Toward the Development of Dual‐Targeted Glyceraldehyde‐3‐phosphate Dehydrogenase/Trypanothione Reductase Inhibitors against Trypanosoma brucei and Trypanosoma cruzi

A significant improvement in the treatment of trypanosomiases has been achieved with the recent development of nifurtimox–eflornithine combination therapy (NECT). As an alternative to drug combinations and as a means to overcome most of the antitrypanosomatid drug discovery challenges, a multitarget drug design strategy has been envisaged. To begin testing this hypothesis, we designed and developed a series of quinone–coumarin hybrids against glyceraldehyde‐3‐phosphate dehydrogenase/trypanothione reductase (GAPDH/TR). These enzymes belong to metabolic pathways that are vital to Trypanosoma brucei and Trypanosoma cruzi, and have thus been considered promising drug targets. The synthesized molecules were characterized for their dual‐target antitrypanosomal profile, both in enzyme assays and in in vitro parasite cultures. The merged derivative 2‐{[3‐(3‐dimethylaminopropoxy)‐2‐oxo‐2H‐chromen‐7‐yl]oxy}anthracene‐1,4‐dione ( 10 ) showed an IC₅₀ value of 5.4 μM against TbGAPDH and a concomitant K_i value of 2.32 μM against TcTR. Notably, 2‐{4‐[6‐(2‐dimethylaminoethoxy)‐2‐oxo‐2H‐chromen‐3‐yl]phenoxy}anthracene‐1,4‐dione (compound 6 ) displayed a remarkable EC₅₀ value for T. brucei parasites (0.026 μM ) combined with a very low cytotoxicity toward mammalian L6 cells (7.95 μM ). This promising low toxicity of compound 6 might be at least partially due to the fact that it does not interfere with human glutathione reductase.     

Synthesis of Cryptochiral (R,R)-2,3-Dideuterooxirane as Stereochemical Reference Compound and Chemical Correlation with D-(+)-Glyceraldehyde

Chirality plays a pivotal role in chemistry and biology, e.g., structure-specific targeting in drug development or the lock-and-key theory of enzyme interactions. Determining absolute configurations of chiral molecules is essential to understanding such mechanisms and to developing chemical processes involving chiral compounds. In particular, this becomes obvious in the understanding of chemical reaction networks in the context of the origins of life. A stereochemical reference compound that can be correlated with sugars, amino acids, etc. is of great interest. Here, we present the synthesis of enantiopure (R,R)-2,3-dideuterooxirane, of which the absolute configuration has been unambiguously determined by foil-induced Coulomb explosion imaging, and the correlation with the configuration of D-(+)-glyceraldehyde.     

Cloning and characterization of a novel NAD+‐dependent glyceraldehyde‐3‐phosphate dehydrogenase gene from Candida glycerinogenes and use of its promoter

A 3950 bp genomic fragment from Candida glycerinogenes, WL2002‐5, containing the CgGAP gene encoding a glyceraldehyde‐3‐phosphate dehydrogenase homologous to GAP genes in other yeasts using degenerate primers, was cloned and characterized with inverse PCR. Sequence analysis revealed a 1164 bp open reading frame encoding a putative peptide of 387 deduced amino acids, with a molecular mass of 36 kDa. The CgGAP protein consisted of an N‐terminal NAD⁺‐binding domain and a central catalytic domain. Six stress‐response elements were found in the upstream region of the CgGAP gene. The influence of CgGAP on glycolysis was investigated. Functional analysis revealed that Saccharomyces cerevisiae transformed with CgGAP was restored to the wild‐type phenotype when cultured in high‐osmolarity medium, suggesting that it is a functional GAP protein. Promoter studies in S. cerevisiae using the green fluorescent protein (gfp) gene as a reporter showed that the GAP promoter (P_CgGAP) is constitutively expressed in S. cerevisiae cells grown on glucose. Copyright © 2013 John Wiley & Sons, Ltd.     

Characterisation of a Recombinant NADP‐Dependent Glycerol Dehydrogenase from Gluconobacter oxydans and its Application in the Production of L‐Glyceraldehyde

The acetic acid bacterium Gluconobacter oxydans has a high potential for oxidoreductases with a variety of different catalytic abilities. One putative oxidoreductase gene codes for an enzyme with a high similarity to the NADP⁺‐dependent glycerol dehydrogenase (GlyDH) from Hypocrea jecorina. Due to this homology, the GlyDH (Gox1615) has been cloned, over‐expressed in Escherichia coli, purified and characterised. Gox1615 shows an apparent native molecular mass of 39 kDa, which corresponds well to the mass of 37.213 kDa calculated from the primary structure. From HPLC measurements, a monomeric structure can be deduced. Kinetic parameters and the dependence of the activity on temperature and pH were determined. The enzyme shows a broad substrate spectrum in the reduction of different aliphatic, branched and aromatic aldehydes. Additionally, the enzyme has been shown to oxidize a variety of different alcohols. The highest activities were observed for the conversion of D ‐glyceraldehyde in the reductive and L ‐arabitol in the oxidative direction. Since high enantioselectivities were observed for the reduction of glyceraldehyde, the kinetic resolution of glyceraldehyde was investigated and found to yield enantiopure L ‐glyceraldehyde on preparative scale.     

原位生物合成中甘油醛改性细菌纤维素的研究

以木醋杆菌为菌种,在椰子水培养体系中添加甘油醛原位生物合成改性细菌纤维素(Bacterial cellulose,BC)。发现未改性BC和改性BC均具有良好的三维网状结构和优良的吸水、持水性能。采用FTIR、XRD、TGA和电子万能试验机对产物进行了分析表征,并测试了产物的特性粘度。结果表明,与未改性BC相比,改性BC的化学结构无改变;随着体系中甘油醛添加量的增大,所合成的改性BC的结晶指数略降低,但是其纤维素Iα晶体的含量明显增加;而且改性BC显示出较好的热稳定性,当甘油醛添加量为10g/L时,改性BC的最大失重温度比未改性BC提高了约20℃。此外,培养基中甘油醛的添加可以制备出聚合度低、溶解性能更好、韧性更强的BC,这有利于BC在工业上更广泛的应用。     

The effect of ion pairs on the thermal stability of D-glyceraldehyde 3-phosphate dehydrogenase from the hyperthermophilic bacterium Thermotoga maritima

D-Glyceraldehyde 3-phosphate dehydrogenase from Thermotoga maritima(TmGAPDH) is intrinsically thermostable, exhibiting a thermaltransition beyond 105C. Neither the amino-acid compositionnor homology modelling, based on sequence alignment and known3-D structures of the enzyme from meso- and thermophiles, providean explanation of the anomalous stability. Recent X-ray datasuggest that an increased number of ion pairs is involved. Toprove this hypothesis, a number of charged residues contributingto ion pairs in TmGAPDH, but absent in the moderately thermophilicenzyme were altered. Elimination of peripheral ion pairs (E103-K104,E261-R266) was found to be ineffective. Altering a central chargecluster (R10-D47, E314, D*186) led to a drastic decrease incoenzyme binding. As a consequence, guanidine-dependent deactivationis shifted to significantly lower guanidinium chloride (GdmCl)concentrations without altering the denaturation/dissociationprofile of the wild type enzyme. Mutants in the S loop (R195D,R195D-D181K) lead to a biphasic profile in the GdmCl-dependentdenaturation transition and significant destabilization; atroom temperature no subunit dissociation could be observed.     

纳米TiO2-Pt修饰电极的制备、性能及应用

采用电化学合成法和电沉积法制备高活性钛基纳米TiO₂-Pt(Ti/nano-TiO₂-Pt)修饰电极,通过循环伏安法研究并比较了钛基纳米TiO₂膜电极、纯Pt电极、Ti/nano-TiO₂-Pt电极在H₂SO₄溶液中的电化学行为以及Ti/nano-TiO₂-Pt电极对Mn²⁺氧化为Mn³⁺的电催化性能.结果表明纳米TiO₂-Pt修饰电极对Mn²⁺的电氧化有高催化活性.Mn²⁺氧化峰电位为1.28 V（vs SCE）,比纯Pt电极负移0.12 V;析氧电位为1.40 V,比纯Pt电极高0.08 V.Ti/nano-TiO₂-Pt修饰电极催化性能优于纯Pt电极和纳米TiO₂膜电极,非均相电解氧化效率可达90%以上.电解得到的Mn³⁺可一步氧化甘油为甘油醛,收率为96%.     

Superoxide dismutases exhibit oxidase activity on aldehyde alcohols similar to alcohol oxidase from Paenibacillus sp. AIU 311

The relations between oxidase activity on aldehyde alcohols and superoxide dismutase (SOD) were investigated, since the amino terminal amino acid sequence of alcohol oxidase (AOD) from Paenibacillus sp. AIU 311, which was specific to aldehyde alcohols, exhibited high similarity to those of SODs containing manganese (Mn(2+)-SOD). Paenibacillus AOD had high SOD activity. The SODs containing manganese, iron, or copper and zinc also exhibited oxidase activities on aldehyde alcohols, and the relative values of oxidase activities on aldehyde alcohols to SOD activity of Mn(2+)-SOD were closer to those of Paenibacillus AOD compared with those of the other SODs. Thus, SODs had AOD activity on aldehyde alcohols as another enzyme activity, and the Paenibacillus AOD and Mn(2+)-SOD were classified into a similar group.     

Characterization of amino cross-linked soy protein hydrogels

ABSTRACT:  This study focused on amino cross-linking as means of forming soy protein hydrogels with modifiable properties. The efficiency of glyceraldehyde, a potential food-grade cross-linking agent, was compared to glutaraldehyde, a well-known dialdehyde. The influence of the concentration of these agents on the degree of cross-linking as well as macroscopic and supramolecular properties was studied. The effect of increasing the cross-linker concentration was mainly an increase in degree of cross-linking and gel storage modulus ( G ') and a decrease in gel swelling ratio and increase in gel deswelling ratio. However, the cross-linking influence was less pronounced in the case of glyceraldehyde. Glutaraldehyde displayed greater ability to form hydrogels with modifiable properties. Finally, electron micrographs suggested that cross-linking agent type had no impact on gel microstructure.