Control of the reactivation kinetics of homodimeric triosephosphate isomerase from unfolded monomers

Zomosa Signoret V

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Título :	Control of the reactivation kinetics of homodimeric triosephosphate isomerase from unfolded monomers
Creador:	Zomosa Signoret V
Nivel de acceso:	Open access
Palabras clave :	Triosa-Fosfato Isomerasa - química Triosa-Fosfato Isomerasa - metabolismo Trypanosoma brucei brucei - enzimología Trypanosoma cruzi - Enzimpología Triose-Phosphate Isomerase - chemistry Triose-Phosphate Isomerase - metabolism Trypanosoma brucei brucei - enzymology Trypanosoma cruzi - enzymology Amino acids; Biological membranes; Catalysis; Dimers; Reaction kinetics; Dimer formation; Enzymes; guanidine; monomer; triosephosphate isomerase; amino acid sequence; article; catalysis; dimerization; enzyme activation; enzyme activity; enzyme analysis; enzyme denaturation; enzyme inactivation; enzyme kinetics; enzyme stability; enzyme structure; priority journal; protein folding; reaction analysis; Trypanosoma brucei; Trypanosoma cruzi; Animals; Base Sequence; Circular Dichroism; Dimerization; DNA Primers; Enzyme Activation; Kinetics; Mutagenesis; Protein Denaturation; Recombinant Proteins; Spectrometry, Fluorescence; Triose-Phosphate Isomerase; Trypanosoma brucei brucei; Trypanosoma cruzi; Protozoa; Trypanosoma; Trypanosoma brucei; Trypanosoma cruzi
Descripción :	Homodimeric triosephosphate isomerases from Trypanosoma cruzi (TcTIM) and Trypanosoma brucei (TbTIM) have markedly similar catalytic properties and 3-D structures; their overall amino acid sequence identity is 68% and 85% in their interface residues. Nonetheless, active dimer formation from guanidinium chloride unfolded monomers is faster and more efficient in TcTIM than in TbTIM. The enzymes thus provide a unique opportunity for exploring the factors that control the formation of active dimers. The kinetics of reactivation at different protein concentrations showed that the process involved three reactions: monomer folding, association of folded monomers, and a transition from inactive to active dimers. The rate constants of the reactions indicated that, at relatively low protein concentrations, the rate-limiting step of reactivation was the association reaction; at high protein concentrations the transition of inactive to active dimers was rate limiting. The rates of the latter two reactions were higher in TcTIM than in TbTIM. Studies with a mutant of TcTIM that had the interface residues of TbTIM showed that the association rate constant was similar to that of TbTIM. However, the rate of the transition from inactive to active dimers was close to that of TcTIM; thus, this transition depends on the noninterfacial portion of the enzymes. When unfolded monomers of TcTIM and TbTIM were allowed to reactivate together, TcTIM, the hybrid, and TbTIM were formed in a proportion of 1:0.9:0.2. This distribution suggests that, in the hybrid, the characteristics of the TcTIM monomers influence the properties of TbTIM monomers.
Colaborador(es) u otros Autores:	Hernández Alcántara G Reyes Vivas H Martínez Martínez E Garza Ramos G Pérez Montfort R Tuena De Gómez-Puyou M Gómez Puyou A
Fecha de publicación :	2003
Tipo de publicación:	Artículo
Formato:	pdf
Identificador del Recurso :	10.1021/bi0206560
Fuente:	Biochemistry 42(11):3311 - 3318
URI :	http://repositorio.pediatria.gob.mx:8180/handle/20.500.12103/2225
Idioma:	eng
Aparece en las colecciones:	Artículos

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