Mechano-fluorochromic Pt-II Luminogen and Its Cysteine Recognition

A new triphenylamine-based organometallic Pt-II luminogen (1) and its analogous organic compound (2) are reported. The molecules are decorated with aldehyde functionality to improve their photophysical properties by utilising donor-acceptor interactions. The single crystal X-ray structure analysis of PtII analogue 1 revealed that the neighbouring molecules were loosely organised by weak intermolecular C-H center dot center dot center dot pi interactions. Because of the twisted nature of the triphenylamine backbone the compounds showed aggregation-induced emission enhancement in THF/water mixture. Due to their loose crystal packing, upon application of external stimuli these luminogens exhibited mechano-fluorochromic behaviour. The crystalline forms of the compounds displayed a more superior emission efficiency than the grinded samples. Moreover, the compounds showed crystallization-induced emission enhancement (CIEE) and exhibited chemodosimetric response towards cysteine under physiological condition.

Molecular mechanism of sulfated carbohydrate recognition: structural and biochemical studies of the cysteine-rich domain of mannose receptor

Mannose receptor (MR) is widely expressed on macrophages, immature dendritic cells, and a variety of epithelial and endothelial cells. It is a 180 kD type I transmembrane receptor whose extracellular region consists of three parts: the amino-terminal cysteine-rich domain (Cys-MR); a fibronectin type II-like domain; and a series of eight tandem C-type lectin carbohydrate recognition domains (CRDs). Two portions of MR have distinct carbohydrate recognition properties: Cys-MR recognizes sulfated carbohydrates and the tandem CRD region binds terminal mannose, fucose, and N-acetyl-glucosamine (GlcNAc). The dual carbohydrate binding specificity allows MR to interact with sulfated and nonsulfated polysaccharide chains, and thereby facilitating the involvement of MR in immunological and physiological processes. The immunological functions of MR include antigen capturing (through binding non-sulfated carbohydrates) and antigen targeting (through binding sulfated carbohydrates), and the physiological roles include rapid clearance of circulatory luteinizing hormone (LH), which bears polysaccharide chains terminating with sulfated and non-sulfated carbohydrates.

We have crystallized and determined the X-ray structures of unliganded Cys-MR (2.0 Å) and Cys-MR complexed with different ligands, including Hepes (1.7 Å), 4SO_4-N-Acetylgalactosamine (4SO_4-GalNAc; 2.2 Å), 3SO_4-Lewis^x (2.2 Å), 3S04-Lewis^a (1.9 Å), and 6SO_4-GalNAc (2.5 Å). The overall structure of Cys-MR consists of 12 anti-parallel β-strands arranged in three lobes with approximate three fold internal symmetry. The structure contains three disulfide bonds, formed by the six cysteines in the Cys-MR sequence. The ligand-binding site is located in a neutral pocket within the third lobe, in which the sulfate group of ligand is buried. Our results show that optimal binding is achieved by a carbohydrate ligand with a sulfate group that anchors the ligand by forming numerous hydrogen bonds and a sugar ring that makes ring-stacking interactions with Trpll7 of CysMR. Using a fluorescence-based assay, we characterized the binding affinities between CysMR and its ligands, and rationalized the derived affinities based upon the crystal structures. These studies reveal the mechanism of sulfated carbohydrate recognition by Cys-MR and facilitate our understanding of the role of Cys-MR in MR recognition of its ligands.

Purification and cloning of cysteine-rich proteins from Trimeresurus jerdonii and Naja atra venoms

Three 26 kDa proteins, named as TJ-CRVP, NA-CRVP1 and NA-CRVP2, were isolated from the venoms of Trimeresurus jerdonii and Naja atra, respectively. The N-terminal sequences of TJ-CRVP and NA-CRVPs were determined. These components were devoid of the enzymatic activities tested, such as phospholipase A(2), arginine esterase, proteolysis, L-amino acid oxidase, 5' nucleotidase, acetylcholinesterase. Furthermore, these three components did not have the following biological activities: coagulant and anticoagulant activities, lethal activity, myotoxicity, hemorrhagic activity, platelet aggregation and platelet aggregation-inhibiting activities. These proteins are named as cysteine-rich venom protein (CRVP) because their sequences showed high level of similarity with mammalian cysteine-rich secretory protein (CRISP) family. Recently, some CRISP-like proteins were also isolated from several different snake venoms, including Agkistrodon blomhoffi, Trimeresurus flavoviridis, Lanticauda semifascita and king cobra. We presumed that CRVP might be a common component in snake venoms. Of particular interest, phylogenetic analysis and sequence alignment showed that NA-CRVP1 and ophanin, both from elapid snakes, share higher similarity with CRVPs from Viperidae snakes. (C) 2003 Elsevier Ltd. All rights reserved.

Identification of an additional two-cysteine containing type I interferon in rainbow trout Oncorhynchus mykiss provides evidence of a major gene duplication event within this gene family in teleosts

Multiple type I interferons (IFNs) have recently been identified in salmonids, containing two or four conserved cysteines. In this work, a novel two-cysteine containing (2C) IFN gene was identified in rainbow trout. This novel trout IFN gene (termed IFN5) formed a phylogenetic group that is distinct from the other three salmonid IFN groups sequenced to date and had a close evolutionary relationship with IFNs from advanced fish species. Our data demonstrate that two subgroups are apparent within each of the 2C and 4C type I IFNs, an evolutionary outcome possibly due to two rounds of genome duplication events that have occurred within teleosts. We have examined gene expression of the trout 2C type I IFN in cultured cells following stimulation with lipopolysaccharide, phytohaemagglutinin, polyI:C or recombinant IFN, or after transfection with polyI:C. The kinetics of gene expression was also studied after viral infection. Analysis of the regulatory elements in the IFN promoter region predicted several binding sites for key transcription factors that potentially play an important role in mediating IFN5 gene expression.

Identification and characterization of a cathepsin L-like cysteine protease from Taenia solium metacestode

Taenia solium metacestode, a larval pork tapeworm, is a causative agent of neurocysticercosis, one of the most common parasitic diseases in the human central nervous system. In this study, we identified a cDNA encoding for a cathepsin L-like cysteine protease from the T solium metacestode (TsCL-1) and characterized the biochemical properties of the recombinant enzyme. The cloned cDNA of 1216 bp encoded 339 amino acids with an approximate molecular weight of 37.6 kDa which containing a typical signal peptide sequence (17 amino acids), a pro-domain (106 amino acids), and a mature domain (216 amino acids). Sequence alignments of TsCL-1 showed low sequence similarity of 27.3-44.6 to cathepsin L-like cysteine proteases from other helminth parasites, but the similarity was increased to 35.9-55.0 when compared to mature domains. The bacterially expressed recombinant protein (rTsCL-1) did not show enzyme activity; however, the rTsCL-1 expressed in Pichia pastoris showed typical biochemical characteristics of cysteine proteases. It degraded human immunoglobulin G (IgG) and bovine serum albumin (BSA), but not collagen. Western blot analysis of the rTsCL-1 showed antigenicity against the sera from patients with cysticercosis, sparganosis or fascioliasis, but weak or no antigenicity against the sera from patients with paragonimiasis or clonorchiasis. (c) 2006 Published by Elsevier B.V.

A study of low-energy ion induced radiolysis of thiol-containing amino acid cysteine in the solid and aqueous solution states

The radiolysis of cysteine under plasma discharge and irradiation of low-energy Ion beam was investigated. The damage of cysteine in aqueous solution under discharge was assessed via the acid ninhydrin reagent and the yield of cystine produced from the reaction was analyzed by FTIR In addition, the generation of hydrogen sulfide was also identified The destruction of solid cysteine under low-energy ion beam irradiation was estimated via monitoring IR bands of different functional groups (-SH, -NH3, -COO-) of cysteine. and the production of cystine from ion-irradiated solid cysteine after dissolution in water was also verified These results may help us to understand the inactivation of sulphydryl enzymes under direct and indirect interaction with the low-energy ion irradiation (C) 2010 Elsevier B V All rights reserved.

Formation of reversible shell cross-linked micelles from the biodegradable amphiphilic diblock copolymer poly(L-cysteine)-block-poly(L-lactide)

A novel biodegradable diblock copolymer, poly(L-cysteine)-b-Poly(L-lactide) (PLC-b-PLLA), was synthesized by ring-opening polymerization (ROP) of N-carboxyanhydride of beta-benzyloxycarbonyl-L-Cysteine (ZLC-NCA) with amino-terminated Poly(L-lactide) (NH2-PLLA) as a macroinitiator in a convenient way. The diblock copolymer and its precursor were characterized by H-1 NMR, Fourier transform infrared (FT-IR), gel permeation chromatography (GPC), and X-ray photoelectron spectroscopy (XPS) measurements. The length of each block polymer could be tailored by molecular design and the ratios of feeding monomers.

Sensitive detection of cysteine based on fluorescent silver clusters

In this work,we report the application of novel, water-soluble fluorescent Ag clusters in fluorescent sensors for detecting cysteine, an important biological analyte. The fluorescence of poly(methacrylic acid) (PMAA)templated Ag clusters was found to be quenched effectively by cysteine, but not when the other alpha-amino acids were present. By virtue of the specific response, a new, simple, and sensitive fluorescent method for detecting cysteine has been developed based on Ag clusters. The present assay allows for the selective determination of cysteine in the range of 2.5 x 10(-8) to 6.0 x 10(-6) M with a detection limit of 20 nM at a signal-to-noise ratio of 3. Based on the absorption and fluorescence studies, we suggested that cysteine quenched the emission by the thiol-adsorption-accelerated oxidation of the emissive Ag clusters. The present study shows a promising step toward the application of silver clusters, a new class of attractive fluorescence probes.

Fluorescent conjugated polymer-stabilized gold nanoparticles for sensitive and selective detection of cysteine

We report a new fluorescent detection method for cysteine based on one-step prepared fluorescent conjugated polymer-stabilized gold nanoparticles. The as-prepared fluorescent conjugated polymer-stabilized gold nanoparticles fluoresce weakly due to the fluorescence resonance energy transfer between the fluorophore and the gold nanoparticles. Upon the addition of cysteine, a thiol-containing amino acid, the fluorescence of the colloidal solution increases significantly, indicating that cysteine can modulate the energy transfer between fluorophore and gold. This phenomenon then allows for sensitive detection of cysteine with a limit of detection (LOD) of 25 nM. The linear range of determination of cysteine is from 5 x 10(-8) to 4 x 10(-6) M. None of the other amino acids found in proteins interferes with the determination. Moreover, due to the excellent protecting ability of the fluorescent conjugated polymers, the synthesis of metal nanoparticles and modifying with fluorophores can be accomplished within one step, which makes our method much simpler than conventional methods. We also expect that it will be possible to detect other biologically important analytes based on the fluorescent conjugated polymer-stabilized metal nanoparticles.

Electrochemiluminescent determination of L-cysteine with a flow-injection analysis system

A flow-injection electrochemiluminescent method for L-cysteine determination has been developed based on its enhancement of the electrochemiluminecence of luminol at a glassy carbon electrode. This method is simple and sensitive for cysteine determination. Under the selected experimental parameters, the linear range for cysteine concentration was 1.0 x 10(-6) - 5.0 x 10(-5) mol/l, and the detection limit was 0.67 mumol/l (SIN = 3). The relative standard deviation for 11 measurements of 1.0 x 10(-5) mol/l cysteine was 4.5%. The proposed method has been applied to. the detection of cysteine in pharmaceutical injections with satisfactory results.