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Arch Biochem Biophys. 2013 Oct 15;538(2):103-10. doi: 10.1016/j.abb.2013.08.014. Epub 2013 Sep 3.

UDP-galactopyranose mutases from Leishmania species that cause visceral and cutaneous leishmaniasis.

Author information

1
Department of Biochemistry, Virginia Tech, Blacksburg, VA 24061, United States; Fralin Life Science Institute, Virginia Tech, Blacksburg, VA 24061, United States.

Abstract

Leishmaniasis is a vector-borne, neglected tropical disease caused by parasites from the genus Leishmania. Galactofuranose (Galf) is found on the cell surface of Leishmania parasites and is important for virulence. The flavoenzyme that catalyzes the isomerization of UDP-galactopyranose to UDP-Galf, UDP-galactopyranose mutase (UGM), is a validated drug target in protozoan parasites. UGMs from L. mexicana and L. infantum were recombinantly expressed, purified, and characterized. The isolated enzymes contained tightly bound flavin cofactor and were active only in the reduced form. NADPH is the preferred redox partner for both enzymes. A kcat value of 6 ± 0.4s(-1) and a Km value of 252 ± 42 μM were determined for L. infantum UGM. For L. mexicana UGM, these values were ∼4-times lower. Binding of UDP-Galp is enhanced 10-20 fold in the reduced form of the enzymes. Changes in the spectra of the reduced flavin upon interaction with the substrate are consistent with formation of a flavin-iminium ion intermediate.

KEYWORDS:

Flavin-dependent reaction; Galactofuranose; Neglected diseases; Non-redox reaction

PMID:
24012809
PMCID:
PMC3849806
DOI:
10.1016/j.abb.2013.08.014
[Indexed for MEDLINE]
Free PMC Article

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