Henz Sandra Liana, Ribeiro Cristiane Guimarães, Rosa Aline, Chiarelli Rafael Augusto, Casali Emerson André, Sarkis João José Freitas
Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Avenida Ramiro Barcelos 2600-Anexo, 90035-003, Porto Alegre, RS, Brazil.
Cell Biol Int. 2006 Mar;30(3):214-20. doi: 10.1016/j.cellbi.2005.10.027. Epub 2006 Feb 9.
The participation of ecto-ATP diphosphohydrolase (CD39; ecto-NTPDase) and ecto-5'-nucleotidase (CD73) activities in the nucleotide hydrolysis by salivary gland cells from rats was evaluated. We investigated the biochemical characteristics of these ectoenzymes in cells cultured from submandibular salivary glands of rats. The V(max) for the hydrolysis of ATP, ADP and AMP were 2275+/-153 (mean+/-SEM, n = 4), 941+/-96 (mean+/-SEM, n = 5) and 175+/-5 (mean+/-SEM, n = 5) nmol Pi liberated per min per mg of protein, respectively. The K(m) values for ATP, ADP and AMP were 224+/-8 microM (mean+/-SEM, n = 4), 163+/-15 microM (mean+/-SEM, n = 5) and 117+/-5 microM (mean+/-SEM, n = 5), respectively. The competition plot showed that ATP and ADP were hydrolyzed at the same active site on the enzyme. It may be postulated that the physiological role for this ecto-enzyme cascade is to terminate the action of the co-transmitter ATP, generating adenosine.
评估了胞外ATP二磷酸水解酶（CD39；胞外NTPDase）和胞外5'-核苷酸酶（CD73）活性在大鼠唾液腺细胞核苷酸水解中的作用。我们研究了从大鼠下颌下唾液腺培养的细胞中这些胞外酶的生化特性。ATP、ADP和AMP水解的V(max)分别为每分钟每毫克蛋白质释放2275±153（平均值±标准误，n = 4）、941±96（平均值±标准误，n = 5）和175±5（平均值±标准误，n = 5）nmol无机磷。ATP、ADP和AMP的K(m)值分别为224±8 μM（平均值±标准误，n = 4）、163±15 μM（平均值±标准误，n = 5）和117±5 μM（平均值±标准误，n = 5）。竞争图显示ATP和ADP在酶的同一活性位点被水解。可以推测，这种胞外酶级联反应的生理作用是终止共递质ATP的作用，生成腺苷。
