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Inorganic pyrophosphatases: One substrate, three mechanisms
Author(s) -
Kajander Tommi,
Kellosalo Juho,
Goldman Adrian
Publication year - 2013
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/j.febslet.2013.05.003
Subject(s) - pyrophosphatases , pyrophosphate , thermotoga maritima , membrane , hydrolysis , chemistry , substrate (aquarium) , biochemistry , biophysics , enzyme , biology , escherichia coli , ecology , gene
Soluble inorganic pyrophosphatases (PPases) catalyse an essential reaction, the hydrolysis of pyrophosphate to inorganic phosphate. In addition, an evolutionarily ancient family of membrane‐integral pyrophosphatases couple this hydrolysis to Na + and/or H + pumping, and so recycle some of the free energy from the pyrophosphate. The structures of the H + ‐pumping mung bean PPase and the Na + ‐pumping Thermotoga maritima PPase solved last year revealed an entirely novel membrane protein containing 16 transmembrane helices. The hydrolytic centre, well above the membrane, is linked by a charged “coupling funnel” to the ionic gate about 20 Å away. By comparing the active sites, fluoride inhibition data and the various models for ion transport, we conclude that membrane‐integral PPases probably use binding of pyrophosphate to drive pumping.