Relevance of phenylalanine 216 in the affinity of <Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis> phosphoenolpyruvate carboxykinase for Mn(II) |
| |
Authors: | Alejandro Yévenes Fernando D González-Nilo Emilio Cardemil |
| |
Institution: | (1) Departamento de Ciencias Químicas, Facultad de Química y Biología, Universidad de Santiago de Chile, Casilla 40, Santiago 33, Chile;(2) Present address: Centro de Bioinformática y Simulación Molecular, Universidad de Talca, Talca, Chile |
| |
Abstract: | Saccharomyces cerevisiae phosphoenolpyruvate (PEP) carboxykinase catalyzes the reversible formation of oxaloacetate and adenosine triphosphate from
PEP, adenosine diphosphate and carbon dioxide, and uses Mn2+ as the activating metal ion. Comparison with the crystalline structure of homologous Escherichia coli PEP carboxykinase Tari et al. (1997) Nature Struct. Biol.
4, 990–994] shows that Lys213 is one of the ligands to Mn2+ at the enzyme active site. Coordination of Mn2+ to a lysyl residue is not common and suggests a low pK
a value for the ε-NH2 group of Lys213. In this work, we evaluate the role of neighboring Phe216 in contributing to provide a low polarity microenvironment suitable to keep the ε-NH2 of Lys213 in the unprotonated form. Mutation Phe216Tyr shows that the introduction of a hydroxyl group in the lateral chain of the
residue produces a substantial loss in the enzyme affinity for Mn2+, suggesting an increase of the pK
a of Lys213. In agreement with this interpretation, theoretical calculations indicate an alkaline shift of 2.8 pH units in the pK
a of the ε-amino group of Lys213 upon Phe216Tyr mutation. |
| |
Keywords: | Phosphoenolpyruvate carboxykinase manganese binding site Saccharomyces cerevisiae theoretical pK a calculations manganese ligands in protein |
本文献已被 PubMed SpringerLink 等数据库收录! |
|