İnsan Serum Bütirilkolinesterazı ve Eritrosit Asetilkolinesterazının Statin Türevleri ile Etkileşiminin İncelenmesi

Abstract

To investigate effects of statins on cholinesterases, Butyrylcholinesterase (BChE; E.C.3.1.1.8 ) was purified from human plasma through acid dialysis, DEAE-Tris Acryl M ion exchange and Procainamide-Sepharose 4B chromatography steps. The fold of the process was 867.93. Substrate selectivity of the purified human serum BChE was determined with acetylthiocholine (ATCh), butyrlythiocholine (BTCh), propionylthiocholine (PTCh) and benzoylcholine (BZCh). Inhibition kinetics of statins, atorvastatin, lovastatin, rosuvastatin and simvastatin, with human serum BChE were studied. The ATCh substrate kinetics and inhibition kinetics of the statins, were also analysed with human erythrocyte acetylcholinestrease (AChE; E.C.3.1.1.7). Via Systat 12.0 nonlinear regression analysis, the Km values of purified human serum BChE for the substrates ATCh, BTCh, PTCh and BZCh were found as 216 ± 74, 62 ± 37, 155 ± 40 and, 24 ± 8 μM. Km value of human erythrocyte AChE for ATCh was found as 65 ± 16 μM. BChE Kss values for ATCh, BTCh, and PTCh were found as 2.38 ± 0.39, 1.06 ± 0.47, 4.53 ± 0.45 mM. and the Kcat values of BChE for ATCh, BTCh, PTCh and BZCh were found as; 9.92 ± 0.71, 26.56 ± 8.18, 8.175, 10.56 ± 1.78 x 103 min-1. And their corresponding b values were found as 2.12 ± 0.3, 1.02, 7.49 ± 0.26, 10.78 ± 1.80. The calculated bkcat values of BChE for the ATCh, BTCh, PTCh, BZCh were 21.06, 27.10, 61.23,113.86 x 103 min-1 whereas kcat/km values were found as 45.94, 428.50, 52.74, 0.434 x 104mM-1 min-1. Vm values of BChE for ATCh, BTCh, PTCh and, BZCh; 27.85 ± 2.84, 46.08 ± 3.55, 26.34 ± 2.22,118.73 ± 19.84 μmol-1min.mg.prot, respectively. The IC50 values were of BChE for atorvastatin, lovastatin, rosuvastatin and simvastatin found as 7.24 ± 0.27, 14.20 ± 0.30, 1.03 ± 0.19,17.60 ± 0.09 μM whereas their Ki values were 492.54 ± 55.12, 198.65 ± 27.18, 194.68 ± 55.24 and, 228.91 ± 43.78 μM. Inhibition types of statins on cholinesterses were defined for the first time. Hence, the statins used in this research, were determined as non-competetive inhibitors of human serum BChE. For erythrocyte AChE not all the statins but only Lovastatin was found as an inhibitor.