Disruption of Escherichia coli transaldolase into catalytically active monomers: evidence against half‐of‐the‐sites mechanism

FEBS Letters

Schörken, Ulrich²  Sahm, Hermann²  Schneider, Gunter¹  Sprenger, Georg A.²  Jia, Jia¹ 

[1] Division of Molecular Structural Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Doktorsringen 9, S-171 77 Stockholm, Sweden;Institut für Biotechnologie 1, Forschungszentrum Jülich GmbH, P.O. Box 1913, D-52425 Jülich, Germany

关键词: Class I aldolase;    Transaldolase;    Site-directed mutagenesis;    Protein crystallography;    Half-of-the-sites mechanism;   

DOI  :  10.1016/S0014-5793(98)01521-X

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

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.

【 授权许可】

Unknown