@article{3141316,
    title = "Purification and partial characterization of the xanthine-uric acid
transporter (UapA) of Aspergillus nidulans",
    author = "Lemuh, Njimoh Dieudonne and Diallinas, George and Frillingos, Stathis and and Mermelekas, George and Karagouni, Amalia D. and Hatzinikolaou, and Dimitris G.",
    journal = "Protein Expression and Purification",
    year = "2009",
    volume = "63",
    number = "1",
    pages = "33-39",
    publisher = "ACADEMIC PRESS INC ELSEVIER SCIENCE",
    issn = "1046-5928, 1096-0279",
    doi = "10.1016/j.pep.2008.08.012",
    keywords = "Membrane proteins; Purine transport; Aspergillus nidulans;
Overexpression-purification system; Circular dichroism",
    abstract = "UapA, the uric acid-xanthine permease from the filamentous ascomycete
Aspergillus nidulans, is one of the most thoroughly characterized
purine/H+ transporters in eukaryotes. Detailed studies have addressed
its regulation of expression, at both the transcriptional and
post-translational levels, in response to physiological and
developmental signals. An extensive kinetic profile towards a plethora
of purines and mutational analyses have established models on how UapA
recognizes the purine ring and revealed specific amino acid residues
involved in proper folding, topogenesis, function and specificity. The
present work describes for the first time the purification of the UapA
transporter of A. nidulans through overexpression via the strong,
ethanol-inducible, glucose-repressible, alcA promoter. Purification,
almost to homogeneity, was achieved by Ni2+ affinity chromatography
using a functional His-tagged UapA protein version. It is subsequently
shown, by Circular Dichroism (CD) spectroscopy, that the purified
protein is structured with a high alpha-helical content, as expected
from the in silico predictions. The result of this work opens the way
for further, analytical and biochemical Studies on UapA at the protein
level. (c) 2008 Elsevier Inc. All rights reserved."
}