title: Purification, characterization and kinetic properties of the Taenia solium glutathione S-transferase isoform 26.5 kDa.
abstract: Glutathione S-transferases are major phase II detoxification enzymes. Taenia solium, a parasite of humans and pigs, is exposed to toxic products. The aim of this work was to purify and characterize a T. solium glutathione S-transferase isoform of 26.5 kDa (SGST26.5) in order to obtain its kinetic parameters. Homogeneous SGST26.5 was obtained by a simple purification procedure. SGST26.5 showed a p I of 7.07, and a native Mr of 60 kDa with 26.5 kDa subunits. The optimum activity for SGST26.5 was found at pH 6.5-7.0 in the range 10-42 degrees C. SGST26.5 had a specific enzyme activity of 78, 7.1, 6.6, and 0.7 microM min(-1) mg(-1) with CDNB, 1,2-dichloro-4-nitrobenzene, 2,4-hexadienal and trans-2-nonenal as substrates, respectively. It also had a kcat/ K(mCDNB)=2.15 x 10(3) M(-1 )s(-1), kcat/ KmGSH)=4.5 x 10(3) M(-1 )s(-1) and Vmax for GSH and CDNB=74 and 77 microM min(-1) mg(-1), respectively. SGST26.5 was inhibited in a noncompetitive form by cibacron blue, bromosulfophthalein and triphenyltin chloride. Inhibition studies as a function of inhibitor concentration show that the enzyme is a homodimer. Bireactant system analysis show that it follows an ordered sequential mechanism.
authors.affiliation: Departamento de Microbiología y Parasitología, Facultad de Medicina, Universidad Nacional Autónoma de México, UNAM, Circuiro interior, 04510, Mexico City, Mexico. apc@servidor.unam.mx
authors.forename: A
authors.initials: A
authors.lastname: Plancarte
authors.forename: J L
authors.initials: JL
authors.lastname: Rendon
authors.forename: A
authors.initials: A
authors.lastname: Landa
mesh_terms: D000818:Animals; D005982:Glutathione Transferase / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007527:Isoenzymes / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D007700:Kinetics; D013621:Taenia / Q000201:enzymology* / Q000254:growth & development; D013696:Temperature
chemical_list: D007527:Isoenzymes; D005982:Glutathione Transferase