At physiological concentrations, AMP increases phosphofructokinase-1 activity compared to fructose 2, 6-bisphosphate in postmortem porcine skeletal muscle

Abstract

Phosphofructokinase-1 (PFK-1) is the most important enzyme controlling postmortem glycolysis in living skeletal muscle and is the most likely candidate for regulation of postmortem glycolysis. We investigated the regulation of PFK-1 activity by F-2, 6-BP and AMP under simulated postmortem conditions in porcine skeletal muscle. Six pigs were harvested and longissimus lumborum samples were collected immediately post-slaughter. PFK-1 activity was assayed using increasing concentrations of F-2, 6-BP or AMP, added to the buffer adjusted to different pH. Both F-2, 6-BP and AMP increased PFK-1 activity with increasing buffer pH from 5.5 to 7.0. A concentration of 50 μM F-2, 6-BP was required to increase PFK-1 activity which is very high compared to physiological concentration in the porcine skeletal muscle. However, physiological concentrations (50-150 μM) of AMP resulted in increased PFK-1 activity compared to 1-2 μM F-2, 6-BP. Thus, AMP may play a greater role in dictating the rate and extent of postmortem muscle glycolysis and pH decline as compared to F-2, 6-BP.

Keywords: AMP; Fructose 2,6-bisphosphate; Phosphofructokinase; Porcine skeletal muscle.