PMID:8543015
| Citation |
Avaeva, SM, Rodina, EV, Kurilova, SA, Nazarova, TI, Vorobyeva, NN, Harutyunyan, EH and Oganessyan VYu, (1995) Mg2+ activation of Escherichia coli inorganic pyrophosphatase. FEBS Lett. 377:44-6 |
|---|---|
| Abstract |
Further refinement of X-ray data on Escherichia coli inorganic pyrophosphatase [Oganessyan et al. (1994) FEBS Lett. 348, 301-304] to 2.2 A reveals a system of noncovalent interactions involving Tyr55 and Tyr141 in the active site. The pKa for one of the eight Tyr residues in wild-type pyrophosphatase is as low as 9.1 and further decreases to 8.1 upon Mg2+ 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 Mg2+ in the enzyme is formed by Tyr55 and Asp70, which are in close proximity in the apo-enzyme structure. |
| Links | |
| Keywords |
Binding Sites; Crystallography, X-Ray; Enzyme Activation/drug effects; Escherichia coli/enzymology; Hydrogen-Ion Concentration; Inorganic Pyrophosphatase; Magnesium/metabolism; Magnesium/pharmacology; Molecular Structure; Pyrophosphatases/chemistry; Pyrophosphatases/metabolism; Recombinant Proteins; Spectrophotometry; Tyrosine/chemistry |
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