. The Biological bulletin. Biology; Zoology; Marine biology. CHARACTERIZATION OF A POLYCHAETE CHOLINESTERASE 399 Table I Specific CliE activity (nmol/min/mg protein) in soluble fractions of Nereis diversicolor and Eisenia fetida with various substrates (A TCIi. PrTCh. and BuTCh) Specific acti vity (n mol/min /mg protein) Species ATCh PrTCh BuTCh N. diversicolor E. fetida ± ± ± ± ± ± Kinetic measurements were performed at 20°C in 300^1 of M phosphate buffer (pH ) added with 20 ii\ of M DTNB, 20 m1 of A/substrate (ATCh,
. The Biological bulletin. Biology; Zoology; Marine biology. CHARACTERIZATION OF A POLYCHAETE CHOLINESTERASE 399 Table I Specific CliE activity (nmol/min/mg protein) in soluble fractions of Nereis diversicolor and Eisenia fetida with various substrates (A TCIi. PrTCh. and BuTCh) Specific acti vity (n mol/min /mg protein) Species ATCh PrTCh BuTCh N. diversicolor E. fetida ± ± ± ± ± ± Kinetic measurements were performed at 20°C in 300^1 of M phosphate buffer (pH ) added with 20 ii\ of M DTNB, 20 m1 of A/substrate (ATCh, PrTCh, or BuTCh), and 10 mI of tissue extracts. The reaction rate was monitored by the increase in absorbance at 410 nm as a function of time. Data are means ± SD. Localization ofChE activity in the body S extracts from the anterior part (head) of A^. diversicolor possess a specific activity at least twofold higher than those from the body region (Table II). By contrast, S extracts from the same two parts of E. fetida have the same specific activities. Sequential extraction ofChEs A similar procedure was used to determine the relative activities of the soluble enzymes (S) and the enzymes bound to membranes (DS). In A^. diversicolor, most of the AChE activity was recovered from the soluble fraction (95% in S versus 5% in DS); and a similar result was ob- tained for the PrChEs of E. fetida (80% in S versus 20% in DS) (Fig. 3). Electrophoretic analysis ofChEs Based on the localization of ChEs, an electrophoresis study was conducted with S extracts or "direct DS" ex- tracts from jV. diversicolor heads and from E. fetida whole bodies. Neither the original Kamovsky and Roots method nor one modified by increasing the pH to revealed any ChE activity in A^. diversicolor samples. A weak re- action was obtained with the original procedure of Koelle and Friedenwald, and rather good results were obtained when the pH was raised to In E. fetida, the two meth- ods a
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