Abstract
Both turkey (TPL) and chicken (CPL) pancreatic lipases possess only one exposed sulfhydryl residue (Cystein114). After preincubation with the lipase, the sulfhydryl reagent C
12-TNB was found to be a powerful inhibitor of TPL whereas it had no effect on the CPL activity. Based on the 3D structure modelling and the molecular dynamics, the bulky dodecyl chain might hamper the lid movement of the TPL leading to the lipase inhibition upon reaction with C
12-TNB. Meanwhile, the predicted position of the C
12 chain linked to Cystein114 of CPL could not block the lid opening mechanism which explains the absence of inhibition by C
12-TNB. Surprisingly, when added during the substrate hydrolysis, C
12-TNB activated the TPL but not the CPL that was slightly inhibited under these conditions. The 3D structure model generated for the open forms of C
12-TPL and C
12-CPL complexes showed that Cystein114 is still accessible and might react with C
12-TNB. Our models clearly explain the activation of TPL and the partial inhibition of CPL after the binding of the C
12 chain to the enzyme.