ISSN:
1550-7408
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Biology
Notes:
SYNOPSIS. Properties and cellular location of acid phosphatase in Trypanosoma gambiense were studied. Activity was found in both the sediment (32,000 ×g) and the supernatant of homogenates. Cenrifugation in 0.3 M sucrose showed activity principally in the lowspeed fraction (4,000 ×g). One min of sonication released most of this activity. Several phosphomonoesters were hydrolyzed at acid H's. Enzymatic activity was relatively specific for pyrophosphate and p-nitrophenylphosphate at pH 3.6. At pH 5.2, purine and pyimidine nucleotide 5′-triphosphates as well as adenosine di- and ono-5′-phosphates were hydrolyzed nonspecifically. Activity with yrophosphate at pH 3.6 had a temperature optimum of 60-70 C while that for adenosine 5′-triphosphate (pH 5.2) was 50 C. These ctivities of the sediment required no metal co-factors and were inibited by Fe++, inhibition at the lower pH being greater.Glucose 6-phosphate was hydrolyzed by the supernatant with maximum activity between pH 6.0 and 7.2 and a temperature optimum of 50 C. This pH range showed a broad plateau with 2 or 3 minor peaks. The hydrolysis of p-nitrophenylphosphate showed a similar pH curve. In glucose 6-phosphate hydrolysis, Mg++ was a required co-factor but could be replaced by Ni++ or Co++. Ammonium sulfate fractionation precipitated most of the supernatant activity between 50 and 75% saturation.A modified Gomori technic produced spherical deposits of PbS thruout the cytoplasm of the intact cell. With the electron microscope, Pb phosphate deposition was observed in membrane-bound vesicles (i.e., lysosomes) approximately 100-150 mμ in diameter. These organelles were common in the region of the reservoir at the base of the flagellum. Acid phosphatase activity specific for glucose 6-phosphate as substrate was localized within this basal pocket.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1550-7408.1967.tb01457.x
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