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  • Title: Glycerolipid biosynthesis in rat adipose tissue. 11. Effects of polyamines on Mg2+-dependent phosphatidate phosphohydrolase.
    Author: Jamdar SC, Osborne LJ.
    Journal: Biochim Biophys Acta; 1983 Jun 16; 752(1):79-88. PubMed ID: 6303437.
    Abstract:
    The effect of polyamines (spermine, spermidine and putrescine) on the Mg2+-dependent phosphatidate phosphohydrolase was investigated. Phosphatidate phosphohydrolase activity was measured in the presence of aqueous dispersed phosphatidate as substrate, and the release of inorganic phosphate was taken as a measure of phosphatidate phosphohydrolase activity. In the presence of various polyamines there was activation of the Mg2+-dependent phosphatidate phosphohydrolase activity. Under this condition, the Km of enzyme towards phosphatidase decreased from 1.6 x 10(-4) to 9.8 x 10(-5) M and the Mg2+ requirement decreased from 5 to 0.5 mM. These polyvalent cations did not replace Mg2+, but potentiate the phosphohydrolase activity in the presence of Mg2+. The activation of Mg2+-dependent phosphatidate phosphohydrolase activity by polyamines was observed in the presence of 3-sn-phosphatidylcholine, suggesting that these modulators of phosphatidate phosphohydrolase activity may be acting through different mechanisms. These studies demonstrate that polyamines may be important regulators of Mg2+-dependent phosphatidate phosphohydrolase activity in adipose tissue.
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