Heat of hydrolysis of trimetaphosphate

Geochemical Sources and Availability of Amidophosphates on the Early Earth

“…[11] With the results of these experiments in mind, we investigated the thermodynamics of amidophosphate formation. [14] Theh ydrolysis of triphosphate and pyrophosphate release about 20 kJ mol À1 , [1] suggesting the hydrolysis of amidophosphates is about 30 kJ mol À1 .U sing this assumption, we calculate the range of stability of various N-P-O-H compounds ( Figure 3). However,t he formation of DAPa nd MAP from the amidation of P 4 O 10 and trimetaphosphate, [13] and the lack of formation of DAPa nd MAP from the amidation of triphosphate and pyrophosphate,p rovides reasonable constraints on the formation of PÀNb onds.T he hydrolysis of P 4 O 10 to H 3 PO 4 releases about 420 kJ mol À1 ,o ra bout 70 kJ mol À1 for each bond hydrolyzed, and the hydrolytic opening of the trimetaphosphate ring is about 40 kJ mol À1 .…”

“…31 PNMR spectra of the reaction mixture of Fe 3 Pin25% aqueousa mmonia at room temperaturef or 12 days. Tops pectrum shows the H-decoupled NMR with unlabeled aq 14. NH 3 .Middle spectrum shows the H-decoupled NMR with labeled aq.…”

Pyrophosphate-condensing activity linked to nucleic acid synthesis

“…It has been shown that the heat of hydrolysis is the same, 19 kcal/mol, for both cyclic trimetaphosphate and linear tripolyphosphate (11,12). This value is equal to the,energy of the two high energy bonds in two pyrophosphate molecules undergoing the condensation reaction and shows that the energy of these bonds is not lost for the organism as heat but rather is stored in reaction products.…”

Behavior of polyphosphates in soils

“…Temperatures at which soil enzymtîs begin inactivation usually range from 55 to 65°C (Tabatabai, 1982). (Berg and Gordon, 1960) Partially purified trimetaphosphatase from yeast show optimal activity at pH 7 (Meyerhof et al, 1953). The activity of trimetaphosphatase extracted from intestinal mucosa is op timum at pH 4 (Berg and Gordon, I960), while trimetaphospha tase activity in soybean (Glycine max L. Merrill) hypocotyl extracts is optimum at pH = 4.6 (Stossel et al, 1981).…”

“…Studies on the effect of temperature (Meyerhof et al, 1953) showed that trimetaphosphatase activity in an extract of yeast lost 40% of its activity when incubated for 3 h at 33°C. In other studies, Pierpoint (1957) showed that tri metaphosphatase activity of pea extracts was partially inac tivated by incubating at 48.5°C for 27 min or more.…”