2Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119991 Moscow, Russia; E-mail: email@example.com
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Received April 18, 2017; Revision received April 25, 2017
Pyrophosphate regulates vital cellular reactions, and its level in E. coli cells is under the ultimate control of inorganic pyrophosphatase. The mechanisms involved in the regulation of pyrophosphatase activity still need to be elucidated. The present study demonstrated that fructose-1-phosphate inhibits pyrophosphatase activity by a mechanism not involving competition with substrate for binding to the active site. The inhibition constant governing the binding of the inhibitor to the enzyme–substrate complex is 1.1 mM. Substitutions of Lys112, Lys115, Lys148, and Arg43 in the regulatory site completely or partially abolished the inhibition. Thus, Fru-1-P is a physiological inhibitor of pyrophosphatase that acts via a regulatory site in this enzyme.
KEY WORDS: pyrophosphatase, fructose-1-phosphate, regulation, site-directed mutagenesis, allostery