CHARACTERIZATION OF ACETYLCHOLINESTERASE AND ITS MOLECULAR-FORMS IN ORGANS OF 5 FRESH-WATER TELEOSTS

The activity and molecular forms of acetylcholinesterase (AChE, EC 3.1 .1.7) were characterized in the brain, heart, white skeletal muscle an d liver of the Siberian sturgeon (Acipenser baeri), European eel (Angu illa anguilla), wels (Silurus glanis), common carp (Cyprinus carpio) a nd silver carp (Hypophthalmichthys molitrix), belonging in four famili es. The brain had the highest (between 183.2+/-10.6 and 1361.2+/-189.7 mU mg(-1) protein and between 4.7+/-0.4 and 23.5+/-2.7 U g(-1) wet ti ssue) and the liver the lowest (between 25.3+/-1.9 and 126.5+/-22.7 mU mg(-1) protein and between 1.0+/-0.1 and 4.5+/-0.5 U g(-1) wet tissue ) activity in all these fish, with the exception of the wels, where th e heart contained the smallest amount of AChE (26.2+/-7.5 mU mg(-1) pr otein and 1.2+/-0.3 U g(-1) wet tissue). The highest tissue AChE activ ity was found in the carp and lowest in the sturgeon. The solubility p roperties and molecular forms of AChE in the four tissues were studied by extraction in high-salt medium (1.0 M NaCl) with and without the d etergent Triton X-100 (0.5%, v/v). The proportions of detergent-solubl e (DS) and salt-soluble (SS) forms of AChE varied considerably from on e species to another, but a general tendency could be observed: the pr oportion of DS AChE was generally higher in the brain (between 70.4+/- 4.1 and 82.5+/-1.2%) and lower in the heart (between 12.0+/-2.0 and 51 .3+/-2.3%) and skeletal muscle (between 16.0+/-2.0 and 64.4+/-0.7%). V elocity sedimentation centrifugation revealed that most tissues contai ned the G(4) or A(4) form. Three tissues (brain, heart, and liver) of the Siberian sturgeon contained a relatively high proportion of the G( 1) form (between 24.3+/-2.4 and 28.6+/-4.9%), while the skeletal muscl e of the wels contained only the most complex type of AChE, i.e., A(12 ). Amongst the tissues studied, the brain and liver mostly contained a mphiphilic globular forms of the G(4) type, while the heart and skelet al muscle were rich in asymmetric forms (A(4) and A(12)). It was concl uded that the differences revealed in the activities of AChE and in th e distribution of its molecular forms may be connected with the variat ion in behavioral habits (feeding and swimming patterns), and the deve lopmental stage of the nervous system.