Biochemical properties of acetyl- and butyrylcholinesterase in human meningioma

Abstract

The structural properties of acetyl- (AChE) and butyrylcholinesterase (BuChE) in meningioma and the possible relationship with brain and plasma were investigated. Meningioma ChEs were extracted with saline and saline-Triton X-100 buffers. The tumor ChE forms were identified by sedimentation analysis, and their amphiphilic/hydrophilic behaviour was assessed by Triton X-114 phase-partitioning and hydrophobic chromatography. Meningioma contained amphiphilic globular AChE dimers (G 2 A) and monomers (G 1 A), and hydrophilic BuChE tetramers (G 4 A). The conversion of G 2 A into G 1 A AChE by reduction confirmed their structures. In contrast to the meningioma species, brain G 1 A AChE forms remained amphiphilic after incubation with alkaline hydroxylamine and phosphatidylinositol-specific phospholipase C (PIPLC). Meningioma G 1 A and PIPLC-converted G 1 H, and brain G 1 A AChE showed similar rate constants for thermal inactivation, and this suggested that the thermal stability of AChE subunits was unaffected by the presence or not of phosphatidylinositol residues. AChE in meningioma and brain did not differ in the interaction with the lectins Con A, LCA, WGA and RCA. BuChE in meningioma and brain bound to a similar extent to Con A, LCA and WGA-Agarose, whereas one-half of BuChE in the tumor, all in plasma and little in brain was fixed by RCA. Therefore, meningioma possesses RCA +- and RCA −-BuChE, the former predominating in brain and the latter in plasma. It remains to be clarified whether the tumor RCA +-BuChE is intrinsic or derived from plasma.