title: Purification and characterization of Taenia crassiceps cysticerci thioredoxin: insight into thioredoxin-glutathione-reductase (TGR) substrate recognition.
abstract: Thioredoxin (Trx) is an oxidoreductase central to redox homeostasis in cells and is involved in the regulation of protein activity through thiol/disulfide exchanges. Based on these facts, our goal was to purify and characterize cytosolic thioredoxin from Taenia crassiceps cysticerci, as well as to study its behavior as a substrate of thioredoxin-glutathione reductase (TGR). The enzyme was purified >133-fold with a total yield of 9.7%. A molecular mass of 11.7kDa and a pI of 4.84 were measured. Native electrophoresis was used to identify the oxidized and reduced forms of the monomer as well as the presence of a homodimer. In addition to the catalytic site cysteines, cysticerci thioredoxin contains Cys28 and Cys65 residues conserved in previously sequenced cestode thioredoxins. The following kinetic parameters were obtained for the substrate of TGR: a Km of 3.1μM, a kcat of 10s(-1) and a catalytic efficiency of 3.2×10(6)M(-1)s(-1). The negative patch around the α3-helix of Trx is involved in the interaction with TGR and suggests variable specificity and catalytic efficiency of the reductase toward thioredoxins of different origins.
authors.affiliation: Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México (UNAM), Apartado Postal 70-159, 04510 México, D.F., México.
authors.forename: J J
authors.initials: JJ
authors.lastname: Martínez-González
authors.affiliation: Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México (UNAM), Apartado Postal 70-159, 04510 México, D.F., México.
authors.forename: A
authors.initials: A
authors.lastname: Guevara-Flores
authors.affiliation: Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México (UNAM), Apartado Postal 70-159, 04510 México, D.F., México.
authors.forename: J L
authors.initials: JL
authors.lastname: Rendón
authors.affiliation: Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México (UNAM), Apartado Postal 70-159, 04510 México, D.F., México.
authors.forename: A
authors.initials: A
authors.lastname: Sosa-Peinado
authors.affiliation: Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México (UNAM), Apartado Postal 70-159, 04510 México, D.F., México.
authors.forename: I P
authors.initials: IP
authors.lastname: Del Arenal Mena
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D005260:Female; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000235:genetics / Q000378:metabolism*; D009247:NADH, NADPH Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D011487:Protein Conformation; D013379:Substrate Specificity; D013621:Taenia / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D013879:Thioredoxins / Q000235:genetics / Q000378:metabolism*
chemical_list: D009097:Multienzyme Complexes; D013879:Thioredoxins; D009247:NADH, NADPH Oxidoreductases; C466433:thioredoxin glutathione reductase
keywords: Taenia crassiceps; Taenia solium; platyhelminths; thioredoxin; thioredoxin-glutathione reductase