• Bulletin of the Korean Chemical Society
• /
• v.15 no.11
• /
• pp.1001-1003
• /
• 1994

A series of phosphodiesters of p-nitrophenyl phosphoryl derivatives were synthesized and used as a model substrate for phospholipase D (PLD). The phosphodiester substrates were synthesized from p-nitrophenyl phosphorodichloridate and corresponding alcohols with different chain lengths and polar groups. To measure the activity of PLD, either spectroscopic method for p-nitrophenol or pH-stat titration method was employed. For each substrate, effects of substrate concentration, pH, and $Ca^{2+}$ ion were examined. The kinetic parameters $V_{max}$ for the different substrates were varied depending on the chain lengths or charge of the alcohols. No calcium effect was observed in the hydrolysis of neutral and negatively charged alcohol derivatives, while positively charged choline derivative showed a strong $Ca^{2+}$ ion dependence.

• Applied Biological Chemistry
• /
• v.37 no.6
• /
• pp.447-450
• /
• 1994

Rate of hydrolysis ethylene phosphate, dimethylphosphate and hydroxyethylmethylphosphate in neutral water have been measured. Hydrolysis of ethylene phosphate proceeds with P-0 bond cleavage $(k_{obs}=3{\times}10^{-7}s^{-1}\;at\;100^{\circ}C,\;{\Delta}H{\neq}=24\;kcal,\;{\Delta}S{\neq}=25.5\;eu)$. In constrast, hydrolysis of dimethylphosphate proceeds with C-O bond cleavage $(k_{obs}=3{\times}10^{-7}s^{-1}\;at\;150^{\circ}C)$. The rate constant for P-O bond cleavage of dimethylphosphate is estimated at $1{\times}10^{-11}s^{-1}\;at\;150^{\circ}C,\;({\Delta}H{\neq}=36\;kcal,\;{\Delta}S{\neq}=25.5\;eu)$. A phosphodiesterase catalyzed hydrolysis of dimethylphosphate is $10^{17}$ times faster than the simple water rate. The observed rate of hydrolysis of hydroxyethylmethylphosphate is comparable to that of dimethylphosphate indicating C-O bond cleavage $(k_{obs}=6{\times}10^{-7}s^{-1}\;at\;150^{\circ}C)$.

• Journal of the Korean Magnetic Resonance Society
• /
• v.3 no.1
• /
• pp.1-11
• /
• 1999

Localized in vivo 31P NMR spectroscopy was applied to evaluate the postmortem catabolism of high energy phosphates in rabbit skeletal muscle tissue. In the premortem processes all of the important high energy phosphate metabolites were characterized, and particularly phosphocreatine (PCr) resonance signal was the strongest. In the immediate phases of the postmortem processes the signal intensities of PCr, phosphomonoesters (PME), phosphodiesters(PDE), $\alpha$-, $\beta$- and ${\gamma}$-adenosine triphosphate (ATP) resonance began to decrease while the signal intensity of inorganic phosphorus (Pi) resonance began to increase. The present study suggests that localized in vivo 31P NMR spectroscopy may provide more precise biochemical information of the early postmortem period based on the metabolic alterations of phosphate. The unique ability of localized in vivo 31P NMR spectroscopy to offer noninvasive information about tissue biochemistry in animals as well as human may have an impact on thanatochronology and medicolegal science.