Synthesis of ascorbyl-2-phosphate by liver enzyme of rainbow trout Oncorhynchus mykiss.

1. Ascorbyl-2-monophosphate was enzymatically formed in the reaction mixture of L-ascorbic acid, pyrophosphate and the homogenate of rainbow trout Oncorhynchus mykiss liver. 2. The liver had the highest activity among the liver, spleen, kidney, stomach, pyloric caeca and intestine. 3. Pyrophosphate, triphosphate, ADP and ATP were good substrates as phosphoryl donors, but phosphoric acid and AMP were poor. 4. The optimum pH and temperature of AP-forming activity in the liver were around 5.0 and 30 degrees C, respectively. 5. The Km values for ascorbic acid and pyrophosphate were 370 and 83 mM, respectively.