respective leads. Of particular relevance, NSC403438 demonstrated highest binding affinity bestowed with least toxicity, better LC 50 values and optimal bioactivity. NSC403438 was further mapped for its structure based pharmacophoric features. In the study, we report NSC403438 as potential sodium channel blocker as a better candidate than PHT and CBZ which can be put forth for pharmacodynamic and pharmacokinetic studies. ABBREVIATIONS: AEDs - Antiepileptic drugs, BLAST - Basic Local Alignment Search Tool, CBZ - Carbamazepine, GEFS+ - Generalized Epilepsy with Febrile Seizures Plus, GPCR - G Protein Coupled Receptor, Nav - Sodium channel with specific voltage conduction, PDB - Protein Data Bank, PHT - Phenytoin, PIR - Protein Information resources, SAVES - Structural Analysis and Verification Server, VGSC - Voltage-gated Sodium channels.