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Abstract
Lens esterase I was purified 23 times from normal lenses to apparent homogeneity as judged by chromatography on DEAE Sephadex and isoelectric focusing. Optimum rates of hydrolysis were observed at pH 6.8. The substrates of choice were α-naphthyl acetate, butyrate, caproate, caprylate, and β-propionate. The esterase shows an isoelectric point of 5.1 and a Km value of 0.095 mM with a-naphthyl acetate at pH 6.8. Enzymic activity was stimulated by the addition of either Ca+2 or Mn+2. The hydrolysis of substrates was inhibited by EDTA, phenylmethylanesulphonyl fluoride, p-hydroxy mercuribenzoate, diisopropylfiuorophosphate, diethyl-β-nitrophenyl phosphate, and urea.