| 17113080 |
de Sa Pinheiro AA, Amazonas JN, de Souza Barros F, De Menezes LF, Batista EJ, Silva EF, De Souza W, Meyer-Fernandes JR: Entamoeba histolytica: an ecto-phosphatase activity regulated by oxidation-reduction reactions. Exp Parasitol. 2007 Apr;115(4):352-8. Epub 2006 Nov 17.
In this work, an ecto-phosphatase activity of Entamoeba histolytica was characterized using intact cells. This activity presented the following biochemical characteristics: (i) it hydrolyzes p-NPP with V (max) of 8.00+/-0.22 nmol p-NP x h (-1) x 10 (-5) cells and K (m) of 2.68+/-0.25 mM; (ii) it is inhibited by acid phosphatase inhibitors, such as sodium molybdate (K (i)=1.70+/-0.24 microM) and sodium fluoride (K (i)=0.25+/-0.02 mM); (iii) it also showed high sensitivity to phosphotyrosine phosphatase inhibitors, such as sodium orthovanadate (K (i)=1.07+/-0.14 microM), bpV-PHEN (K (i)=0.38+/-0.02 microM) and mpV-PIC (K (i)=0.39+/-0.04 microM). Zn (2+), an oxidizing agent, decreased the enzymatic activity in 50%. DTT and GSH, two reducing agents, enhanced the activity twofold. The non-invasive E. histolytica and free-living E. moshkovskii were less efficient in hydrolyzing p-NPP than the pathogenic E. histolytica suggesting that this enzyme could represent a virulence marker for this cell. |
31(0,1,1,1) |