Phosphoenolpyruvate synthesis by fetal guinea-pig liver mitochondria.

Liver mitochondria isolated from fetal and newborn guinea pigs synthesized phosphoenolpyruvate at 4-6 nmol/min per mg protein with 2 mM malate, succinate, and alpha-ketoglutarate as substrates. These rates were 90-110% of that by adult liver mitochondria and were not substantially altered in the second half of gestation or within 24 h after birth. Both palmitoyl- and octanoylcarnitine were inhibitory to phosphoenolpyruvate synthesis in adult and fetal preparations, but free octanoate was inhibitory only in adult liver mitochondria.