Modulating the activity of avian pancreatic lipases by an alkyl chain reacting with an accessible sulfhydryl group.
Both turkey (TPL) and chicken (CPL) pancreatic lipases possess only one exposed sulfhydryl residue (Cystein114). After preincubation with the lipase, the sulfhydryl reagent C12 -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 C12 -TNB. Meanwhile, the predicted position of the C12 chain linked to Cystein114 of CPL could not block the lid opening mechanism which explains the absence of inhibition by C12 -TNB. Surprisingly, when added during the substrate hydrolysis, C12 -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 C12 -TPL and C12 -CPL complexes showed that Cystein114 is still accessible and might react with C12 -TNB. Our models clearly explain the activation of TPL and the partial inhibition of CPL after the binding of the C12 chain to the enzyme.
Fendri
Ahmed
A
Laboratoire de Biochimie et de Génie Enzymatique des Lipases, ENIS route de Soukra, BPW 3038 Sfax, Tunisia.
Frikha
Fakher
F
Miled
Nabil
N
Ben Bacha
Abir
A
Gargouri
Youssef
Y
D000818:Animals; D002645:Chickens; D004789:Enzyme Activation; D007202:Indicators and Reagents / Q000737:chemistry; D008049:Lipase / Q000737:chemistry / Q000378:metabolism*; D010179:Pancreas / Q000201:enzymology*; D013438:Sulfhydryl Compounds / Q000737:chemistry*; D014422:Turkeys
D007202:Indicators and Reagents; D013438:Sulfhydryl Compounds; D008049:Lipase