Premium
Mg 2+ activation of Escherichia coli inorganic pyrophosphatase
Author(s) -
Avaeva Svetlana M.,
Rodina Elena V.,
Kurilova Svetlana A.,
Nazarova Tatjana I.,
Vorobyeva Natalja N.,
Harutyunyan Emil H.,
Oganessyan Vaheh Yu.
Publication year - 1995
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(95)01310-5
Subject(s) - inorganic pyrophosphatase , escherichia coli , pyrophosphatase , chemistry , enzyme , pyrophosphatases , binding site , active site , stereochemistry , crystallography , biochemistry , pyrophosphate , gene
Further refinement of X‐ray data on Escherichia coli inorganic pyrophosphatase [Oganessyan et al. (1994) FEBS Lett. 348, 301–304] to 2.2 Å reveals a system of noncovalent interactions involving Tyr 55 and Tyr 141 in the active site. The pK a for one of the eight Tyr residues in wild‐type pyrophosphatase is as low as 9.1 and further decreases to 8.1 upon Mg 2+ binding, generating characteristic changes in the absorption spectrum. These effects are lost in a Y55F but not in a Y141F variant. It is suggested that the lower‐affinity site for Mg 2+ in the enzyme is formed by Tyr 55 and Asp 70 , which are in close proximity in the apo‐enzyme structure.