Characterization of orthophosphate release from dissolved organic phosphorus by gel filtration and several hydrolytic enzymes

The molecular weight distribution of dissolved organic phosphorus (DOP) and the possible mechanisms of orthophosphate (Pi) release were examined by gel filtration and incubation with some hydrolytic enzymes. Sixty five percent of the DOP appeared to have apparent molecular weights between 300 to 10000 daltons. Less than 10% of the DOP estimated higher molecules greater than 10000 daltons. Alkaline phosphatase released Pi more easily from low molecular weight (< 1500 daltons) DOP than from high molecular weight fractions. While, addition of nucleases or phosphodiesterase alone did not appear Pi release from high molecular weight DOP compounds. Pi release from those DOP compounds increased markedly (more than 30%) when alkaline phosphatase was incubated with nucleases or phosphodiesterase. However, 60% of DOP did not release Pi when alkaline phosphatase was incubated with either enzymes.