Thermal inactivation of skeletal muscle phosphorylase b: protective effect of the specific ligands.
The kinetics of the thermal inactivation of rabbit skeletal muscle phosphorylase b have been studied. Under the condition used (0.08 M HEPES, pH 6.8, 75 mu g/ml phosphorylase b) the enzyme quickly loses its activity at the temperature higher then 49 degrees C. All the specific ligands tested (substrate -glucose 1-phosphate, competitive inhibitor - glucose, allosteric activator - AMP, and allosteric inhibitors - glucose 6-phosphate and FMN) have the pronounced protective effect. The strongest protective action have glucose 6-phosphate and FMN. Quantitative analysis of the inactivation rate constant versus ligand concentration curves allow the enzyme affinity for ligands to be characterized.
Kornilaev
B A
BA
A. N. Bach Institute of Biochemistry, Russian Academy of Sciences, Moscow, Russia.
Kurganov
B I
BI
Eronina
T B
TB
Livanova
N B
NB
D000249:Adenosine Monophosphate; D000494:Allosteric Regulation; D000818:Animals; D004789:Enzyme Activation; D005486:Flavin Mononucleotide; D019298:Glucose-6-Phosphate; D008024:Ligands; D018482:Muscle, Skeletal / Q000201:enzymology*; D010763:Phosphorylase b / Q000378:metabolism*; D011817:Rabbits; D013696:Temperature
D008024:Ligands; D000249:Adenosine Monophosphate; D019298:Glucose-6-Phosphate; D005486:Flavin Mononucleotide; D010763:Phosphorylase b