590-54-5Relevant articles and documents
Evaluation of Natural and Synthetic Phosphate Donors for the Improved Enzymatic Synthesis of Phosphate Monoesters
Tasnádi, Gábor,Jud, Wolfgang,Hall, Mélanie,Baldenius, Kai,Ditrich, Klaus,Faber, Kurt
supporting information, p. 2394 - 2401 (2018/05/14)
Undesired product hydrolysis along with large amounts of waste in form of inorganic monophosphate by-product are the main obstacles associated with the use of pyrophosphate in the phosphatase-catalyzed synthesis of phosphate monoesters on large scale. In order to overcome both limitations, we screened a broad range of natural and synthetic organic phosphate donors with several enzymes on a broad variety of hydroxyl-compounds. Among them, acetyl phosphate delivered stable product levels and high phospho-transfer efficiency at the lower functional pH-limit, which translated into excellent productivity. The protocol is generally applicable to acid phosphatases and compatible with a range of diverse substrates. Preparative-scale transformations using acetyl phosphate synthesized from cheap starting materials yielded multiple grams of various sugar phosphates with up to 433 g L?1 h?1 space-time yield and 75% reduction of barium phosphate waste. (Figure presented.).
Cloning, expression, purification, cofactor requirements, and steady state kinetics of phosphoketolase-2 from Lactobacillus plantarum
Yevenes, Alejandro,Frey, Perry A.
, p. 121 - 127 (2008/09/20)
The genes xpk1 and xpk2(Δ1-21) encoding phosphoketolase-1 and (Δ1-7)-truncated phosphoketolase-2 have been cloned from Lactobacillus plantarum and expressed in Escherichia coli. Both gene-products display phosphoketolase activity on fructose-6-phosphate in extracts. A N-terminal His-tag construct of xpk2(Δ1-21) was also expressed in E. coli and produced active His-tagged (Δ1-7)-truncated phosphoketolase-2 (hereafter phosphoketolase-2). Phosphoketolase-2 is activated by thiamine pyrophosphate (TPP) and the divalent metal ions Mg2+, Mn2+, or Ca2+. Kinetic analysis and data from the literature indicate the activators are MgTPP, MnTPP, or CaTPP, and these species activate by an ordered equilibrium binding pathway, with Me2+TPP binding first and then fructose-6-phosphate. Phosphoketolase-2 accepts either fructose-6-phosphate or xylulose-5-phosphate as substrates, together with inorganic phosphate, to produce acetyl phosphate and either erythrose-4-phosphate or glyceraldehyde-3-phosphate, respectively. Steady state kinetic analysis of acetyl phosphate formation with either substrate indicates a ping pong kinetic mechanism. Product inhibition patterns with erythrose-4-phosphate indicate that an intermediate in the ping pong mechanism is formed irreversibly. Background mechanistic information indicates that this intermediate is 2-acetyl-TPP. The irreversibility of 2-acetyl-TPP formation might explain the overall irreversibility of the reaction of phosphoketolase-2.
Nucleophilic Reactivity toward Acetyl Chloride in Water
Palling, David J.,Jencks, William P.
, p. 4869 - 4876 (2007/10/02)
Rate constant ratios for the reactions of acetyl chloride with nucleophilic reagents in water containing 2.5percent (v/v) dioxane were determined by product analysis.The rate constants show a small dependence on the basicity of primary amines, with βnuc=0.25, and are assigned to rate-limiting attack of the nucleophile.Pyridines with pKa>5 behave similarly, with βnuc=0.24, but less basic pyridines react more slowly.Several "α-effect" amines and anionic oxygen nucleophiles show small rate enhancements that are attributed to increases in the rate of nucleophilic attack.The rate constants do not fit the N+ correlation equation, and it is concluded that the reactions of nucleophilic reagents with acyl compounds are not satisfactorily correlated by simple modifications of this equation.
