cefuroxime-axetil and physostigmine-salicylate

An esterase which hydrolyses the cephalosporin antibiotic, cefuroxime axetil has been isolated from rat intestinal washings and purified. Closely related cefuroxime esters were extremely poor substrates, but p-nitrophenyl acetate and alpha-naphthyl acetate were slowly hydrolysed by the purified enzyme. Analysis by gel filtration gave an Mr = 51,000 and on SDS-polyacrylamide gel electrophoresis the esterase resolved into two main bands of Mr = 31,500 and 26,800. Analytical isoelectric focusing resolved purified esterase into multiple forms active toward alpha-naphthyl acetate, the isoelectric points of which ranged from pH 4.5 to 6.3. The esterase bound specifically to Con A-Sepharose suggesting it could be a glycoprotein. Esterase activity was unaffected by the presence of dihydroxy bile salts (1-8 mM) and inhibition studies using organophosphates and eserine salicylate have classified the enzyme as a carboxylesterase.

Topics: Animals; Bile Acids and Salts; Carboxylic Ester Hydrolases; Cefuroxime; Cephalosporins; Dogs; Humans; Intestine, Small; Isoelectric Focusing; Isoflurophate; Male; Naphthols; Phenylmethylsulfonyl Fluoride; Physostigmine; Rats; Species Specificity; Substrate Specificity