TY - JOUR
T1 - Analysis of the cold lability behavior of rabbit muscle phosphofructokinase
AU - Bock, Paul E.
AU - Gilbert, Helen R.
AU - Frieden, Carl
PY - 1975/9/16
Y1 - 1975/9/16
N2 - Rabbit skeletal muscle phosphofructokinase has been previously shown to exhibit the characteristic of cold lability in phosphate buffers at pH values below pH 7 [Bock, P.E. and Frieden, C. (1974) Biochemistry 13, 4191-4196]. Studies of the residual activity as a function of pH, reflecting the equilibrium between active and inactive forms of the enzyme, have been performed. These experiments show that the cold lability can be ascribed to a shift of the apparent pK describing the pH-dependent inactivation to lower pH values at higher temperatures. The apparent pK, Hill interaction coefficient and heat of ionization for this process indicate that the equilibrium between the inactive and active forms of the enzyme may be controlled by the ionization of one or more histidine residues per enzyme subunit. In addition the apparent pK for the pH dependence of the residual activity at constant temperature is influenced by the presence of ligands which are substrates or effectors of the phosphofructokinase reaction.
AB - Rabbit skeletal muscle phosphofructokinase has been previously shown to exhibit the characteristic of cold lability in phosphate buffers at pH values below pH 7 [Bock, P.E. and Frieden, C. (1974) Biochemistry 13, 4191-4196]. Studies of the residual activity as a function of pH, reflecting the equilibrium between active and inactive forms of the enzyme, have been performed. These experiments show that the cold lability can be ascribed to a shift of the apparent pK describing the pH-dependent inactivation to lower pH values at higher temperatures. The apparent pK, Hill interaction coefficient and heat of ionization for this process indicate that the equilibrium between the inactive and active forms of the enzyme may be controlled by the ionization of one or more histidine residues per enzyme subunit. In addition the apparent pK for the pH dependence of the residual activity at constant temperature is influenced by the presence of ligands which are substrates or effectors of the phosphofructokinase reaction.
UR - http://www.scopus.com/inward/record.url?scp=0016754029&partnerID=8YFLogxK
U2 - 10.1016/0006-291X(75)90547-1
DO - 10.1016/0006-291X(75)90547-1
M3 - Article
C2 - 241341
AN - SCOPUS:0016754029
SN - 0006-291X
VL - 66
SP - 564
EP - 569
JO - Biochemical and Biophysical Research Communications
JF - Biochemical and Biophysical Research Communications
IS - 2
ER -