- Studies on the biosynthesis of bialaphos. Biochemical mechanism of C-P bond formation: Discovery of phosphonopyruvate decarboxylase which catalyzes the formation of phosphonoacetaldehyde from phosphonopyruvate
-
The biosynthetic step following the phosphoenolpyruvate (PEP) phosphomutase reaction which forms a C-P bond of bialaphos was proven by the identification of phosphonopyruvate (PnPy) and phosphonoacetaldehyde (PnAA) as intermediates in the culture broth of Streptomyces hygroscopicus, a producing organism of bialaphos, and by detection of enzymatic decarboxylation of PnPy to PnAA. Purified PnPy decarboxylase turned out to require thiamine diphosphate and Mg2+ as cofactors. PnPy decarboxylase drives the unfavorable forward reaction to form PnPy catalyzed by PEP phosphomutase and is suggested to be essential to C-P compound biosynthesis.
- Nakashita, Hideo,Watanabe, Kei,Hara, Osamu,Hidaka, Tomomi
-
p. 212 - 219
(2007/10/03)
-
- Synthesis and Hydrolysis Studies of Phosphonopyruvate
-
Phosphonopyruvate (1) is prepared in 56percent yield from triethyl phosphonopyruvate (3) and pKa values of 1.63, 2.40 and 7.41 determined.The stability of phosphonopyruvate is monitored at 75 deg C in aqueous buffers over pH range 0.6 to 8.3.The only products detected are pyruvate and inorganic phosphate.The pH-rate profile shows that the C-P bond is hydrolysed fastest in the monoanion and dianion of phosphonopyruvate, with rate constants of 1.94 * 10-4 s-1 for the monoanion and 1.05 * 10-4 s-1 for the dianion.For the reaction at pH 4.75, where the dianion predominates, ΔH(excit.) is 114.0 kJ mol-1 and ΔS(excit.) is 5.4 J mol-1 K-1, the deuterium isotope effect, kH/kD is 1.08 +/- 0.04, and there is non-selective phosphorylation of methanol and H2O in an equimolar solution of these solvents.These results are consistent with a mechanism of hydrolysis of both the monoanion and dianion that involves a very largely dissociative transition state with monomeric metaphosphate character.
- Freeman, Sally,Irwin, William J.,Schwalbe, Carl H.
-
p. 263 - 267
(2007/10/02)
-