Publication Abstract from PubMed
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.
Mg2+ activation of Escherichia coli inorganic pyrophosphatase.,Avaeva SM, Rodina EV, Kurilova SA, Nazarova TI, Vorobyeva NN, Harutyunyan EH, Oganessyan VYu FEBS Lett. 1995 Dec 11;377(1):44-6. PMID:8543015[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
