Disruption of Escherichia coli transaldolase into catalytically active monomers: evidence against half-of-the-sites mechanism.
Disruption of the hydrogen bonding network at the interface of Escherichia coli transaldolase by substitution of R300 to a glutamic acid residue resulted in a monomeric enzyme at basic pH values, with almost no change in the kinetic parameters. The stability of the R300A and R300E mutants towards urea and thermal inactivation is similar to that of the wild-type enzyme. X-ray analysis showed that no structural changes occurred as a consequence of the side chain replacement. This indicates that the quaternary structure is not required for catalytic activity nor does it contribute significantly to the stability of the enzyme. The results are not consistent with a proposed half-of-the-sites reaction mechanism.
Schörken
U
U
Institut für Biotechnologie 1, Forschungszentrum Jülich GmbH, Germany.
Jia
J
J
Sahm
H
H
Sprenger
G A
GA
Schneider
G
G
D019943:Amino Acid Substitution; D001483:Base Sequence; D002384:Catalysis; D003461:Crystallography; D017931:DNA Primers; D004926:Escherichia coli / Q000201:enzymology*; D006860:Hydrogen Bonding; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D016297:Mutagenesis, Site-Directed; D011487:Protein Conformation; D014153:Transaldolase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
D017931:DNA Primers; D014153:Transaldolase