Thiamine Molecule Research Articles

Thiamine-modified octamolybdate catalyzes solvent-free stereoselective olefin epoxidation with TBHP

Simple stirring of an acidic aqueous solution (pH=3) containing sodium molybdate and thiamine hydrochloride (VB1) at room temperature resulted in an octamolybdate-containing VB1 (MoB1) material as an efficient and cost-effective epoxidation catalyst using tert‑butyl hydroperoxide (TBHP) under solvent-free condition. The stereospecific stilbene oxidation (>99 %) observed in the presence of MoB1 can be originated from the steric hindrance of some groups on the thiamine molecule and π–π stacking interactions of its pyrimidine and/or thiazole rings with phenyl rings of stilbenes. Further olefins such as cyclooctene, indene, 1-octene, and styrenes are efficiently oxidized using MoB1/TBHP catalytic system. The catalyst is composed of two thiaminium dications (C12H18N4OS)2+ and one Mo8O264– tetraanion based on different characterization techniques and chemical compositional analyses. Field Emission Scanning Electron Microscope (FE-SEM) images shows a sheet-like nanostructure for MoB1 comprising layers with thicknesses ranging from 50 to 500 nm. It exhibits a heterogeneous nature in catalysis evidenced by hot filtration test and ICP-OES analysis. X-ray photoelectron spectroscopy (XPS) indicates minor contributions of Mo in the oxidation states +V and +IV in addition to MoVI attributed to partial electron transfer from VB1 to Mo8O264–. The scavenging experiments support the presence of radical species during catalysis, while, they do not damage the structural integrity of the MoB1 catalyst based on the recycling experiments and FT-IR spectra.

Effect of ultraviolet on thiamine and thiamine disulfides

In a neutral medium, the exposure of thiamine disulfide to the ultraviolet of solar radiation (as well as to the ultraviolet radiation of mercury lamp with λ > 300 nm) results in the formation of a thiamine molecule with closed thiazole ring and a molecule of thiamine thiazolone. Asymmetric thiamine disulfides, e.g., thiamine propyl disulfide, on exposure to ultraviolet (UVA range) produced thiamine and propyl disulfides. Thiamine and thiazolone of thiamine are stable upon exposure to light of 320-400 nm (UVA range). UV irradiation within spectral range of 200-300 nm results in further photodestruction of thiamine and thiamine thiazolone and production of 2-methyl-4-amino-5aminomethyl-pyrimidine as the main photoproduct. The possibility to use thiamine disulfide derivatives as a promising class of anti-cataract drugs as well as drugs to decrease the toxic effect of ultraviolet radiation on human retina is discussed.

THIAMINASE ACTIVITY OF MYOGLOBIN OXOFERRYL FORMS

Thiamine oxidation chemistry in presence of metmyoglobin and hydrogen peroxide is quite complex and different products can be formed. Incubation of thiamine with metmyoglobin and hydrogen peroxide can result in splitting of thiamine molecule at carbon atom of the methylene bridge and production of aminopyrimidine and thiazole components as separate molecules or in formation of thiochrome, thiamine disulfide, oxodihydrothiochrome, and thiaminethiazolone. Oxidative transformation of thiamine phosphate esters in presence of metmyoglobin and hydrogen peroxide gives similar products however thiaminase activity, i.e. splitting of the molecules into aminopyrimidine and thiazole phosphate parts, is much higher in this case. Addition of tyrosine or paracetamol to incubation mixture inhibits thiaminase activity and formation of disulfides, but yield of thiochrome or thiochrome phosphates increases. Identification of products of thiamine (or its phosphate esters) oxidation in the presence of metmyoglobin and hydrogen peroxide was performed using HPLC, mass-spectrometry and spectral-fluorescent methods. Role of oxoferryl forms of myoglobin in degradation of thiaminediphosphate, cofactor of the important enzymes of carbohydrate metabolism, by thiaminase mechanism is discussed.

Redesigning thiamin synthesis: Prospects and potential payoffs

Thiamin is essential for plant growth but is short-lived in vivo and energetically very costly to produce – a combination that makes thiamin biosynthesis a prime target for improvement by redesign. Thiamin consists of thiazole and pyrimidine moieties. Its high biosynthetic cost stems from use of the suicide enzyme THI4 to form the thiazole and the near-suicide enzyme THIC to form the pyrimidine. These energetic costs lower biomass yield potential and are likely compounded by environmental stresses that destroy thiamin and hence increase the rate at which it must be made. The energy costs could be slashed by refactoring the thiamin biosynthesis pathway to eliminate the suicidal THI4 and THIC reactions. To substantiate this design concept, we first document the energetic costs of the THI4 and THIC steps in the pathway and explain how cutting these costs could substantially increase crop biomass and grain yields. We then show that a refactored pathway must produce thiamin itself rather than a stripped-down analog because the thiamin molecule cannot be simplified without losing biological activity. Lastly, we consider possible energy-efficient alternatives to the inefficient natural THI4- and THIC-mediated steps.

Association of Spherical Porous Nanocluster Keplerate-Type Polyoxometalate Mo72Fe30 with Biologically Active Substances

The peculiarities of formation of ionic associates of the spherical porous nanocluster polyoxometalate [Mo72Fe30O252(CH3COO)12{Mo2O7(H2O)}2{H2Mo2O8(H2O)}(H2O)91] ~ 150H2O with biologically active substances, in particular, thiamine chloride using the methods of UV/Vis spectroscopy, pH-metry, laser light scattering (the measurement of Zeta potential and particle size distribution), Raman spectroscopy, infrared spectroscopy and inductively coupled plasma atomic emission spectroscopy has been studied. The location of thiamine molecules on POM’s surface is given. The solubility product of associate was estimated. The formation of molecular associates of polyoxometalate with insulin, albumin has been shown. Using the meglumine acridonacetate the influence of complexing agents on the possibility of obtaining associates on the basis of [Mo72Fe30O252(CH3COO)12{Mo2O7(H2O)}2{H2Mo2O8(H2O)}(H2O)91] ~ 150H2O has been studied.

Limitation of thiamine pyrophosphate supply to growing Escherichia coli switches metabolism to efficient D-lactate formation.

Efficient production of D-lactate by engineered Escherichia coli entails balancing cell growth and product synthesis. To develop a metabolic switch to implement a desirable transition from cell growth to product fermentation, a thiamine auxotroph B0013-080A was constructed in a highly efficient D-lactate producer E. coli strain B0013-070. This was achieved by inactivation of thiE, a gene encoding a thiamine phosphate synthase for biosynthesis of thiamine monophosphate. The resultant mutant B0013-080A failed to grow on the medium in the absence of thiamine yet growth was restored when exogenous thiamine was provided. A linear relationship between cell mass formation and amount of thiamine supplemented was mathematically determined in a shake flask experiment and confirmed in a 7-L bioreactor system. This calculation revealed that ∼ 95-96 thiamine molecules per cell were required to satisfy cell growth. This relationship was employed to develop a novel fermentation process for D-lactate production by using thiamine as a limiting condition. A D-lactate productivity of 4.11 g · L(-1) · h(-1) from glycerol under microaerobic condition and 3.66 g · L(-1) · h(-1) from glucose under anaerobic condition was achieved which is 19.1% and 10.2% higher respectively than the parental strain. These results revealed a convenient and reliable method to control cell growth and improve D-lactate fermentation. This control strategy could be applied to other biotechnological processes that require optimal allocation of carbon between cell growth and product formation.

Thiamine triphosphatase and the CYTH superfamily of proteins

The CYTH superfamily of proteins was named after its two founding members, the CyaB adenylyl cyclase from Aeromonashydrophila, and the human 25-kDa thiamine triphosphatase (ThTPase). Members of this superfamily of proteins exist in all organisms, including bacteria, archaeons, fungi, plants, and animals (except birds), and can be traced back to the last universal common ancestor. Their sequences include several charged residues involved in divalent cation and triphosphate binding. Indeed, all members of the CYTH superfamily that have been characterized act on triphosphorylated substrates and require at least one divalent metal cation for catalysis. In most cases, the enzyme-substrate complex adopts a tunnel-like (β-barrel) conformation. The Nitrosomonaseuropaea, Escherichiacoli and Arabidopsisthaliana CYTH proteins are specific inorganic tripolyphosphatases. We propose that inorganic tripolyphosphate, the simplest triphosphate compound, is the primitive substrate of CYTH proteins, other enzyme activities, such as adenylate cyclase (in A.hydrophila and Yersiniapestis), mRNA triphosphatase (in fungi and protozoans), and ThTPase (in metazoans), being secondary acquisitions. ThTPase activity is not limited to mammals, as sea anemone and zebrafish CYTH proteins are specific ThTPases. The acquisition of this enzyme activity is linked to the presence of a tryptophan involved in the binding of the thiazolium heterocycle of the thiamine molecule. Furthermore, we propose a conserved catalytic mechanism between a bacterial inorganic tripolyphosphatase and metazoan ThTPases, based on a catalytic dyad comprising a lysine and a tyrosine, explaining the alkaline pH optimum of these enzymes.

Carbenes in Their Natural Habitat

Chemistry![Figure][1] CREDIT: MEYER ET AL., NAT. CHEM. BIOL. 9 , 488 (2013) Over 50 years ago, Ronald Breslow suggested that thiamin may adopt a short-lived reactive carbene structure—with a divalent carbon center stabilized by flanking sulfur and nitrogen—during the enzymatic reaction cycle of vitamin B1. In the interim time, chemists have synthesized a huge range of stabilized cyclic carbenes, most of which are derived from imidazole (with two flanking nitrogens) rather than thiazole frameworks. These N-heterocyclic carbenes, or NHCs, are frequently stable and possible to isolate and have been applied as ligands in transition-metal catalysts. They are also versatile catalysts in their own right. Nonetheless, the question of whether thiamin itself reacts as a catalytic carbene in native context has remained open. Meyer et al. present a high-resolution (1.06 A) crystal structure of pyruvate oxidase with bound phosphate (an unreactive analog of the pyruvate substrate), and the associated thiamin molecule shows clear evidence of carbene character. The carbon center in question appears to be deprotonated while lacking the excess electron density indicative of a carbanion. Nat. Chem. Biol. 9 , 488 (2013). [1]: pending:yes

3D-RISM-Dock: A New Fragment-Based Drug Design Protocol.

We explore a new approach in the rational design of specificity in molecular recognition of small molecules based on statistical-mechanical integral equation theory of molecular liquids in the form of the three-dimensional reference interaction site model with the Kovalenko-Hirata closure (3D-RISM-KH). The numerically stable iterative solution of conventional 3D-RISM equations includes the fragmental decomposition of flexible ligands, which are treated as distinct species in solvent mixtures of arbitrary complexity. The computed density functions for solution (including ligand) molecules are obtained as a set of discrete spatial grids that uniquely describe the continuous solvent-site distribution around the protein solute. Potentials of mean force derived from these distributions define the scoring function interfaced with the AutoDock program for an automated ranking of docked conformations. As a case study in terms of solvent composition, we analyze cooperative interactions encountered in the binding of a flexible thiamine molecule to the prion protein at near-physiological conditions. The predicted location and residency times of computed binding modes are in excellent agreement with the available experimental data.

Inhibition of mammalian carbonic anhydrase isoforms I, II and VI with thiamine and thiamine-like molecules

Here we determined the in vitro inhibitory effects of 5-(2-hydroxyethyl)-3,4-dimethylthiazolium iodide (1), 3-Benzyl-5-(2-hydroxyethyl)-4-methylthiazolium chloride (2) and thiamine (3) on human erythrocyte carbonic anhydrase I, II isozymes (hCA I and hCA II) and secreted isoenzyme CA VI. KI values ranged from 0.38 to 2.27 µM for hCA I, 0.085 to 0.784 µM for hCA II and 0.062 to 0.593 µM for hCA VI, respectively. The compounds displayed relatively strong actions on hCA II, in the same range as the clinically used sulfonamidesethoxzolamide, zonisamide and acetazolamide.

Tiamina i jej pochodne w regulacji metabolizmu komórek

For over 70 years thiamine (vitamin B1) has aroused the interest of biologists, biochemists and medical doctors because of its multilateral participation in key biochemical and physiological processes. The thiamine molecule is composed of pyrimidine and thiazole rings which are linked by a methylene bridge. It is synthesized by microorganisms, fungi and plants, whereas animals and humans have to obtain it from food. There are several known forms of vitamin B1 inside cells: free thiamine, three phosphate esters (mono-, di-, and triphosphate), and the recently found adenosine thiamine triphosphate. Thiamine has a dual, coenzymatic and non-coenzymatic role. First of all, it is a precursor of thiamin diphosphate, which is a coenzyme for over 20 characterized enzymes which are involved in cell bioenergetic processes leading to the synthesis of ATP. Moreover, these enzymes take part in the biosynthesis of pentose (required for the synthesis of nucleotides), amino acids and other organic compounds of cell metabolism. On the other hand, recent discoveries show the non-coenzymatic role of thiamine derivatives in the process of regulation of gene expression (riboswitches in microorganisms and plants), the stress response, and perhaps so far unknown signal transduction pathways associated with adverse environmental conditions, or transduction of nerve signals with participation of thiamine triphosphate and adenosine thiamine triphosphate. From the clinical point of view thiamine deficiency is related to beri-beri, Parkinson disease, Alzheimer disease, Wernicke-Korsakoff syndrome and other pathologies of the nervous system, and it is successfully applied in medical practice. On the other hand, identifying new synthetic analogues of thiamine which could be used as cytostatics, herbicides or agents preventing deficiency of vitamin B1 is currently the major goal of the research. In this paper we present the current state of knowledge of thiamine and its derivatives, indicating the participation of these compounds in the regulation of cell metabolism at both the coenzymatic and non-coenzymatic level.

Insights into the dehydration behavior of thiamine hydrochloride (Vitamin B1) hydrates: Part I

Thiamine hydrochloride (Vitamin B1, THCl) can exist as a nonstoichiometric hydrate (NSH) and as a hemihydrate (HH). NSH can contain up to ∼1 molar equivalent of water and be dehydrated to an isomorphic desolvate (ID) with minimal change in lattice structure. Crystallographic and spectroscopic techniques were used to characterize the influence of structure and mobility on NSH dehydration. Dehydration was accompanied by lattice contraction, as noted by a decrease in the d-spacings. Dehydration also led to the development of surface cracks parallel to the (101―) and (102―) planes in the NSH single crystal, as observed by hot stage microscopy. Step-wise dehydration of NSH produced gradual shifts in XRPD and SSNMR peaks, indicating that NSH (with ∼1 mole water) and ID represent the two extremes of a continuum in the hydration state. Variable temperature 13C SSNMR studies showed that water molecules move rapidly at room temperature within the NSH crystal lattice, and the thiamine molecules transiently exist in distinct hydrated and dehydrated states. It is hypothesized that, despite the lack of continuous hydration channels in the NSH crystal lattice, cooperative deformation of the thiamine molecules allows a nondisruptive departure of water molecules from the lattice during dehydration. © 2009 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 99:816–827, 2010

A novel biosensor based on activation effect of thiamine on the activity of pyruvate oxidase

A biosensor based on pyruvate oxidase (POX) enzyme was developed for the investigation of the effect of thiamine (vitamin B 1) molecule on the activity of the enzyme. The biosensor was prepared with a chemical covalent immobilization method on the dissolved oxygen (DO) probe by using gelatin and cross-linking agent, glutaraldehyde. POX catalyzes the degradation of pyruvate to acetylphosphate, CO 2 and H 2O 2 in the presence of phosphate and oxygen. Thiamine is an activator for POX enzyme and determination method of the biosensor was based on this effect of thiamine on the activity of the enzyme. The biosensor responses showed increases in the presence of thiamine. Increases in the biosensor responses were related to thiamine concentration. Thiamine determination is based on the assay of the differences on the biosensor responses on the oxygenmeter in the absence and the presence of thiamine. The biosensor response depend linearly on thiamine concentration between 0.025 and 0.5 μM with 2 min response time. In the optimization studies of the biosensor the most suitable enzyme amount was found as 2.5 U cm −2 and also phosphate buffer (pH 7.0; 50 mM) and 35 °C were obtained as the optimum working conditions. In the characterization studies of the biosensor some parameters such as activator and interference effects of some substances on the biosensor response and reproducibility were carried out.

Interactions of thiamine with polymeric halogenocadmate anions in the organic–inorganic hybrid compound (thiaminium)[Cd3Br4.4Cl3.6

The structure of poly[3-[(4-amino-2-methylpyrimidin-1-ium-5-yl)methyl]-5-(2-hydroxyethyl)-4-methylthiazolium octa-mu-bromo/chloro(4.4/3.6)-tricadmate(II)], [(C12H18N4OS)[Cd3 Br4.41Cl3.59]]n consists of hydrogen-bonded thiamine molecules and polymeric cadmium bromide/chloride anions in an organic-inorganic hybrid fashion. The one-dimensional anion ribbons are formed by edge-sharing octahedra and vertex-sharing tetrahedra. Thiamine molecules adopting the S conformation are linked to anions via three types of interactions, namely an N(amino)-H...anion...thiazolium bridging interaction, an N(pyrimidine)-H...anion hydrogen bond and an O(hydroxy)-H...anion hydrogen bond.

Raman and surface-enhanced Raman study of thiamine at different pH values

Raman spectroscopy was employed for evidencing the protonated and unprotonated thiamine molecular species in aqueous solutions at different acid and basic pH. The recorded Raman spectra were assigned on the basis of density functional theory (DFT) calculations. Also, at different pH values of the gold sol, the adsorption of the two molecular species to colloidal metal particles was monitored by means of surface-enhanced Raman scattering (SERS). At pH values of 3, 4 and 5, the SERS spectra revealed the coexistence of unprotonated and protonated thiamine molecules adsorbed on the gold surface. The adsorption was concluded taking place through the N3′ and N1′ atoms from the pyrimidine moiety of thiamine. The orientation to the gold surface of the protonated and unprotonated thiamine molecular species was discussed.

The melaminophenyl arsenicals melarsoprol and melarsen oxide interfere with thiamine metabolism in the fission yeast Schizosaccharomyces pombe.

The melaminophenyl arsenical melarsoprol is the main drug used against late-stage sleeping sickness caused by Trypanosoma brucei subspecies. Its active metabolite in the human body is melarsen oxide. Here, it is shown that this metabolite inhibits growth of the fission yeast Schizosaccharomyces pombe and that its toxicity can be abolished efficiently by thiamine (vitamin B(1)), thiamine analogues, and the pyrimidine moiety of the thiamine molecule. Uptake of melarsen oxide is mediated by a membrane protein (car1p), which is involved in the uptake of thiamine and its pyrimidine moiety. Melarsoprol is taken up by cells in a thiamine- and car1p-dependent manner but is not toxic to cells.

Cordycepin in Schizosaccharomyces pombe: effects on the wild type and phenotypes of mutants resistant to the drug.

The adenosine analogue cordycepin (3'-deoxyadenosine) inhibits growth and causes aberrant cell morphology in the fission yeast, Schizosaccharomyces pombe. Exogenously added thiamine, the pyrimidine moiety of the thiamine molecule, and adenine alleviate its growth-disturbing effect. At concentrations that do not inhibit growth, the drug reduces mating and sporulation and causes a decrease in the mRNA level of gene ste11 and the ste11-dependent gene, mei2. The mating- and sporulation-inhibiting effect of cordycepin is overcome by adenine. A mutant disrupted for the ado1 gene encoding adenosine kinase exhibits a cordycepin-resistant and methionine-sensitive phenotype, excretes adenosine into the medium and mates and sporulates poorly in the presence of adenine. A S. pombe mutant containing a frameshift mutation at the beginning of the carboxy-terminal half of gene ufd1 (the Saccharomyces cerevisiae UFD1 homologue) is cordycepin-resistant and sterile. Strains disrupted for the ufd1 gene only form microcolonies.

Ternary systems of Zn 2+ and Cd 2+, 2-(α-hydroxyethyl)thiamin pyrophosphate (HETPP) and the pentapeptide Asp-Asp-Asn-Lys-Ile. : Implications for the mechanism of thiamin enzymes

To obtain structural information on the active-site of thiamin-dependent enzymes in solution, the interaction of Zn 2+ and Cd 2+ ions with the pentapeptide Asp-Asp-Asn-Lys-Ile surrounding the thiamin pyrophosphate moiety in the transketolase enzyme, and the tertiary Zn 2+/or Cd 2+–pentapeptide–HETPP systems have been studied by NMR spectroscopy in aqueous solutions at physiological pH. The HETPP, 2-(α-hydroxyethyl)thiamin pyrophosphate, represents an active intermediate of thiamin catalytic cycle formed after the addition of pyruvate substrate on thiamin molecule. The present data show the existence of the tertiary metal–[pentapeptide]–[HETPP] complexes at physiological pH, where the metal coordination sphere is completed by both peptide backbone and HETPP molecule. The metal coordinated HETPP molecule adopts the so-called S conformation in solution. The importance of the present findings correlated with previous results is discussed and possible functional implications are suggested.

Metal ion and anion coordination in the thiamine–[Pt II(NO 2) 4] 2− system. Structures of a metal complex, Pt(thiamine)(NO 2) 3, and two salts, (H-thiamine)[Pt(NO 2) 4]·2H 2O and (thiamine monophosphate) 2[Pt(NO 2) 4]·2H 2O

Reaction of thiamine or thiamine monophosphate (TMP) with K 2Pt(NO 2) 4 afforded a metal complex, Pt(thiamine)(NO 2) 3 ( 1), and two salt-type compounds, (H-thiamine)[Pt(NO 2) 4]·2H 2O ( 2) and (TMP) 2[Pt(NO 2) 4]·2H 2O ( 3), which were structurally characterized by X-ray diffraction. In 1, the square-planar Pt 2+ ion is coordinated to the pyrimidine N(1′), a usual metal-binding site, and three NO 2 − groups. The thiamine molecule exists as a monovalent cation in 1 and a divalent cation in 2 while the TMP molecule is a monovalent cation in 3. In each compound, thiamine or TMP adopts the usual F conformation and forms two types of host–guest-like interactions with anions, which are of the bridging forms, C(2)H⋯anion⋯pyrimidine-ring and N(4′1)H⋯anion⋯thiazolium-ring. In 3, there is an additional anion–bridging interaction between the pyrimidine and thiazolium rings of TMP, being of the form C(6′)H⋯anion⋯thiazolium-ring. The salts 2 and 3 show similar hydrogen-bonded cyclic dimers of thiamine or TMP between which the anions are held. Results are compared with those of the other thiamine–platinum complexes.

Host-guest-like thiamine-anion complexation in thiaminium bis(tetrafluoroborate).

In the title compound, 3-[(4-amino-2-methyl-5-pyrimidin-1-io)methyl]-5-(2-hydroxyethyl)-4-methylthiazolium(2+) bis(tetrafluoroborate), C(12)H(18)N(4)OS(2+).2BF(4)(-), the divalent thiamine cation (in the F conformation) is associated with BF(4)(-) anions via two characteristic bridging interactions between the thiazolium and pyrimidinium rings, i.e. C-H...BF(4)(-)...pyrimidinium and N-H...BF(4)(-)...thiazolium interactions. Thiamine molecules are linked by N-H...O hydrogen bonds to form a helical chain structure.