PMID: 1264Dec 1, 1975

Spin-labelled phosphofructokinase. A simple and direct approach to the study of allosteric equilibria under near-physiological conditions

European Journal of Biochemistry
R JonesI O Walker


Rabbit muscle phosphofructokinase, spin-labelled at its most reactive thiol group, has an electron spin resonance spectrum which is very sensitive to the binding of substrates and allosteric effectors. The spectral changes have been interpreted in terms of a concerted allosteric transition between two conformational states with non-exclusive binding of effectors. On this basis MgATP, fructose 6-phosphate plus ATP, and NH+4ions behave as potent positive effectors, inorganic phosphate, sulphate, AMP, fructose 6-phosphate and fructose 1,6-bisphosphate are less potent activators, and free ATP and H+ions are negative effectors, in agreement with the kinetic behaviour, but citrate behaves anomalously. In addition, the allosteric equilibrium can be displaced towards the inhibited state by selectively modifying two further thiol groups. Strong positive cooperativity occurs under suitable conditions with ATP, metal-ATP and fructose 6-phosphate. Biphasic changes of conformation, attributed to binding at the catalytic and inhibitory sites, have been observed in titrations with ATP. The differentiation of the two ATP binding sites arises in the presence of fructose 6-phosphate because of a distinct concerted effect on conformation between ...Continue Reading


Feb 1, 1967·Biochemistry·R G Kemp, E G Krebs
Jan 14, 1968·Journal of Molecular Biology·D BlangyJ MONOD
Jul 1, 1968·Biochemistry·R G Kemp, P B Forest
Jul 1, 1971·Hoppe-Seyler's Zeitschrift für physiologische Chemie·H W Hofer
Apr 11, 1972·European Journal of Biochemistry·K R Leonard, I O Walker
Jun 23, 1972·European Journal of Biochemistry·R JonesI O Walker
Sep 1, 1966·The Biochemical Journal·C I Pogson, P J Randle
Jan 1, 1970·Progress in Biophysics and Molecular Biology·E Whitehead
Nov 14, 1966·Journal of Molecular Biology·M M Rubin, J P CHANGEUX
May 1, 1965·Journal of Molecular Biology·J MONODJ P CHANGEUX

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