Enzymatically hydrolysable phosphorus

Shan, Y., McKelvie, I.D. and Hart, B.T. (1994) Determination of alkaline phosphatase hydrolysable-phosphorus in natural water systems by enzymatic flow injection. Limnology and Oceanography 39, 1993-2000. 

Phosphodiesters include nucleic acids, phospholipids, and others. These compounds are labile and actively involved in biological cycling of phosphorus and are known to be important sources of DIP in aquatic environment (Chrost and Siuda, 2002). Turnover time of these compounds is short because of their rapid enzymatic hydrolysis by phosphodiesterases. The absolute quantity of DIP release during the hydrolysis of these compounds has not been determined in wetland soils. In aquatic environment, phosphodiesters were found to be one of the major sources of DIP in the water column. For example, enzymatically hydrolysable extracellular DNA contributes approximately... 

Of the esters, starch phosphate is produced by reaction with phosphorus oxychloride, polyphosphates, or metaphosphates a cross-bonded product results. Total degree of substitution is determined by measuring the phosphorus content, and the mono- to disubstitution ratio can be calculated by potentio-metric titration. Allowance is made for the natural phosphorus content of the starch. Treatment of starch with acetic anhydride produces starch acetate, which has improved paste stability over native starch. The acetyl group is very labile, and hydrolyses readily under mild alkaline conditions. When a known amount of alkali is used, the excess can be titrated and the ester function measured. This is not specific, however, and a method based on an enzymatic measurement of the acetate has been developed in an ISO work group. The modified starch is hydrolyzed under acidic conditions, which releases acetic acid and permits filtration of the resulting solution. Acetic acid is then measured by a commercially available enzyme test kit. Both bound and free acetyl groups can be measured, and the method is applicable... 

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