Neurochemical Research

, Volume 30, Issue 5, pp 641–649

Purification of an Endogenous Inhibitor of L-Dopa Decarboxylase Activity from Human Serum

  • Alice-Georgia Vassiliou
  • Dido Vassilacopoulou
  • Emmanuel G. Fragoulis
Article

DOI: 10.1007/s11064-005-2752-7

Cite this article as:
Vassiliou, AG., Vassilacopoulou, D. & Fragoulis, E.G. Neurochem Res (2005) 30: 641. doi:10.1007/s11064-005-2752-7

Abstract

An endogenous inhibitor of l-Dopa decarboxylase was identified and purified from human serum. In Triton X-114 partitioning experiments, the inhibitor was recovered in the detergent enriched phase, suggesting a hydrophobic nature. Purification was achieved by means of proteinase K digestion, ammonium sulphate precipitation, phenyl sepharose hydrophobic chromatography and subsequent extraction from a nondenaturing polyacrylamide gel. This purification scheme resulted in the isolation of a single 25 kDa band, bearing l-Dopa decarboxylase inhibitory activity. The purified molecule was found to be resistant to heat and digestion by various proteases. Proteolytic digestion of the purified inhibitor by pronase and aminopeptidase M was achieved only following carboxymethylation. The biological importance of the presence of an l-Dopa decarboxylase activity inhibitor in normal biological fluids remains to be elucidated. The better understanding of the regulation of Ddc enzymatic activity could prove valuable in the clarification of the enzyme’s role in a series of pathological conditions, as well as, in physiological regulatory mechanisms.

Key words:

Carboxymethylationendogenous inhibitorL-Dopa decarboxylaseserumproteinase KTriton X-114

Copyright information

© Springer Science+Business Media, Inc. 2005

Authors and Affiliations

  • Alice-Georgia Vassiliou
    • 1
  • Dido Vassilacopoulou
    • 1
  • Emmanuel G. Fragoulis
    • 1
    • 2
  1. 1.Dept. of Biochemistry and Molecular BiologyUniversity of AthensZografouGreece
  2. 2.University of Athens, Department of Biochemistry and Molecular BiologyUniversity of AthensZografouGreece