Identity of zinc ion-dependent acid phosphatase from bovine brain and myo-inositol 1-phosphatase

Abstract

A 62 kDa Zn2+-dependent acid phosphatase has been purified from bovine brain. The protein was carboxymethylated and then cleaved by endoproteinase GIu-C, trypsin and CNBr. Several fragments were subjected to structural analysis either by using mass spectrometry or automated peptide sequencing. The four sequenced peptides were compared with the known protein sequences contained in the EMBL Data Bank. All four peptide sequences were identical to the corresponding amino-acid sequences present in myo-inositol 1-phosphatase from bovine brain. Furthermore we found that the amino-acid composition of Zn2+-dependent acid phosphatase purified in our laboratory is very similar to that of myo-inositol 1-phosphatase, and that several peptide fragments have molecular weights (measured by mass spectrometry techniques) identical to those expected for cleavage-fragments originated from the authentic myo-inositol l-phosphatase. This is one of the key enzymes in the receptor-stimulated inositol phospholipid metabolism and it has been considered as the probable target of Li ÷ ion during LiC1 therapy in manic-depressive patients. The comparison of the Zn2+-dependent acid phosphatase and the Mg 2 +-dependent myo-inositol-1-phosphatase activities, measured at different purification steps, shows that the ratio between the two activities was remarkably constant during enzyme purification. We also demonstrated that in the presence of Mg 2+ this enzyme efficiently catalyses the hydrolysis of myo-inositol l-phosphate, and that the Li + ion inhibits this activity. Furthermore, the thermal treatment of the enzyme causes a time-dependent parallel decrease of both Zn-dependent p-nitrophenyl phosphatase (assayed at pH 5.5) and Mg2+-dependent myo-inositol-l-phosphatase (assayed at pH 8.0) activities, suggesting the hypothesis that the same protein possesses both these activities.

Occurrence of myo-inositol-1-phosphate phosphatase in pteridophytes: characteristics of the enzyme from the reproductive pinnules of Dryopteris filix-mas (L.) Schott

“…Chhetri et al (2005Chhetri et al ( , 2006 have already established the occurrence of the prime enzyme of myo-inositol biosynthesis, MIPS, in pteridophytes. Therefore, the presence of MIPP adds (Eisenberg Jr. 1967, Attwood et al, 1988Gee et al, 1988;Honchar et al, 1989;Leech et al, 1993;Pollack et al, 1994;Caselli et al, 1996, Fujimoto et al, 1996, Nigou and Besra, 2002Wang et al, 2006;Patra et al, 2007). However, its kinetic parameter, thermo-tolerance and calciumdependent inhibition at lower concentrations, differ substantially in pteridophytic species.…”

“…In pteridophytes, Benaroya et al (2004) and Chettri et al (2005Chettri et al ( , 2006 have recently documented the occurrence and characterization of L-myo-inositol-1-phosphate synthase. So far, work with regard to the participation of the subsequent enzyme in this metabolic sequence, myo-inositol-1-phosphate phosphatase (MIPP), has been carried out principally in animal systems (Eisenberg Jr, 1967;Attwood et al, 1988;Gee et al, 1988;Honchar et al, 1989;Leech et al, 1993;Pollack et al, 1994;Kwok and Lo, 1994;Fujimoto et al, 1996;Caselli et al, 1996), in archaea (Wang et al, 2006), in bacteria (Nigou and Besra, 2002), and in cyanobacteria (Patra et al, 2007). However, only a few reports are available of this enzyme from plant systems (Loewus and Loewus, 1983;Gumber et al, 1984).…”

Acid phosphatases of Esox lucius: tissue distribution and partial characterization

“…These enzymes seem to be cytosolic and show a restricted tissue expression (Panara et al, 1992;Fujimoto et al, 1993). The activity of LMW-ZnAP as myo-inositol-1-phosphatase in bovine brain was described recently (Fujimoto et al, 1996;Caselli et al, 1996). This is one of the key enzymes in the receptor-stimulated phospholipid metabolism in mammalian brain and may be involved in cell signalling systems mediated by phosphoinositides (Fujimoto et al, 1996).…”