Instituto de Bioquímica Médica, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, UFRJ, Cidade Universitária, Rio de Janeiro, RJ, Brazil.
FEMS Microbiol Lett. 2011 Apr;317(1):34-42. doi: 10.1111/j.1574-6968.2011.02216.x. Epub 2011 Feb 1.
Candida parapsilosis is considered to be an emerging fungal pathogen because it is associated with an increasing range of infections. In this work, we biochemically characterized ecto-5'-nucleotidase activity on the surface of living, intact C. parapsilosis cells. At a pH of 4.5, intact cells were able to hydrolyze 5'-AMP at a rate of 52.44 ± 7.01 nmol Pi h(-1) 10(-7) cells. 5'-AMP, 5'-IMP and 5'-UMP were hydrolyzed at similar rates, whereas 5'-GMP and 5'-CMP hydrolyzed at lower rates. Enzyme activity was increased by about 42% with addition of Mg(2+) or Ca(2+), and the optimum pH was in the acidic range. An inhibitor of phosphatase activities, sodium orthovanadate, showed no effect on AMP hydrolysis; however, as expected, ammonium molybdate, a classical nucleotidase inhibitor, inhibited the activity in a dose-dependent manner. The results indicated that the existence of an ecto-5'-nucleotidase could play a role in the control of extracellular nucleotide concentrations.
近平滑假丝酵母被认为是一种新兴的真菌病原体，因为它与越来越多的感染有关。在这项工作中，我们对活的、完整的近平滑假丝酵母细胞表面的外切 5'-核苷酸酶活性进行了生化特征分析。在 pH 值为 4.5 时，完整的细胞能够以 52.44 ± 7.01 nmol Pi h(-1) 10(-7)细胞的速率水解 5'-AMP。5'-AMP、5'-IMP 和 5'-UMP 的水解速率相似，而 5'-GMP 和 5'-CMP 的水解速率较低。添加 Mg(2+)或 Ca(2+)可使酶活性增加约 42%，最适 pH 值在酸性范围内。磷酸酶活性的抑制剂正钒酸钠对 AMP 水解没有影响；然而，正如预期的那样，钼酸铵，一种经典的核苷酸酶抑制剂，以剂量依赖的方式抑制了该活性。结果表明，外切 5'-核苷酸酶的存在可能在控制细胞外核苷酸浓度方面发挥作用。
