BIOCHEMICAL-PROPERTIES OF ACETYLCHOLINESTERASE AND BUTYRYLCHOLINESTERASE IN HUMAN MENINGIOMA

The structural properties of acetyl-(AChE) and butyrylcholinesterase ( BuChE) in meningioma and the possible relationship with brain and plas ma were investigated. Meningioma ChEs were extracted with saline and s aline-Triton X-100 buffers. The tumor ChE forms were identified by sed imentation analysis, and their amphiphilic/hydrophilic behaviour was a ssessed by Triton X-114 phase-partitioning and hydrophobic chromatogra phy. Meningioma contained amphiphilic globular AChE dimers (G(2)(A)) a nd monomers (G(1)(A)), and hydrophilic BuChE tetramers (G(4)(H)). The conversion of G(2)(A) into G(1)(A) AChE by reduction confirmed their s tructures. In contrast to the meningioma species, brain G(1)(A) AChE f orms remained amphiphilic after incubation with alkaline hydroxylamine and phosphatidylinositol-specific A phospholipase C (PIPLC). Meningio ma G(1)(A) and PIPLC-converted G(1)(H) and brain G(1)(A) AChE showed s imilar rate constants for thermal inactivation, and this suggested tha t the thermal stability of AChE subunits was unaffected by the presenc e or not of phosphatidylinositol residues. AChE in meningioma and brai n did not differ in the interaction with the lectins Con A, LCA, WGA a nd 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 i n plasma and little in brain was fixed by RCA. Therefore, meningioma p ossesses RCA(+)- and RCA(-)-BuChE, the former predominating in brain a nd the latter in plasma. It remains to be clarified whether the tumor RCA(+)-BuChE is intrinsic or derived from plasma.