Acid phosphatases from liver of Rana esculenta. Subcellular localization and partial characterization of multiple forms

Immunolocalization of an acid phosphatase from pearl oyster (Pinctada fucata) and its in vitro effects on calcium carbonate crystal formation

Distribution of an acid phosphatase, AcPase I, from pearl oyster (Pinctada fucata) in different tissues was investigated via enzyme activity determination and immunohistochemistry. Positive reactions were observed in sections of digestive gland, base of gill filaments, and epithelia of the outer side of the middle fold and the inner side of the outer fold, which indicated AcPase I might participate in processes besides immune defense, such as calcium metabolism or shell formation. Its effects on CaCO(3) crystal formation were studied in vitro. Results revealed that AcPase I inhibited CaCO(3) precipitation in a dose-dependent manner and had no affinity for calcium. CaCO(3) crystals induced by AcPase I exhibited a cluster needle-like morphology, which proved to be aragonite. The morphology and size of the aragonites varied with different concentrations of AcPase I. Our observations described here may provide important clues to further understanding of the correlations between mineralization and immune defense in the oyster.

Purification and partial characterization of two acid phosphatase forms from pearl oyster (Pinctada fucata)

The present study describes the details about the acid phosphatase forms in the pearl oyster, Pinctada fucata. Two isoenzymes (AcPase I and II) of acid phosphatase were separated and purified from viscera of pearl oyster, P. fucata to homogeneity by chromatography on DEAE-Sepharose Fast Flow, Sephadex G-200 superfine and ConA Sepharose 4B, and partial biochemical properties of AcPase I and II were studied. AcPase I and AcPase II had molecular weights of 208.8 and 64.3 kDa, respectively. AcPase I was a single polypeptide chain, while AcPase II was a dimeric enzyme composed of two equivalent subunits. AcPase I and II showed optimal pHs at 4.6 and 3.2 with p-nitrophenylphosphate as substrate. The optimal catalytic reaction temperature was 47 degrees C for AcPase I and 57 degrees C for AcPase II. Both enzyme forms were stable when incubated at 50 degrees C for 40 min. Tartrate and fluoride were the most effective inhibitors of the enzymes. Fe(3+), Zn(2+), Cu(2+) and Pb(2+) inhibited the activity of AcPase I and II to differing extents. AcPase I and II were apparently nonspecific and hydrolyzed various phosphoric esters. The different properties of AcPase I and II suggested that the two enzymes may play different roles in the pearl oyster.

Hymenolepis diminuta: further characterization of the membrane-bound acid phosphatase activity associated with the brush border membrane of the tapeworm's tegument

The acid phosphate activity (APA) associated with the isolated brush border membrane of the tapeworm, Hymenolepis diminuta, hydrolyzed p-nitrophenyl phosphate (PNPP), pyrophosphate (PPi), and beta-glycerophosphate (beta GP). Inhibition of PNPP hydrolysis at pH 4.0 was inhibited in a competitive manner by the following compounds (listed in order of decreasing affinity with their apparent inhibitor constants (Ki')): molybdate (0.031 mM); PPi (0.147 mM); NaF (0.150 mM); o-carboxyphenyl phosphate (0.261 mM); inorganic phosphate (0.770)); arsenate (3.45 mM); tartrate (22.1 mM); and beta GP (29.8 mM). Cu2+, formaldehyde, and arsenite at 10:1, 80:1, and 200:1 inhibitor to substrate ratios did not inhibit APA. The maximal rate of hydrolysis (Vmax) of each substrate was greater at pH 4.0 than 5.0. The apparent Michaelis constant (Km') for PNPP increased from 0.233 to 0.351 mM when the pH was raised from 4.0 to 5.0. The Km' for PPi decreased from 0.101 to 0.046 mM, while the Km' for beta GP changed from 2.04 to 2.22 mM under similar circumstances. APA and alkaline phosphatase activity increased as a function of temperature up to 45 degrees C.