- Preparation method of pyridoxal 5-phosphate monohydrate
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The invention provides a preparation method of pyridoxal 5-phosphate monohydrate. The preparation method comprises the following steps: 1, first oxidizing pyridoxine hydrochloride to pyridoxal hydrochloride, adding sodium sulfide, then dropwise adding p-ethoxyaniline to the solution, and carrying out a reaction to produce a pyridoxal hydrochloride Schiff base; 2, adding polyphosphoric acid to thepyridoxal hydrochloride Schiff base, performing a stirring reaction, first hydrolyzing polyphosphoric acid and then performing neutralization with an alkali solution to precipitate a large amount of an orange-red solid after the reaction is completed, and filtering and washing the solid to obtain a pyridoxal 5-phosphate Schiff base; and 3, hydrolyzing the pyridoxal 5-phosphate Schiff base with a 2mol/L of alkali solution, adding an organic solvent for extracting and performing liquid separation, adding a strong acid cation exchange resin into the aqueous phase, performing stirring for 1.0 h and then performing vacuum filtration, and performing freeze drying on the filtrate to obtain pyridoxal 5-phosphate monohydrate. The preparation method of pyridoxal 5-phosphate monohydrate is simple inoperation, mild in reaction conditions, relatively high in purity and yield of the final product, and suitable for industrial application, and has relatively good economic benefits.
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Paragraph 0022; 0033-0035; 0043; 0047-0049; 0053; 0054
(2019/08/20)
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- Thermodynamics and Kinetics of the Reaction between Pyridoxal-5-Phosphate and Hydrazides of 2-Methylfuran-3-Carboxylic and Thiophene-3-Carboxylic Acids in an Aqueous Solution
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Abstract: The stability constants of pyridoxal-5-phosphate hydrazones formed with 2-methylfuran-3-carbohydrazide and thiophene-3-carbohydrazide in an aqueous solution at pH 1.9, 6.6, 7.0, and 7.4 are determined via spectrophotometry. The kinetics of the processes of formation and hydrolysis of the Schiff bases are studied, and the constant of the direct and reverse reactions are calculated from the electronic absorption spectra. The stability constants of the Schiff bases are calculated from their ratio. The thermodynamic parameters of the reaction of formation (log K, ΔH, and TΔS) of both hydrazones at pH 6.6 are determined via calorimetry. The reasons for the differences between the equilibrium constants calculated from the data of spectrophotometric and kinetic experiments are discussed, and the reliability of the obtained results is analyzed.
- Gamov,Zavalishin,Kabirov,Usacheva,Sharnin
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p. 192 - 197
(2019/06/03)
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- Synthesis method of pyridoxal phosphate
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The invention relates to the technical field of chemical synthesis, and concretely discloses a synthesis method of pyridoxal phosphate. The synthesis method of pyridoxal phosphate comprises the following steps: carrying out an oxidation reaction on pyridoxol hydrochloride under the action of active manganese dioxide to prepare pyridoxal hydrochloride; carrying out a condensation reaction on the pyridoxal hydrochloride and N,N-dimethylethylenediamine to obtain a pyridoxal condensate; and carrying out a phosphate esterification reaction on the pyridoxal condensate under the action of polyphosphoric acid to obtain crude pyridoxal phosphate, and purifying and crystallizing the crude pyridoxal phosphate to obtain the pyridoxal phosphate product. The method has the advantages of easily availableraw and auxiliary materials, mild reaction conditions, high yield and environmental protection.
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Paragraph 0023; 0024
(2018/03/01)
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- Method for synthesizing pyridoxal phosphate
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The present invention discloses a method for synthesizing pyridoxal phosphate (5'-pyridoxal phosphate). According to the method, pyridoxine hydrochloride is used as a starting material, and is oxidized under mild reaction conditions to obtain a pyridoxal acidic salt, and a phosphate esterification reaction is carried out with a phosphate esterification reagent to obtain pyridoxal phosphate. According to the present invention, the method has advantages of easily-available raw materials, simple route, low toxicity, less side-reaction, easy product separation, easy product characterizing, high yield and the like.
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Paragraph 0019; 0021; 0024; 0027; 0030; 0033; 0036; 0039
(2019/01/08)
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- Thermodynamical characteristics of the reaction of pyridoxal-5'-phosphate with L-amino acids in aqueous buffer solution
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The reaction of pyridoxal-5'-phosphate with L-isomers of alanine, lysine, arginine, aspartic acid, glutamic acid, and glycine in phosphate buffer solution was studied by absorption spectroscopy and the calorimetry of dissolution at physiological acidity of the medium (pH 7.35). The formation constants of Schiff bases during reactions and changes in Gibbs energy, enthalpy, and entropy were determined. It was shown that the formation constant of the Schiff base and its spectral properties depend on the nature of the bound amino acid. The progress of the reaction with a majority of amino acids is governed by the entropy factor due to the predominant role of the dehydration effect of the reaction center of amino acids during chemical reactions. The intramolecular electrostatic interaction of an ionized phosphate group with the positively charged amino group on the end of the chain of amino acid residue stabilizes the Schiff bases formed by lysine and arginine. The extinction coefficient of the base, equilibrium constant, and the exothermic effect of the reaction then increase. The excess negative charge on the end of the chain of amino acid residues of aspartic and glutamic acids destabilizes the molecule of the Schiff base. In this case, the equilibrium constant decreases and the endothermic effect of the reaction increases. Pleiades Publishing, Ltd., 2011.
- Barannikov,Badelin,Venediktov,Mezhevoi,Guseinov
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scheme or table
p. 16 - 20
(2011/06/18)
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- Understanding non-enzymatic aminophospholipid glycation and its inhibition. Polar head features affect the kinetics of Schiff base formation
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Non-enzymatic aminophospholipid glycation is an especially important process because it alters the stability of lipid bilayers and interferes with cell function and integrity as a result. However, the kinetic mechanism behind this process has scarcely been studied. As in protein glycation, the process has been suggested to involve the formation of a Schiff base as the initial, rate-determining step. In this work, we conducted a comparative kinetic study of Schiff base formation under physiological conditions in three low-molecular weight analogues of polar heads in the naturally occurring aminophospholipids O-phosphorylethanolamine (PEA), O-phospho-dl-serine (PSer) and 2-aminoethylphenethylphosphate (APP) with various glycating carbonyl compounds (glucose, arabinose and acetol) and the lipid glycation inhibitor pyridoxal 5′-phosphate (PLP). Based on the results, the presence of a phosphate group and a carboxyl group in α position respect to the amino group decrease the formation constant for the Schiff base relative to amino acids. On the other hand, esterifying the phosphate group with a non-polar substituent in APP increases the stability of its Schiff base. The observed kinetic formation constants of aminophosphates with carbonyl groups were smaller than those for PLP. Our results constitute an important contribution to understanding the competitive inhibition effect of PLP on aminophospholipid glycation.
- Caldes, Catalina,Vilanova, Bartolome,Adrover, Miquel,Munoz, Francisco,Donoso, Josefa
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experimental part
p. 4536 - 4543
(2011/09/19)
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- Kinetic and thermodynamic study of the reaction of pyridoxal 5′-phosphate with L-tryptophan
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The apparent rate constants for formation (k1) and hydrolysis (k2) of the Schiff bases formed by reaction of pyridoxal 5′-phosphate with L-tryptophan were determined at various pH values, at different temperatures and at constant ionic strength (0.1 M). Also obtained were the elementary rate constants for formation and hydrolysis of the Schiff bases corresponding to the different chemical species present in the media, and the pK values of the Schiff's bases. The activation and thermodynamic parameters for the formation and hydrolysis of the Schiff's bases also were determined. Some of the ΔH0 and ΔS0 values for the individual processes were found to be positive. In basic media the enthalpic factor is unfavorable but the entropie contribution leads to a negative ΔG0. Copyright
- Echevarria, Gerardo R.,Santos, Jose G.,Basagoitia, Andrea,Blanco, Francisco Garcia
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p. 546 - 551
(2007/10/03)
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- Influence of the polarity of the medium on the catalysis of formation, rate of hydrolysis and stability of the Schiff bases formed by pyridoxal 5′-phosphate with L-tryptophan
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The apparent rate constants of formation (k1) and hydrolysis (k2), and the equilibrium constant (KpH), of the Schiff bases formed by pyridoxal 5′-phosphate with L-tryptophan in water and different aqueous ethanol mixtures at a variable pH, 25 °C and an ionic strength of 0.1 M (1 M = 1 mol dm-3) were determined. The individual rate constants of formation and hydrolysis of the Schiff bases of the systems corresponding to the different chemical species present in the medium, as a function of its acidity, were also determined, as were the pK values for the Schiff bases. The influence of the solvent medium on the formation and hydrolysis rate constants of the Schiff bases is discussed.
- Echevarria Gorostidi, Gerardo R.,Santos, Jose G.,Basagoitia, Andrea,Castillo, Marta,Garcia Blanco, Francisco
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p. 335 - 340
(2007/10/03)
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- Schiff's Bases Formed between Pyridoxal 5'-Phosphate and 4-Aminobutanoic Acid. Kinetic and Thermodynamic Study
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The overall and individual kinetic constants of formation (k1 and k1i) and hydrolysis (k2, kOH and k2i) of the Schiff's bases formed between pyridoxal 5'-phosphate (PLP) and 4-aminobutanoic acid (GABA) at 10, 20, 25, 30, and 37 deg C, a variable pH and a constant ionic strength of 0.1 M (1 M = 1 mol dm-3) were determined. The formation of a Schiff's base is an intramolecular acid-catalyzed process. The activation and thermodynamic parameters for the formation and hydrolysis of the Schiff's bases were also determined. ΔH and ΔS for the individual processes were all found to be negative.
- Gorostidi, Gerardo R. Echevarria,Castellanos, M. Gabriela,Perez, Piedad Martin,Santos, Jose G.,Blanco, Francisco Garcia
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p. 523 - 528
(2007/10/03)
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- Determination of the rates of formation and hydrolysis of the schiff bases formed by pyridoxal 5′-phosphate with L-tryptophan and its methyl and n-butyl esters
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The apparent rate constants of the formation (k1) and hydrolysis (k2) of the Schiff bases formed by pyridoxal 5′-phosphate with L-tryptophan and their methyl and n-butyl esters at a variable pH, 25 °C, and an ionic strength of 0.1 M were determined, along with the equilibrium constant (KpH). The individual rate constants of formation and hydrolysis of the Schiff bases of systems corresponding to different chemical species present in the medium as a function of its acidity were also determined, as were the pK values for the Schiff bases. The influence of the α-carboxyl group on the formation and hydrolysis constants of the Schiff bases, and also on their pK values, is demonstrated.
- Echevarria Gorostidi, Gerardo R.,Santos, Jose G.,Basagoitia, Andrea,Garcia Blanco, Francisco
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p. 2471 - 2476
(2007/10/03)
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- On the L-DOPA and carbidopa reactivity against pyridoxal 5′-phosphate. A kinetic study
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The apparent rate constants of the formation (k1) and hydrolysis (k2) of Schiff bases formed by pyridoxal 5′-phosphate (PLP) with L-3,4-dihydroxyphenylalanine (L-DOPA) at a variable pH, 25 °C and an ionic strength of 0.1 M was determined. The individual rate constants for the formation and hydrolysis of Schiff bases corresponding to the different chemical species present in the medium as a function of its acidity were also determined, as were the pKa values for the Schiff bases. The formation and hydrolysis rate constants of the Schiff bases were compared with those of the reaction of PLP with carbidopa (CD), showing that the reactivity of L-DOPA and carbidopa on PLP are the same over the whole pH range studied, and that the hydrolysis rate is somewhat greater for the Schiff bases between PLP and CD than those between PLP and L-DOPA.
- Echevarria Gorostidi, Gerardo R.,Santos, Jose G.,Figueroa, Julia,Blanco, Francisco Garcia
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p. 545 - 549
(2007/10/03)
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- Metal ion inhibition of nonenzymatic pyridoxal phosphate catalyzed decarboxylation and transamination
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Nonenzymatic pyridoxal phosphate (PLP) catalyzed decarboxylations and transaminations have been revisited experimentally. Metal ions are known to catalyze a variety of PLP-dependent reactions in solution, including transamination. It is demonstrated here that the rate accelerations previously observed are due solely to enhancement of Schiff base formation under subsaturating conditions. A variety of metal ions were tested for their effects on the reactivity of the 2-methyl-2-aminomalonate Schiff bases. All were found to have either no effect or a small inhibitory one. The effects of Al3+ were studied in detail with the Schiff bases of 2-methyl-2-aminomalonate, 2-aminoisobutyrate, alanine, and ethylamine. The decarboxylation of 2-methyl-2-aminomalonate is unaffected by metalation with Al3+, while the decarboxylation of 2-aminoisobutyrate is inhibited 125-fold. The transamination reaction of ethylamine is 75-fold slower than that of alanine. Ethylamine transamination is inhibited 4-fold by Al3+ metalation, while alanine transamination is inhibited only 1.3-fold. Metal ion inhibition of Schiff base reactivity suggests a simple explanation for the lack of known PLP dependent enzymes that make direct mechanistic use of metal ions. A comparison of enzyme catalyzed, PLP catalyzed, and uncatalyzed reactions shows that PLP dependent decarboxylases are among the best known biological rate enhancers: decarboxylation occurs 1018-fold faster on the enzyme surface than it does free in solution. PLP itself provides the lion's share of the catalytic efficiency of the holoenzyme: at pH 8, free PLP catalyzes 2-aminoisobutyrate decarboxylation by ～1010-fold, with the enzyme contributing an additional ～108-fold.
- Zabinski,Toney
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p. 193 - 198
(2007/10/03)
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- Production of pyridoxal phosphate by a mutant strain of Schizosaccharomyces pombe.
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Conditions for extracellular production of vitamin B6 compounds (B6), especially pyridoxal 5'-phosphate (PLP) by Schizosaccharomyces pombe leul strain were examined. The productivity was dependent on concentration of L-leucine in the culture medium: 30 mg/l gave the highest concentrations of total B6 and PLP. The viable cells harvested at different growth phases showed different productivity: middle and late exponential phase cells showed the highest productivity of total B6 and PLP, respectively. D-Glucose (1%, w/v) among other sugars gave the best productivity. Supplementation of air and ammonium sulfate significantly increased extracellular production of PLP. Superoxide anion producers, menadione and plumbagin, and H202 increased the productivity of PLP. Cycloheximide inhibited the increase of PLP by the oxidative stress and, in contrast, increased pyridoxine.
- Chumnantana,Hirose,Baba,Yagi
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p. 1789 - 1795
(2007/10/03)
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- Kinetic study of the reaction of pyridoxal 5'-phosphate with hydrazino compounds of pharmacological activity
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The kinetics of the reaction between pyridoxal 5'-phosphate (PLP) with carbidopa, hydralazine, and isoniazid, in aqueous solution at variable pH and constant ionic strength of 0.1M was studied spectrophotometrically. The rate constants of formation and hydrolysis of the resulting Schiff base, and its stability were determined in a wide range of pH. A comparison is made of the formation rate constants with those of PLP with hydrazine. The reactivity shows the sequence isoniazid > hydrazine > carbidopa > hydralazine in the whole range of pH studied. The Schiff bases studied are more stable than those formed by PLP and hexylamine and as stable as those described for the reactions of PLP with poly(L-lysine) or copolypeptides containing L-lysine.
- Echevarria-Gorostidi,Basagoitia,Pizarro,Goldsmid,Blanco,Blanco
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p. 837 - 844
(2007/10/03)
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- ELECTROREDUCTION OF THE SCHIFF BASES FROM PYRIDOXAL-5'-P, PYRIDOXAL AND L-ISOLEUCINE. INFLUENCE OF THE AMINO ACID MOIETY ON THE SCHIFF BASES DERIVED FROM α-AMINO ACIDS
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The electrochemical behaviour of the Schiff bases derived from pyridoxal-5'-P (PLP) and pyridoxal (PL) with L-isoleucine (Ile) has been studied in buffered aqueous solution.The formation of the Schiff base, its dependence on the pH and the electroreduction scheme at different pH values have been compared to those of the Schiff bases derived from L-alanine (Ala) and L-leucine (Leu).The observed differences seem to be produced by a hydrophobic effect of the amino acid moiety.This finding can be helpful for understanding the coenzyme environment on the protein binding site.
- Cambron, Gregoria,Sevilla, Jose M.,Pineda, Teresa,Blazquez, Manuel
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p. 309 - 314
(2007/10/02)
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- Kinetics of the Formation and Hydrolysis of the Schiff's Base of Pyridoxal 5'-Phosphate with Hexylamine in Water-Dioxane
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The rate constants of the reaction between pyridoxal 5'-phosphate and hexylamine have been studied as a function of pH, in water-dioxane mixtures, at 25 deg C, and at an ionic strength of 0.01.We have found that both the solvent effect and the intramolecular acid catalysis effect on the rates of formation, can be acceptably described on the basis of a log k1i versus (pKPi - pKA1) correlation. k1i rate constant for the reaction between free hexylamine and the ionic species of pyridoxal 5'-phosphate with i bound protons (Pi); pKPi pK value of the Pi species; pKA1 pK value of the hexylammonium ion.
- Pino, Isabel M. Plaza del,Llor, Juan,Sanchez-Ruiz, Jose M.
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p. 581 - 584
(2007/10/02)
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- Band-shape Analysis and Resolution of Electronic Spectra of Pyridoxal 5'-Phosphate with Amino Acids
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Formation equilibria of Schiff bases of pyridoxal 5'-phosphate (PLP) and different amino acids have been studied over a wide range of pH.The acid dissociation constant and absorption spectrum of every ionic species have been calculated.The latter has been resolved into components with log-normal curves, to provide a precise description of the band shapes, the peak positions and the area under the curves, which allowed the estimation of tautomerization constants and microscopic acid dissociation constants.Because of the acidity of the α-hydrogen of the amino acids, α-amino acid Schiff bases are in equilibrium with quinonoid forms which are hydrolysed to yield pyridoxamine 5'-phosphate (PMP).This process could explain the bathochromic shifts of the peak position in α-amino acid Schiff bases to the corresponding band in non-α-amino acid systems.
- Vazquez, M. A.,Munoz, F.,Donoso, J.,Blanco, F. Garcia
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p. 275 - 281
(2007/10/02)
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- Catalytic Efficiency of Functionalized Vesicles in the Transamination of Pyridoxal-5'-phosphate with a Hydrophobic Amino Acid
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The transamination reaction of pyridoxal-5'-phosphate (PLP) with N-dodecyl-L-alaninamide (AlaC12) was investigated in an aqueous phosphate-borate buffer at pH 7.0, μ 0.10 (KCl), and 30.0+/-0.1 deg C in the presence of single-walled vesicles of N,N-ditetradecyl-Nα-(6-trimethylammoniohexanoyl)-L-histidinamide bromide (N+C5His2C14).The electrostatic and hydrophobic interactions between the vesicles and the reactants resulted in incorporation of PLP and AlaC12 into polar and hydrophobic domains of the vesicles, respectively, in the Schiff-base formation process.The isomerization of the aldimine Schiff-base to the correspeonding ketimine Schiff-base was confirmed to be the rate-determining step in the transamination process.The reaction site in the vesicular system was found to be equivalent in polarity to dioxane-water (7:3 v/v).However, the overall reaction rate in the vesicles was enhanced 230-fold relative to that in dioxane-water (7:3 v/v).A hydrophobic and suitably polar microenvironment constructed at the reaction site is responsible for such a marked rate-enhancement.In addition, each vesicle of N+C5His2C14 provided functional (imidazolyl) groups in its hydrogen-belt domain to catalyze the intramolecular prototropic shift to yield the ketimine Schiff-base.The microenvironmental effects of molecular assemblies of N,N-ditetradecyl-Nα-(6-trimethylammoniohexanoyl)-L-alaninamide bromide and CTAB on the overall transamination were also discussed.
- Murakami, Yukito,Nakano, Akio,Akiyoshi, Kazunari
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p. 3004 - 3012
(2007/10/02)
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- Rates and Equilibria of Aldimine Formation between Pyridoxal 5'-Phosphate and N-Hexylamine
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The rate and equilibrium constants of the reaction between n-hexylamine and pyridoxal 5'-phosphate have been studied in aqueous solution as a function of pH at 25 +/- 0.1 deg C and at an ionic strength of 0.1.The pH profiles of the observed constants have been explained by protonation of the pyridoxal 5'-phosphate and its Schiff's base.This study shows that there is an intramolecular general acid catalysis of the Schiff's base formation, which can explain why the aldimine is formed at a reasonably high rate at neutral pH, in spite of the low amount of unprotonated reacting amine at this pH.
- Sanchez-Ruiz, Jose M.,Rodriguez-Pulido, Juan M.,Llor, Juan,Cortijo, Manuel
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p. 1425 - 1428
(2007/10/02)
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