title: Different catalytic properties of two highly homologous triosephosphate isomerase monomers.
abstract: It is assumed that amino acid sequence differences in highly homologous enzymes would be found at the peripheral level, subtle changes that would not necessarily affect catalysis. Here, we demonstrate that, using the same set of mutations at the level of the interface loop 3, the activity of a triosephosphate isomerase monomeric enzyme is ten times higher than that of a homologous enzyme with 74% identity and 86% similarity, whereas the activity of the native, dimeric enzymes is essentially the same. This is an example of how the dimeric biological unit evolved to compensate for the intrinsic differences found at the monomeric species level. Biophysical techniques of size exclusion chromatography, dynamic light scattering, X-ray crystallography, fluorescence and circular dichroism, as well as denaturation/renaturation assays with guanidinium hydrochloride and ANS binding, allowed us to fully characterize the properties of the new monomer.
authors.affiliation: Instituto de Química, Departamento de Bioquímica, Universidad Nacional Autónoma de Mexico, Circuito Exterior, Mexico, DF 04510, Mexico.
authors.forename: Francisco
authors.initials: F
authors.lastname: Zárate-Pérez
authors.forename: María Elena
authors.initials: ME
authors.lastname: Chánez-Cárdenas
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Arreola
authors.forename: Alfredo
authors.initials: A
authors.lastname: Torres-Larios
authors.forename: Edgar
authors.initials: E
authors.lastname: Vázquez-Contreras
mesh_terms: D000595:Amino Acid Sequence / Q000235:genetics; D000818:Animals; D002384:Catalysis; D018360:Crystallography, X-Ray; D004795:Enzyme Stability / Q000235:genetics; D019791:Guanidine / Q000737:chemistry; D008027:Light; D009154:Mutation; D011487:Protein Conformation; D011489:Protein Denaturation; D012542:Scattering, Radiation; D014305:Triose-Phosphate Isomerase / Q000737:chemistry* / Q000235:genetics; D014349:Trypanosoma cruzi / Q000201:enzymology
chemical_list: D014305:Triose-Phosphate Isomerase; D019791:Guanidine