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The ligand-dependent susceptibility to heat inactivation and to tryptic digestion and the intrinsic fluorescence of the fructose 1,6-bisphosphate-activated pyruvate kinase from Escherichia coli were investigated in the absence and in the presence of physiological ligands. With respect to the enzyme alone, binding of the allosteric activator fructose 1,6-bisphosphate makes the protein sensitive to tryptic attack and thermolabile, while binding of phosphoenolpyruvate and Mg2+, but not of either ligand separately, induces in the enzyme a highly thermostable conformation, the attainment of which does not require an ordered binding sequence of the two ligands. The apparent loosening of the enzyme structure induced by fructose bisphosphate suggests that the activation it exerts at low phosphoenolpyruvate concentration might be due to an increased accessibility of substrate to the active site.
M L Speranza, and
G Valentini, and
G Ferri, and
M Malcovati
January 1979,
The Italian journal of biochemistry,
M L Speranza, and
G Valentini, and
G Ferri, and
M Malcovati
January 1982,
Methods in enzymology,
M L Speranza, and
G Valentini, and
G Ferri, and
M Malcovati
September 1977,
European journal of biochemistry,
M L Speranza, and
G Valentini, and
G Ferri, and
M Malcovati
February 1998,
Structure (London, England : 1993),
M L Speranza, and
G Valentini, and
G Ferri, and
M Malcovati
January 1991,
Acta biochimica Polonica,
M L Speranza, and
G Valentini, and
G Ferri, and
M Malcovati
February 1980,
The Biochemical journal,
M L Speranza, and
G Valentini, and
G Ferri, and
M Malcovati
November 1992,
The EMBO journal,
M L Speranza, and
G Valentini, and
G Ferri, and
M Malcovati
May 2002,
Molecular microbiology,
M L Speranza, and
G Valentini, and
G Ferri, and
M Malcovati
June 1983,
The Biochemical journal,
M L Speranza, and
G Valentini, and
G Ferri, and
M Malcovati
March 1986,
The Biochemical journal,
