LINGCOD MUSCLE PHOSPHOMONOESTERASES: I. ACID PHOSPHATASES THAT HYDROLYZEp-NITROPHENYL PHOSPHATE

Abstract

Five fractions (A to E), each possessing acid phosphomonoesterase activity, were separated from an aqueous extract of the muscle of lingcod (Ophiodon elongatus) by stepwise chromatography on diethylaminoethyl cellulose in the free-base form.Fraction A required Zn⁺⁺or Mn⁺⁺for activity, was inhibited by heparin, and had its pH optimum at 6.0. Fraction E required Zn⁺⁺for activity, was not inhibited by heparin, and had its pH optimum at 5.5. Fractions B, C, and D did not require metal ions for activity, and were distinguished from each other by differences in response to pH, cysteine, ethylenediaminetetraacetate, fluoride, and tartrate.The pH range over which fraction A was active was shifted to slightly higher values when Mn⁺⁺was the activator rather than Zn⁺⁺. Also, A was inhibited strongly by cysteine when activated by Zn⁺⁺, but not when activated by Mn⁺⁺. Data are presented that indicate these differences were due to different properties of the activating ions, rather than to the presence in fraction A of two enzymes, one activated by Zn⁺⁺and the other by Mn⁺⁺.