Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1179608 | Biochimica et Biophysica Acta (BBA) - Proteins and Proteomics | 2006 | 7 Pages |
Abstract
Hydantoin racemase enzyme together with a stereoselective hydantoinase and a stereospecific d-carbamoylase guarantee the total conversion from d,l-5-monosubstituted hydantoins with a low velocity of racemization, to optically pure d-amino acids. Hydantoin racemase from Sinorhizobium meliloti was expressed in Escherichia coli. Calorimetric and fluorescence experiments were then carried out to obtain the thermodynamic binding parameters, ÎG, ÎH and ÎS for the inhibitors l- and d-5-methylthioethyl-hydantoin. The number of active sites is four per enzyme molecule (one per monomer), and the binding of the inhibitor is entropically and enthalpically favoured under the experimental conditions studied. In order to obtain information about amino acids involved in the active site, four different mutants were developed in which cysteines 76 and 181 were mutated to Alanine and Serine. Their behaviour shows that these cysteines are essential for enzyme activity, but only cysteine 76 affects the binding to these inhibitors.
Keywords
Related Topics
Physical Sciences and Engineering
Chemistry
Analytical Chemistry
Authors
Montserrat Andújar-Sánchez, Sergio MartÃnez-RodrÃguez, Francisco Javier Las Heras-Vázquez, Josefa MarÃa Clemente-Jiménez, Felipe RodrÃguez-Vico, Vicente Jara-Pérez,