Neuroinformatics analyses reveal GABAt and SSADH as major proteins involved in anticonvulsant activity of valproic acid

• Human GABAt model was generated based on pig GABAt (PDB 1OHV) template and was submitted to Protein Model Database.
• GABAt and SSADH were predicted to have allosteric and competitive inhibition by VPA by molecular docking studies.
• Inhibition constant (Ki) of VPA for all studied enzymatic receptors except α-KGDH is predicted observed well below the therapeutic range in blood.
• VPA predicted to favour GABAergic over glutamatergic mode of anticonvulsant activity.

The unequivocal hypotheses about anticonvulsant activity of valproic acid (VPA) have always been a basic hurdle in designing next generation neurotherapeutics, particularly the anti-epileptic drugs. The present study reports about a comprehensive in-silico investigation into qualitative and quantitative binding of VPA and corresponding natural ligands of four major enzymes involved in neurotransmissions, namely—GABA transaminase (GABAt), α-keto glutarate dehydrogenase (α-KGDH), Succinate Semialdehyde dehydrogenase (SSADH) and Glutamate Decarboxylase (GAD), respectively. The molecular docking analyses revealed that VPA inhibits GABAt and α-KGDH through allosteric while SSADH through competitive mode of binding. There is an observed elevation in binding of glutamate over GAD in the presence of VPA. The docking inhibition constant (Ki) of VPA to all the studied enzymatic receptors were observed to be well below the therapeutic concentration of VPA in blood, except for α-KGDH, thus favouring GABAergic over glutamatergic mode of anticonvulsant activity of VPA. The report is probably the first comprehensive in-silico molecular study about VPA action.

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