Repository logo

Browsing by Author "Oliveira, M. P."

Now showing 1 - 2 of 2
  • A novel method for determination of inorganic polyphosphates using the fluorescent dye fura-2
    Publication . Lorenz, B.; Munkner, J.; Oliveira, M. P.; Leitão, José; Muller, W. E. G.; Schroder, H. C.
    A method for determining inorganic polyphosphate, which is based on the Mn2+-induced quenching of the fluorescence of the calcium indicator fura-2, is described. The effect of Mn2+ ions on fura-2 fluorescence is gradually abolished in the presence of increasing concentrations of polyphosphate; this allows the quantification both of synthetic polyphosphates and of the naturally occurring polymer isolated from tissues or cells. The described method has some advantages compared to conventional procedures for detection of polyphosphates based on the metachromatic effect on toluidine blue. It can be applied for the determination of pyrophosphate, tripolyphosphate and other short-chain polyphosphates not detectable by toluidine blue and it can be used for measurement both of pyrophosphatase and exopolyphosphatase activity. (C) 1997 Academic Press.
    1997Journal article Restricted Show more
  • Changes in metabolism of inorganic polyphosphate in rat tissues and human cells during development and apoptosis
    Publication . Lorenz, B.; Munkner, J.; Oliveira, M. P.; Kuusksalu, A.; Leitão, J. M.; Muller, W. E. G.; Schroder, H. C.
    Age-dependent studies show that the amount of inorganic polyphosphate in rat brain strongly increases after birth. Maximal levels were found in 12-months old animals. Thereafter, the concentration of total polyphosphate decreases to about 50%. This decrease in the concentration of total polyphosphate is due to a decrease in the amount of insoluble, long-chain polyphosphates. The amount of soluble, long-chain polyphosphates does not change significantly in the course of ageing. In rat embryos and newborns, mainly soluble polyphosphates could be detected. In rat liver, the age-dependent changes are less pronounced. The changes in polyphosphate level are accompanied by changes in exopolyphosphatase activity, which degrades the polymers to orthophosphate; highest enzyme activities were found when the polyphosphate level was low, Induction of apoptosis in the human leukemic cell line HL-60 by actinomycin D results in degradation of long polyphosphate chains. The total polyphosphate content does not change significantly in apoptotic cells.
    1997Journal article Restricted Show more