Mechanism of "L"-type pyruvate kinase from rabbit liver. Evidence against phosphoenzyme formation.

The "L"-type pyruvate kinase from rabbit liver does not catalyse exchange between phosphoenol[1-14C]pyruvate and pyruvate at either pH 8.5 or 6.2. Spectrophotometric experiments at pH 8.5 and 6;2 and gel-filtration experiments with [32P]phosphoenolpyruvate at pH 8,5 also fail to demonstrate phosphoenzyme formation. It is concluded that it is very unlikely that the enzyme has a phosphoenzyme mechanism.