Detection, Purification and Identification of An Endogenous Inhibitor of l-Dopa Decarboxylase Activity from Human Placenta
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An endogenous inhibitor of l-Dopa decarboxylase activity was identified and purified from human placenta. The endogenous inhibitor of l-Dopa decarboxylase (Ddc) was localized in the membrane fraction of placental tissue. Treatment of membranes with phosphatidylinositol-specific phospholipase C or proteinase K did not affect membrane-associated Ddc inhibitory activity, suggesting that a population of the inhibitor is embedded within membranes. Purification was achieved by extraction from a nondenaturing polyacrylamide gel. The purification scheme resulted in the isolation of a single 35 kDa band, bearing l-Dopa decarboxylase inhibitory activity. The purified inhibitor was identified as Annexin V. The elucidation of the biological importance of the presence of an l-Dopa decarboxylase activity inhibitor in normal human tissues could provide us with new information leading to the better understanding of the biological pathways that Ddc is involved in.
KeywordsDdc Membrane Activity inhibitor Annexin V Placenta
This work was partially supported by a Faculty Research Grant from the Empeirikeio Foundation, Greece and represents part of the Doctoral thesis of Miss A.G. Vassiliou.
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