... proteases: structure and mechanism of catalysis. Annu. Rev. Biochem. 46, 331–358.43. Blow, D.M., Birktoft, J.J. & Hartley, B.S. (1969) Role of a buried acid group in the mechanism of action of ... of action of anticholinesterases. Phar-macol. Ther. 6, 579–628.33. Fersht, A. (1999) Structure and Mechanism in Protein Science,pp. 172–173. W.H. Freeman, San Francisco.34. Selwood,T.,Feaster,S.R.,States,M.J.,Pryor,A.N.&Quinn,D.M. ... Chlorpyrifos-oxon concentration wasstandardized against wild-type BuChE of known concen-tration.Enzyme assayInitial rate of turnover of BTC was measured by the method of Ellman et al.[21]in0.1Msodium...