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Hypochlorous acid (HOCl) plays a crucial role in many physiological processes and is widely used as bleach, deodorant and fungicide. In this work, we designed an amphiphilic hydrazone fluorescent molecule THG-1 containing hydrophilic sugar units and hydrophobic tetraphenylethylene unit for ratiometric detection of HOCl with high sensitivity and excellent selectivity based on HOCl-triggered hydrolyzation reaction and aggregation-induced emission (AIE) effect. The detection mechanism was verified by liquid chromatograph mass spectrometry experiments and scanning electron microscope (SEM) tests. Contrast experiments revealed that the numbers of lactose unit and hydrazone linker were essential for assembly of THG-1 and detection of HOCl. In addition, THG-1 was successfully used for imaging of exogenous and endogenous HOCl in living cells.

The synthesis of O-, C-, and N-glycoconjugates has continuously been an attractive research subject due to the growing biological importance of various glycoconjugates. In recent years, by careful changing the glycosylation reaction conditions, especially the amount of activators and the preactivation temperature, (p-Tol)2SO/Tf2O preactivition strategy was developed as a general method for the synthesis of various O-, C-, and N-glycoconjugates, including related biological active glycoconjugates, such as nucleosides and antigen Lewisa etc. High yields and excellent stereoselectivities were obtained even without the anchimeric assistance at the adjacent position of anomeric carbon. In this review, we predominantly make a review on the progress of the (p-Tol)2SO/Tf2O preactivition strategy from O-, C-sialylation to general O-, N-glycosylation.

Imaging-based total bacterial count and type identification of bacteria play crucial roles in clinical diagnostics, public health, biological and medical science, and environmental protection. Herein, we designed and synthesized a series of tetraphenylethenes (TPEs) functionalized with one or two aldehyde, carboxylic acid, and quaternary ammonium groups, which were successfully used as fluorescent materials for rapid and efficient staining of eight kinds of representative bacterial species, including pathogenic bacteria Vibrio cholera, Klebsiella pneumoniae, and Listeria monocytogenes and potential bioterrorism agent Yersinia pestis. By comparing the fluorescence intensity changes of the aggregation-induced-emission (AIE) materials before and after bacteria incubation, the sensing mechanisms (electrostatic versus hydrophobic interactions) were simply discussed. Moreover, the designed AIE materials were successfully used as an efficient artificial tongue for bacteria discrimination, and all of the bacteria tested were identified via linear discriminant analysis. Our current work provided a general method for simultaneous broad-spectrum bacterial imaging and species discrimination, which is helpful for bacteria surveillance in many fields.

Based on a preactivation strategy using ( p -Tol) 2 SO/Tf 2 O, a new O -fucosylation method with thioglycoside as donor under mild conditions was reported. High yields and excellent α-stereoselectivities of the fucosylation were obtained with secondary sugar alcohol as acceptors. Moreover, the novel fucosylation strategy was successfully applied to the synthesis of an important Lewis blood group antigen Lewis a , which was obtained in nine linear steps with 27% overall yield.

Water-soluble ratiometric AIE-active fluorescent organic nanoparticles 2OA-FON for the specific sensing of cysteine over other biothiols are reported. The obtained amphiphilic probe included olefin aldehyde as recognizing unit, tetraphenylethylene as fluorescence reporter and lactose moiety as a hydrophilic group. This work provides a general design strategy based on the introduction of a sugar moiety into a hydrophobic AIEgen to develop ratiometric water-soluble fluorescent organic nanoparticles.

Ginsenoside is a large family of triterpenoid saponins from Panax ginseng, which possesses various important biological functions. Due to the very similar structures of these complex glycoconjugates, it is crucial to develop a powerful analytic method to identify ginsenosides qualitatively or quantitatively. We herein report an eight-channel fluorescent sensor array as artificial tongue to achieve the discriminative sensing of ginsenosides. The fluorescent cross-responsive array was constructed by four boronlectins bearing flexible boronic acid moieties (FBAs) with multiple reactive sites and two linear poly(phenylene-ethynylene) (PPEs). An "on-off-on" response pattern was afforded on the basis of superquenching of fluorescent indicator PPEs and an analyte-induced allosteric indicator displacement (AID) process. Most importantly, it was found that the canonical distribution of ginsenoside data points analyzed by linear discriminant analysis (LDA) was highly correlated with the inherent molecular structures of the analytes, and the absence of overlaps among the five point groups reflected the effectiveness of the sensor array in the discrimination process. Almost all of the unknown ginsenoside samples at different concentrations were correctly identified on the basis of the established mathematical model. Our current work provided a general and constructive method to improve the quality assessment and control of ginseng and its extracts, which are useful and helpful for further discriminating other complex glycoconjugate families.

Four-channel fluorescence assay toward six monosaccharides was achieved by employing two novel pyrene-functionalized boronlectins with flexible diboronic acid as receptors. The effects of pH values and aging time on the sensor properties were thoroughly evaluated by UV-vis, fluorescence spectroscopy and dynamic light scattering. We find that the fluorescence relative ratios were highly correlated with analyte concentrations at μM level. The flexibility of the receptors was perceived as an indispensable factor to produce diverse fluorescence signals toward different monosaccharides. Most importantly, integration of four fluorescence channels derived from the two sensors enables an excellent discrimination for all tested monosaccharides at a certain concentration or a concentration range via linear discriminant analysis (LDA). It is proposed that the multiple flexible linkers in the boronlectins could increase their self-adaptive capacity for different analytes, and facilitate the formation of stable boronlectin-sugar aggregate assemblies. In addition, practical sensing of glucose in the simulative blood and urine was illustrated to be feasible in the presence of interferences at physiological concentrations.

N,N-Di-2-picolylamine (DPA)-derived diboronic acid receptors (NHBAs) with a flexible linker were designed and synthesized in this study, and two-component sensing ensembles based on cationic NHBAs and an anionic fluorescent indicator 8-hydroxypyrene-1,3,6-trisulfonic acid trisodium salt (HPTS) were successfully developed for both monosaccharides and disaccharides sensing. The dibranched ortho-substituted receptor NHoBA exhibited unexpected selectivity towards lactose among five disaccharides used. The discrimination of five disaccharides and six monosaccharides was finally achieved by the integrated sensor array through linear discriminant analysis (LDA).

Based on a preactivation strategy using the (p-Tol)2SO/Tf2O system, a series of nucleosides were synthesized by coupling various thioglycosides with pyrimidines and purines under mild conditions. High yields and excellent β-stereoselectivities were obtained with either armed or disarmed N-glycosylation donors by tuning the amount of (p-Tol)2SO additive.

YhdE is a Maf (multicopy associated filamentation) proteins from Escherichia coli which exhibits pyrophosphatase activity towards selected nucleotides, although its catalytic mechanism remains unclear. Herein we used a novel fluorescence probe (4-isoACBA–Zn(II) complex) to characterize the enzymatic properties of YhdE and its mutant, establishing a new method for assaying pyrophosphatase catalytic function. Our results reveal for the first time that the new fluorescence sensor confers high sensitivity and specificity and pyrophosphate (PPi) is the direct catalytic product of YhdE. Crystal structures of a mutant in the active-site loop (YhdE_E33A) show conformational flexibility implicated in the catalytic mechanism of YhdE. ITC experiments and computational docking further reveal that Asp70 and substrate dTTP coordinate Mn2+. Quantum mechanics calculations indicate that YhdE hydrolysis appears to follow a stepwise pathway in which a water molecule first attacks the α-phosphorus atom in the substrate, followed by the release of PPi from the pentavalent intermediate.

A dialdehyde–diboronate-functionalized tetraphenylethene (TPE-DABF) was reported as a H2O2-specific AIE luminogen. TPE-DABF, bearing multiple reductive units (aldehyde, boronate and fructose) in one molecule, afforded an excellent H2O2 selectivity over other ROS in biological buffer, and can be used for sensitive detection of glucose under neutral conditions.

Sweet as sugar: Sialyl sulfoxide protected by N-acetyl-5-N,4-O-oxazolidinone was readily prepared, and its coupling to various sugar acceptors was investigated. When the reaction was promoted by Tf(2)O/(Tol)(2)SO, efficient and highly α-selective sialylation yielded α(2,6), α(2,3), and α(2,4) glycosidic linkages between sialic acid and glucose/glacotose.

Anionic conjugated polymer (PFP-SO 3 ) was assembled with a novel enzymatic substrate 6-O-modified PNP-,B-galactoside (1) for sensitive multiplex enzyme detections. The PFP-SO 3 - /1/ lipase/β-galactosidase system has two chemical input signals which are Input 1 (lipase) and Input 2 (β-galactosidase), and output optical signals such as fluorescence emission at 416 nm or 450 nm. Four types of logic gates, including YES, INH, NAND and AND, were successfully constructed and utilized for multiplex detections of lipase and β-galactosidase in one tube.

Ganglioside GM3 [α-Neu5Ac-(2,3)-β-Gal-(1,4)-β-Glc-(1,1)-Cer; 1] is considered as an important tumor-associated carbohydrate antigen, which can be used in the development of tumor vaccine. In this study, a facile and convergent synthetic strategy for GM3 was developed, and the preparation of three building blocks started from the most readily available compounds sialic acid, lactose, and L-serine. Ceramide aglycon 9 was constructed from L-serine in 13 steps with 6 % overall yield, and lactosyl trichloroacetimidate 14 was synthesized from lactose in 7 steps with 25 % yield. With novel N-acetyl-5-N,4-O-oxazolidinone protected p-toluenethiosialoside 15 as donor, which was developed by our group, the sialylation of benzoyl-protected lactosyl ceramide diol 23 was successfully accomplished in 54 % yield. Our strategy here provides a shorter linear total synthesis of GM3 in five steps and with 26 % overall yield. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

The activity of enzymes to form a peptide bond in organic solvent was greatly influenced by observed pH and water content. The precursors of two sweeteners, P-Asp-Xaa-OR (P = Z or For, Xaa-OR = Phe-OMe or Ala-OcHex), were synthesized by enzyme, and the reaction conditions were studied systematically. Z-Asp-OH was coupled with H-Phe-OMe or H-Ala-OcHex by thermolysin in tert-amyl alcohol. The best coupling results were obtained when the optimized observed pH was 8 or 9, and the water content was about 6% (V/V). The protecting group Z is better than For under the reaction conditions and H-Phe-OMe is a better nucleophile than H-Ala-OcHex. The expected optically pure peptides were obtained when the racemic amino acids were used as amino components in the starting materials. The physical constants of P-Asp-Xaa-OR synthesized by thermolysin are identical with those of peptides synthesized by chemical method.

A series of N -protected amino acid-estradiol derivative conjugates have been synthesized by coupling of 17β-aminoestra-1,3,5 (10)-trien-3-ol ( 1 ) or 17β-hydrazonoestra-1,3,5 (10)-trien-3-ol ( 2 ) with different amino acids via the catalysis of subtilisin Carlsberg in organic solvent. Various factors, including the structure of amino acid residue, different N -protecting groups of amino acids, different esters of carboxyl group and water content of the reaction media that influence the efficiency of enzymatic reactions were systematically studied. In vitro biological activity studies revealed that the binding interactions between estradiol derivative conjugates and estrogen receptor can be affected by the properties of the conjugated amino acid, but the effects of the change in binding properties did not result in changes in biological activities in both MCF-7 and HeLa cell lines.

N-succinimidyloxycarbonylmethyl tris(2,4,6-trimethoxyphenyl) phosphonium bromide (TMPP-Ac-OSu) reacts rapidly, mildly, and specifically with the N-terminals of proteins and peptides. Thus, it can be developed as an ideal isotope-coded tag to be used in quantitative proteomics. Here, we present a strategy for light and heavy TMPP-based quantitative proteomic analysis, in which peptides in a mixture can be quantified using an on-tip TMPP derivatization approach. To demonstrate the accuracy of this strategy, light and heavy TMPP-labeled peptides were combined at different ratios and subsequently analyzed by LC-MS/MS. The MS spectra and scatter plots show that peptide and protein ratios were both consistent with the mixed ratios. We observed a linear correlation between protein ratios and the predicted ratios. In comparison with SILAC method, the TMPP labeling method produced similarly accurate quantitative results with low CVs. In conclusion, our results suggest that this isotope-coded TMPP method achieved accurate quantification and compatibility with IEF-based separation. With the inherent advantages of TMPP derivatization, we believe that it holds great promise for future applications in quantitative proteomics analysis.

Some oligopeptide derivatives were successfully synthesized in 56–88% yield by α-chymotrypsin in AOT-Brij30/n-heptane mixed reverse micelles. The reaction conditions such as W0 value, reaction time and the concentration of enzyme in the water pool were studied with ZTyrGlyGlyOEt as model peptide.

Twenty-one alkyl halides were examined in detail for their heavy atom effect in β-cyclodextrin induced room temperature phosphorescence (β-CD-RTP) with five polycyclic aromatic as mode compounds. The following conclusions were drawn from the experimental results. (1) The heavy atom enhancement effect (HAEE) of halogens in halide alkane are increased in the trend of Br > Cl ⪢ I. (2) Among the bromoalkanes examined, dibromoalkanes have the strongest HAEE, next the monobromoalkanes. For tri- and tetrabromoalkanes, very weak HAEE was observed. (3) A new heavy atom pertuber, t -butyl chloride, was found to have excellent ability of inducing RTP of polycyclic aromatic compounds. (4) The phosphorescence decay characteristics of the phosphorescent molecules, τ p , had been measured in the presence of halide alkanes and used to explain the luminescence mechanism of CD-RTP.

Some oligopeptide derivatives were successfully synthesized in 56–88% yield by α-chymotrypsin in AOT-Brij30/n-heptane mixed reverse micelles. The reaction conditions such as W0 value, reaction time and the concentration of enzyme in the water pool were studied with ZTyrGlyGlyOEt as model peptide.

Amino acid-estradiol derivatives were synthesized via protease-catalyzed condensation for the first time and the optimum conditions were studied systematically.

Peptidyl steroids are compounds in which amino acids or peptides are coupled with steroids by amide or ester bonds. Cholyl glycine and cholyl taurine are such analogs found in humans. Previously, we synthesized a new series of amino acid and peptide derivatives of estradiol using different coupling reagents, and studied their binding affinities [1]. Recently, significant progress has been made in the field of enzymatic peptide synthesis [2]. We synthesized a series of peptide derivatives such as Nprotected Leu-enkephalin in organic solvents using several peptidyl proteases [3]. The advantages of enzymatic synthesis include mild reaction conditions, no racemation, minimal side-chain protection, and high regioand stereoselectivity. In the current study, we report the successful synthesis of the N-protected amino acid-estrone derivatives using subtilisin Carlsberg as the catalyst in organic solvent for the first time. The influences of different protecting groups and esters in the carboxyl component on the enzymatic reaction were compared.

Enzymatic catalyzed reactions in organic solvents with a small amount of water content possess many advantages, such as great stability of enzymes in organic solvents etc.. We focused our attention on the influence of pH and water content on enzymatic peptide synthesis in organic media. N-P-L-Asp-XaaOR (P=Z or For, XaaOR=L-PheOMe or LAlaOcHex, cHex=cyclohexyl), the precursors of aspartame [1] and a new sweetener(L-AspL-AlaOcHex) [2,3], and N-Z-L-TyrGlyGlyOEt, a fragment of Leu-enkephaline as model peptides were synthesized by enzymes in organic solvents [4]. All the peptides were identified by MS, elemental analysis and optical rotation and they were identical with those peptides synthesized by chemical method.