NAD(P)H:menadione oxidoreductase of the amitochondriate eukaryote Giardia lamblia: a simpler homologue of the vertebrate enzyme The GenBank accession number for the glQR1-encoding sequence reported in this paper is AF321405

Autor:	Theodore E. Nash, Miklós Müller, Lidya B. Sánchez, Heidi G. Elmendorf
Rok vydání:	2001
Předmět:	chemistry.chemical_classification Protein family Stereochemistry Biology NAD(P)H Dehydrogenase (Quinone) Microbiology Amino acid chemistry.chemical_compound Enzyme chemistry Biochemistry Menadione Oxidoreductase NAD+ kinase Peptide sequence
Zdroj:	Microbiology. 147:561-570
ISSN:	1465-2080 1350-0872
DOI:	10.1099/00221287-147-3-561
Popis:	The amitochondriate eukaryote Giardia lamblia contains an NAD(P)H:menadione oxidoreductase (EC 1.6.99.2) (glQR) that catalyses the two-electron transfer oxidation of NAD(P)H with a quinone as acceptor. The gene encoding this protein in G. lamblia was expressed in Escherichia coli. The purified recombinant protein had an NAD(P)H oxidoreductase activity, with NADPH being a more efficient electron donor than NADH. Menadione, naphthoquinone and several artificial electron acceptors served as substrate for the enzyme. glQR shows high amino acid similarity to its homologues in vertebrates and also to a series of hypothetical proteins from bacteria. Although glQR is considerably smaller than the mammalian enzymes, three-dimensional modelling shows similar arrangement of the secondary structural elements. Most amino acid residues of the mammalian enzymes that participate in substrate binding or catalysis are conserved. Conservation of these features and the similarity in substrate specificity and in susceptibility to inhibitors establish glQR as an authentic member of this protein family.
Databáze:	OpenAIRE
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