Analysis of Apparent Catalytic Parameters of Multiple Molecular Forms of Human Plasma Butyrylcholinesterase by Activity Gel-Scanning Following Non-denaturing Electrophoresis

Butyrylcholinesterase (BChE) in human plasma is composed of four molecular forms: C1 (monomer); C2, covalent conjugate between BChE monomer and albumin; C3, dimer; and C4, tetramer, the major form. Catalytic parameters of molecular forms were estimated at high substrate concentration after non-denaturing polyacrylamide gel electrophoresis by activity gel-scanning densitometry, using a chromogenic substrate (butyrylthiocholine (BTC)). Though catalytic parameters Kss (dissociation of enzyme substrate complex at high substrate concentration) and catalytic constants are apparent (phenomenological) parameters, results indicate that the four molecular forms of human BChE do not display significant differences in their catalytic behavior at high BTC concentration.