Regulation of d-Fructose 1-Phosphate Kinase by Potassium Ion
Year: 1970
Type: article
Abstract: Purified Aerobacter aerogenes d -fructose 1-phosphate kinase (ATP: d -fructose 1-phosphate 6-phosphotransferase), an enzyme which does not exhibit cooperative kinetics, was activated by K+, Rb+, and NH+4, inhibited by Li+, and not significantly affected by Na+ or Cs+. The enzyme exhibited some activity when assayed in tetramethylammonium-glycylclycine buffer even in the absence of other monovalent cations, suggesting that the requirement for monovalent cations is not absolute. K+ increased the reaction velocity about 4-fold in the presence of excess ATP and d -fructose-1-P, and about 10-fold when both substrates were present at concentrations near their Km values (0.3 m m ). K+ also exerted a much greater activating effect under conditions of inhibiting ATP levels than when Mg++ was present at a sufficiently high level to prevent inhibition by ATP. The K a for K+ (about 3 m m ) was not affected by the Mg++ or ATP concentration, but was increased by decreased levels of d -fructose-1-P. K+ decreased the Km values for both ATP and d -fructose-1-P. These kinetics are consistent with Michaelis-Menten theory and suggest a simple model in which the enzyme exists in two active forms, one form predominating in the presence of K+ and the other predominating in its absence.
Source: Journal of Biological Chemistry
Authors: Virginia Sapico, R.L. Anderson
Institution: Michigan State University
Language: English
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: hybrid
Estimated APC paid: $3,430
OpenAlex ID: W1528409046