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Investigation of the role of the substrate metal ion in the yeast inorganic pyrophosphatase reaction
Author(s) -
Ting Su-Jen,
Dunaway-Mariano Debra
Publication year - 1984
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(84)80179-9
Subject(s) - inorganic pyrophosphatase , catalysis , chemistry , metal , substrate (aquarium) , pyrophosphate , pyrophosphatase , yeast , cofactor , michaelis–menten kinetics , inorganic chemistry , metal ions in aqueous solution , enzyme , organic chemistry , biochemistry , enzyme assay , biology , ecology
The substrate activities of a series of tripositive metal ion‐pyrophosphate complexes with yeast inorganic pyrophosphatase were examined. While the Michaelis constants for these complexes were shown to be between one and two orders of magnitude greater than that of the natural substrate, [Mg(H 2 O) 4 PP i ] 2− , the turnover numbers were in general comparable to that of [Mg(H 2 O) 4 PP i ] 2− . These data suggest that the nature of the metal ion cofactor effects substrate binding but in most cases not catalysis. Thus, the role of the metal ion in catalysis is probably restricted to that of an electron sink.