Structural analysis and inhibitory kinetics of brain type creatine kinase by sodium dodecyl sulfate.

The studies regarding the effect of sodium dodecyl sulfate (SDS) on enzyme activities and structures can provide a valuable insight into public health. We have predicted the 3D structure of the brain creatine kinase (CK-BB) with a high resolution and simulated the docking between CK-BB and SDS. The predicted structure had a root mean square deviation of 0.51 A. The docking between CK-BB and SDS was successful with significant scores (-4.67 kcal/mol, AutoDock4 and -48.32 kcal/mol, DOCK6). We have also investigated the inactivation by using SDS to study CK-BB's folding behaviors. The two-phase rate constants as a first-order reaction were measured during inactivation. SDS strongly inhibited the CK-BB activity in a noncompetitive inhibition manner (K (i) = 1.22 mM). The tertiary structural change was induced by SDS binding with the exposure of hydrophobic surface. The methyl-beta-cyclodextrin was used to strip SDS from the enzyme molecule to reactivate. The changes of thermodynamic parameters for the SDS ligand binding such as enthalpy, Gibbs free energy, and entropy were obtained as -13 + or - 7.0 MJ/mol, 8.39 kJ/mol, and -42.754 kJ/(K mol), respectively. Our study provides important structural information for CK-BB and its interaction with SDS with an insight on its folding and inhibition kinetics.