Pyruvate kinase from human skeletal muscle.

Area of Science:

• Biochemistry
• Enzymology
• Human Physiology

Background:

• Pyruvate kinase is a key enzyme in glycolysis.
• Understanding human skeletal muscle pyruvate kinase is crucial for metabolic studies.

Purpose of the Study:

• To describe a simple method for isolating crystalline pyruvate kinase from human skeletal muscle.
• To characterize the purified enzyme's properties.

Main Methods:

• Isolation involved ammonium sulfate fractionation, heat treatment, and crystallization.
• Enzyme activity was measured in triethanolamine and potassium phosphate buffers.
• Molecular weight was determined by gel filtration.

Main Results:

• Two crystal forms of pyruvate kinase were identified with differing solubilities but identical specific activities.
• Specific activity was 245 U/mg protein in triethanolamine buffer and 340 U/mg in potassium phosphate buffer.
• The enzyme is activated by inorganic phosphate and fructose-1,6-bisphosphate and inhibited by ammonium ions.

Conclusions:

• A straightforward method for obtaining crystalline human skeletal muscle pyruvate kinase was established.
• The purified enzyme exhibits significant catalytic activity and a defined quaternary structure.
• Kinetic properties, including activation and inhibition patterns, were elucidated.