Coordination and Photoisomerization of Azobenzene-Amino Acid Schiff Base Copper(II) Complexes to Lysozyme

In this study, we exhibited an amino acid (arginine and threonine) derivative Schiff base copper(II) complexes incorporating an azobenzene moiety as a photoresponsive site and conjugated it to egg white lysozyme, a well-known protein, to change ligand conformation under binding to lysozyme. Among several spectroscopic investigations, ESR clearly showed that the nitrogen atom of the amino acid residue of lysozyme was bound to the paramagnetic copper(II) ion of the complex, and UV light irradiation confirmed photoisomerization of the azobenzene moiety of the ligand to cis-form. The binding mode was considered by means of spectroscopic as well as computational methods, whereas complete crystallographic verification was still a preliminary stage.

Chiral Recognition of Dansyl Derivatives with an Amino Acid-Based Molecular Micelle: A Molecular Dynamics Investigation

In this study, the chiral separation mechanisms of Dansyl amino acids, including Dansyl-Leucine (Dans-Leu), Dansyl-Norleucine (Dans-Nor), Dansyl-Tryptophan (Dans-Trp) and Dansyl-Phenylalanine (Dans-Phe) binding to poly-sodium N-undecanoyl-(L)-Leucylvalinate, poly (SULV), were investigated using molecular dynamics simulations. Micellar electrokinetic chromatography (MEKC) has previously shown that when separating the enantiomers of these aforementioned Dansyl amino acids, the L-enantiomers bind stronger to poly (SULV) than the D-enantiomers. This study aims to investigate the molecular interactions that govern chiral recognition in these systems using computational methods. This study reveals that the computationally-calculated binding free energy values for Dansyl enantiomers binding to poly (SULV) are in agreement with the enantiomeric order produced in experimental MEKC studies. The L-enantiomers of Dans-Leu, Dans-Nor, Dans-Trp, and Dans-Phe binding to their preferred binding pockets in poly (SULV) yielded binding free energy values of -21.8938, -22.1763, -21.3329 and -13.3349 kJ·mol-1, respectively. The D-enantiomers of Dans-Leu, Dans-Nor, Dans-Trp, and Dans-Phe binding to their preferred binding pockets in poly (SULV) yielded binding free energy values of -14.5811, -15.9457, -13.6408, and -12.0959 kJ·mol-1, respectively. Furthermore, hydrogen bonding analyses were used to investigate and elucidate the molecular interactions that govern chiral recognition in these molecular systems.

Rapid, accurate and serotype independent pipeline for in silico epitope mapping of SARS-CoV-2 antigens: a combined machine learning and Chou’s pseudo amino acid composition method

Here,a new integrated machine learning and Chou’s pseudo amino acid composition method has been proposed for in silico epitope mapping of severe acute respiratorysyndrome-like coronavirus antigens.For this,a training dataset including 266 linear B-cell epitopes,1,267 T-cell epitopes and 1,280 non-epitopes were prepared.The epitope sequences were then converted to numerical vectors using Chou’s pseudo amino acid composition method.The vectors were then introduced to the support vector machine,random forest,artificial neural network,and K-nearest neighbor algorithms for the classification process.The algorithm with the highest performance was selected for the epitope mapping procedure.Based on the obtained results,the random forest algorithm was the most accurate classifier with an accuracy of 0.934 followed by K-nearest neighbor,artificial neural network,and support vector machine respectively.Furthermore,the efficacies of predicted epitopes by the trained random forest algorithm were assessed through their antigenicity potential as well as affinity to human B cell receptor and MHC-I/II alleles using the VaxiJen score and molecular docking,respectively.It was also clear that the predicted epitopes especially the B-cell epitopes had high antigenicity potentials and good affinities to the protein targets.According to the results,the suggested method can be considered for developing specific epitope predictor software as well as an accelerator pipeline for designing serotype independent vaccine against the virus.

Characterization of Amino Acid Based Molecular Micelles with Molecular Modeling

The enantiomers of chiral drugs often have different potencies, toxicities, and biochemical properties. Therefore, the FDA and other worldwide regulatory agencies require manufactures to test and prove the enantiomeric purity of chiral drugs. Amino acid based molecular micelles (AABMM) have been used in chiral CE separations since the 1990’s because of their low environmental impact and because their properties can easily be tuned by changing the amino acids in the chiral surfactant head groups. Using molecular dynamics simulations to investigate the structures and properties of AABMM is part of an ongoing study focusing on investigating and elucidating the factors responsible for chiral recognition with AABMM. The results will be useful for the proper design and selection of more efficient chiral selectors. The micelles investigated contained approximately twenty covalently linked surfactant monomers. Each monomer was in turn composed of an undecyl hydrocarbon chain bound to a dipeptide headgroup containing of all combinations of L-Alanine, L-Valine, and L-Leucine. These materials are of interest because they are effective chiral selectors in capillary electrophoresis separations. Molecular dynamics simulation analyses were used to investigate how the sizes and positions of the headgroup amino acid R-groups affected the solvent accessible surface areas of each AABMM chiral center. In addition, headgroup dihedral angle analyses were used to investigate how amino acid R-group size and position affected the overall headgroup conformations. Finally, distance measurements were used to study the structural and conformational flexibilities of each AABMM headgroup. All analyses were performed in the context of a broader study focused on developing structure-based predictive tools to identify the factors responsible for a) self-assembly, b) function, c) higher ordered structure and d) molecular recognition of these amino acid based molecular micelles.

Synthesis, oxygenation and catalytic performance of manganese complex with p-aminomethyl benzoic acid Schiff base

The amino acid Schiff base complex (Sal-AMBA-Mn) was prepared with p-amino-methylbenzoic acid, salicylaldehyde and Mn(OAc)2·4H2O. Its structures was characterized with IR and UV spectra. Oxygenation mechanism of the complex in N, N-dimethylformamide solution was investigated. The results show that lower temperature is in favor of the oxygenation, and energy, enthalpy and entropy are -3.8 kJ/mol, -4.2 J/mol and -161.44 J/(mol·K), respectively. In the presence of the manganese complex, dehydroepiandrosterone acetate is effectively oxidized by molecular oxygen and the corresponding enone 7-ketodehydroepiandrosterone acetate is obtained. The yield is 62.1% when the oxidation is carried out under the reaction conditions of 60 ℃, 2 MPa of O2 pressure, C5H5N as a solvent and molar ratio of the substrate to the complex of 1:10.

Binol Based Chirality Conversion Reagents for Underivatized Amino Acids

Four binol based pyrrole carboxamide chiral receptors has been synthesized and effectively used as a Chirality Conversion Reagent (CCR) for underivatized amino acids. Three points of interactions take place for the conversion process. They are the reversible imine formation, the internal resonance assisted Hydrogen Bonding (RAHB) and the additional hydrogen bonds between the amino acids and the heterocylic moiety of the pendant groups. The conversion efficiency of all the receptors was found to be comparable with those of the receptors reported earlier.

The Synthesis of Some Novel N-[α-(Isoflavone-7-O-) Acetyl]Amino Acid Derivatives

A series of novel N-[α-(isoflavone-7-O-)acetyl] amino acid methyl esters were prepared from the efficient and regioselective alkylation of isoflavones with chloroacetyl amino acid derivatives under mild condition.

Effects of bamboo charcoal-based bio-fertilizer on wine bamboo sap yield and nutrient composition

To explore fertilization methods for wine bamboo cultivation in southwestern semi-arid areas of China, this study analyzed annual changes in sap yield and nutrient composition from May 2013 to March 2015 by using bamboo charcoal-based bio-fertilizer （ZT） and organic fertilizer treatments （CK）. The study also provided basic data for functional beverage preparation and for application of ZT. The results of the two experimental cycles revealed that under the ZT treatment, sap was available for collection from May, the beginning of the rainy season, to November, the beginning of the dry season. The period of abundance was July to October with the highest yield of sap of 3.18 L stalk-1 in September, 2014, still lower than the moso bamboo sap, which was likely due to the scale of sap production of monopodial bamboos being different from that of sympodial bamboos. In January, trace amounts of sap were still detected, suggesting that the effect of the treatment was significant. Moreover,in the dry season, soil water content and soil temperatures at 10-15 cm depths indicated that the fertilizer had the ability to maintain soil temperatures and moisture. In both fertilizer treatments, the correlation between the collected sap and environmental parameters was significant. In the ZT treatment for the entire 2 years, the effectual environ- mental factors were soil water at 10-15 cm, air tempera- tures, and wind speeds. The same determining factors were observed for the rainy season. In the CK treatments, the effectual environmental factors for the entire year and the rainy season were soil water at 0-5 cm and air moisture. The bamboo charcoal-based bio-fertilizer elevated the potassium, calcium, iron, manganese, copper, and total phosphorus content, simultaneously increasing the sap yield, protein and reducing sugar contents, and with a relative increase in sap pH. The wine bamboo sap con- tained 18 amino acids. Glutamic acid, alanine and proline were the most abundant. Compared to the controls, the treatment showed higher levels of all amino acids. Thus, the ZT treatment could be more beneficial to the development of root systems because the function of heat preservation and moisture retention prolong the sap collection period, increase sap yields, and elevate mineral element, conventional nutrients, and amino acid contents with evident fertilization effects and broader application prospects.

Synthesis and Characterization of Lanthanum Complexes with Amino Acid Schiff Base

Six new complexes of lanthanum with amino acid Schiff base ligands, A-F, were prepared in methanol-aqueous solution. The composition and properties of the title complexes were characterized by elemental analysis, molar conductance, infrared, electronic spectra, H-1 NMR, thermogravimetric and differential thermal analysis.

SYNTHESIS AND CHARACTERIZATION OF AMINO－ACID SCHIFF BASE AND ITS GERMANIUM COMPLEX

Condensation of eqqimolar quantities of salicylaldehyde and a-amino acid (glycine, alanine, valine, leucine, Phenylalanine, serine, cysteine) in absolute Methanol-KOH gives the amino acid Schiff base[1]. Its germanium tetrachloride adducts of the type GeCL. (sal=aa.k)2 have been prepared in absolute mothanol[2]and characterized by elemental analyses, conductance measurements, IR and 1H-NMR spectra, electronic spectra, cyclic voltammetry and thermal analyses. etc.

Synthesis, spectral, 3D molecular modeling and antibacterial studies of dibutyltin (IV) Schiff base complexes derived from substituted isatin and amino acids

New dibutyltin(IV) complexes of Schiff base derived from 5-chloroindoline-2,3-dione, indoline- 2,3-dione with amino acids (tryptophan, alanine and valine) were synthesized and characterized by elemental analysis, IR, electronic spectra, conductance measurements, and biological activity. The analytical data showed that the Schiff base ligand acts as bidentate towards metal ions via the azomethine nitrogen and carboxylate oxygen by a stoichiometric reaction of M:L (1:2) to form metal complexes. NMR (1H, 13C and 119Sn) spectral data of the ligands and metal complex agree with proposed structures. The conductivity values between 14 - 27 ohm-1cm2mol-1 in DMF imply the presence of non-electrolyte species. 3D molecular modeling and analysis of bond lengths and bond angles have also been conducted for a representative compound, [Bu2Sn(L2)2], to substantiate the proposed structures. Antibacterial results indicate that the metal complexes are more active than the free ligands.

Construction of Free Amino Acids Composition Data Base for Food

Significant amounts of free amino acids exist in commercially sold vegetables and fruits. Despite of the fact, only a little information is available about the free amino acid contents in foods. To utilize information of free amino acids in food, we have carried out the experiments to quantitate the free amino acids by derivatized with NBD-F （4-fluoro-7-nitrobenzofurazan） and analyzed on reversed-phase UHPLC （ultra-high pressure liquid chromatography） equipped with ultraviolet visible detector. Almost all of food extracts contained free amino acids including GABA （T-amino butyrate）. Contents of free amino acids vary considerably depending upon vegetables and fruits. Principal free amino acids found in vegetables and fruits were asparagine, glutamine, arginine and GABA, which are involved in important metabolic pathways in human. About 140 species of vegetables and fruits were subjected for the data base. All of the plants and fruits we examined exhibit significant amount of free amino acids, those are clearly distinct from data bases obtained after acid hydrolysis treated food samples. Since glutamate and GABA act as excitatory and inhibitory neurotransmitters in CNS, respectively; free amino acids in vegetables and fruits that we eat daily, should be an important source for the cellular metabolic activities.

氨基-磷酸改性铁基空心玻璃微珠催化剂用于天然气湿法氧化脱硫

目的为了避免常规天然气湿法氧化脱硫工艺中硫磺沉积引发的设备堵塞问题,开发了一种氨基-磷酸双官能团改性的铁基空心玻璃微珠(HGB)催化剂,用于脱硫-再生分步进行方案中脱硫富液的非均相催化氧化再生。方法采用红外光谱表征催化剂的结构。通过静态脱硫实验研究了硅烷偶联剂KH-550的配比、焙烧温度、FeCl 3投加量等因素对脱硫剂再生及脱硫效果的影响,并考查了催化剂的重复使用性能。结果氨基-磷酸改性铁基HGB催化剂可实现脱硫富液的有效再生,且能在酸性的脱硫液中保持稳定,在温度为300℃下焙烧6 h、HGB与KH-550质量比为1∶8、HGB与FeCl_(3)·6H_(2)O质量比为1∶5的条件下制备的铁基HGB催化剂具有最佳催化性能,对脱硫液重复再生3次后,脱硫液性能基本保持稳定。红外光谱分析结果表明催化剂结构保持完好。结论氨基-磷酸改性铁基HGB催化剂在天然气湿法氧化脱硫领域中对脱硫富液的再生具有较好的效果,可为目前脱硫富液的再生提供新的选择。

Synthesis and Structural Characterization of Some Diorganotin Complexes of N-(3,5-Dibromosalicylidene)-α-amino Acid and their Diphenyltin Dichloride Adducts

The title complexes, R′2Sn(3,5-Br2-2-OC6H2CH=NCHRCOO), and their diphenyltindichloride adduct, R′2Sn(3,5-Br2-2-OC6H2CH=NCHRCOO)?SnPh2Cl2, were synthesized and char-acterized by elemental analysis, IR, H and C NMR and X-ray single crystal diffraction. The 1 13structural features of the compounds were described.

Prediction of Protein-Protein Interactions by a Novel Model Based on Domain Information

Domain-based protein-protein interactions( PPIs) is a problem that has drawn the attentions of many researchers in recent years and it has been studied using lots of computational approaches from many different perspectives. Existing domain-based methods to predict PPIs typically infer domain interactions from known interacting sets of proteins. However,these methods are costly and complex to implement. In this paper, a simple and effective prediction model is proposed. In this model,an improved multiinstance learning( MIL) algorithm( MilCaA) is designed that doesn't need to take the domain interactions into consideration to construct MIL bags. Then, the pseudo-amino acid composition( PseAAC) transformation method is used to encode the instances in a multi-instance bag and the principal components analysis( PCA) is also used to reduce the feature dimension. Finally, several traditional machine learning and MIL methods are used to verify the proposed model. Experimental results demonstrate that MilCaA performs better than state-of-the-art techniques including the traditional machine learning methods which are widely used in PPIs prediction.

NMR-based metabolomics pro!le analysis in understanding metabolic variations of Bra LTP1-overexpressing Brassica napus

BraLTP1 is an important member of lipid transfer protein family in Brassica napus.The aim of current study was to detect, classify and follow variations in metabolite profiling of B. napus with overexpression of BraLTP1. In this study, metabolic change in leaves of BraLTP1-overexpressing B. napus plants (BraLTP1-22) and negative control (BraLTP1-22N) was investigated using nuclear magnetic resonance (NMR). Statistical strategy of principle component analysis (PCA) was performed to identify related difference metabolites. PCA score plots indicated not only high reproducibility of various treatments, but also significant difference of metabolite levels between different treatments. PCA loading plots indicated main responsible metabolites and a total of 50 metabolites were quantitatively determined. A wide range of metabolites were detected due to BraLTP1 overexpression,including biosynthesis and metabolism of sugars, amino acids, ammoniums compounds and organic acids. Furthermore, concentrations of 17 amino acids were determined for other set of samples by amino acids component analysis assay. The link between metabolite variations and phenotype were also discussed in BraLTP1-overexpressing B. napus.This work will help to gain insight into BraLTP1 function in B. napus in metabolism.

Schiff-base Amino Alcohol-zinc Complex for Enantioselective Addition of Phenylacetylene to Aromatic Ketones

A complete study of the asymmetric addition of phenylacetylene to ketones catalyzed by Schiff-base amino alcohol-Zn complex is reported in this article. The Schiff-base amino alcohols were easily prepared from amino acids in three steps. When the amount of ligand was 1%（molar fraction）, an e.e. value up to 94% was obtained. A series of practical chiral ligands were applied in the enantioselective addition of phenylacetylene to ketones without adding another stronger Lewis acid except zinc.

5-硝基水杨醛氨基酸Schiff-bases铜配合物与DNA相互作用的研究

用电子光谱、荧光淬灭光谱和循环伏安的方法,研究了(苯丙氨酸缩5-硝基水杨醛)铜(1)和(组氨酸缩5-硝基水杨醛)铜(2)与 DNA 的作用.结果表明,配合物均以插入模式与 DNA 作用;配合物与 DNA 作用强弱为:配合物(2)>配合物(1).

A Zn(Ⅱ) Coordination Polymer Based on a Flexible Symmetric Multicarboxylate Ligand

A novel coordination polymer, namely [Zn2（CAPA）（DMA）（H2O）]2n·n（H2O）（1,H4CAPA = 5-（bis（4-carboxybenzyl） amino） isophthalic acid, DMA = N,N-dimethylacetamide） has been synthesized through a solvothermal method and characterized by single-crystal X-ray diffraction, elemental analysis, infrared spectra, and thermogravimetric analyses. The crystal structure is of monoclinic, space group P21/n with a = 8.0585（5）, b = 18.9733（10）, c = 20.2044（14） A^°3, β = 101.144（7）°, V = 3030.9（3） ？~3, C56H54Zn4N4O21, Mr = 1378.58, Z = 2）. The compound forms a three-dimensional（3D） supramolecular framework by linking adjacent layers via hydrogen bonds and π···π interactions. It is interesting that the crystal structure is much related to the flexibility and configuration of the ligand. In addition, the thermal stability and luminescence properties for the compound have also been investigated.

Enantiomeric Separation of Amino Alcohols by Ion-pair Chromatography

Enantiomers of four amino alcohols were resolved by ion-pair chromatography with (+)-10-camphorsulphonic acid as chiral counter ion. Studies of the influence of the mobile phase composition, the solute structure and the mobile phase flow-rate on separation are presented. Under the optimized conditions enantiomeric propanolol, norephedrine, metropolol and salbutamol were separated using dichloromethane-1-pentanol (97:3 v/v) as mobile phase on Lichrospher-100-DIOL column.