Characteristics of acid phosphatase in Porcellio laevis Laterille (Porcellionidae, Isopoda)

Abstract

1.1. Cellulose acetate electrophoretic pattern studies on the haemolymph acid phosphatase revealed the presence of two isozymes. The energy of activation for hydrolysis of disodium p-nitrophenyl phosphate amounted to 8200± 100 cal/mole.2.2. Inhibition by diisopropylfluorophosphate and sodium cyanide ranged from 50–79·5 per cent, while by trinitrobenzene sulphonic acid and sodium bisulphite inhibition was 25–43 per cent.3.3. Inhibition of the enzyme by EDTA, except in the presence of Mg2+ and Zn2+, gives it the status of metalloenzyme.4.4. l-Tyrosine effectively inhibits both the digestive gut and hepatopancreatic fractions, while l-Tryptophan inhibits the hepatopancreatic fraction only.5.5. l-Cysteine and glutathione (reduced) activate the acid phosphatase, while l-phenylalanine, d-phenylalanine, dl-phenylalanine, d-tyrosine, dl-tyrosine, d-tryptophan, dl-tryptophan and l-alanine have no effect. Parachloromercuribenzoate, “β-mercaptoethanol”, iodoacetic acid and l-cystine inhibit the enzyme to varying degrees.6.6. Hydrolysis of phenyl phosphate by the enzyme was inhibited to varying degrees in the presence of heavy metal salts. Inhibition by cadmium nitrate and nickel chrloride was of the order of 40·7 and 12·9 per cent, respectively, while in the case of lead nitrate, silver nitrate and ferric sulphate it was 55·0, 75·6 and 85·2 per cent, respectively.