Pseudopolyanions Based on Poly(NIPAAM-co-beta-Cyclodextrin Methacrylate) and Ionic Liquids.
Amajjahe S, Choi S, Munteanu M, Ritter H.
Institut für Organische Chemie und Makromolekulare Chemie II, Heinrich-Heine-Universität Düsseldorf, Universitätsstrasse 1,40225 Düsseldorf, Germany, Fax: (+49) 211-8115-840.
Protein Crystallography through Supramolecular Interactions between a Lanthanide Complex and Arginine.
Pompidor G, D\’Aléo A, Vicat J, Toupet L, Giraud N, Kahn R, Maury O.
Institut de Biologie Structurale J.-P. Ebel, UMR 5075 CEA-CNRS-UJF-PSB, 41 rue Jules Horowitz, 38027 Grenoble cedex 1, France.
Measurement of Amyloid Fibril Length Distributions by Inclusion of Rotational Motion in Solution NMR Diffusion Measurements.
Baldwin AJ, Anthony-Cahill SJ, Knowles TP, Lippens G, Christodoulou J, Barker PD, Dobson CM.
Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, UK, Fax: (+44) 1223 336-362.
Mesoporous Carbon Materials: Synthesis and Modification.
Porous carbon materials are of interest in many applications because of their high surface area and physicochemical properties. Conventional syntheses can only produce randomly porous materials, with little control over the pore-size distributions, let alone mesostructures. Recent breakthroughs in the preparation of other porous materials have resulted in the development of methods for the preparation of mesoporous carbon materials with extremely high surface areas and ordered mesostructures, with potential applications as catalysts, separation media, and advanced electronic materials in many scientific disciplines. Current syntheses can be categorized as either hard-template or soft-template methods. Both are examined in this Review along with procedures for surface functionalization of the carbon materials obtained.
Liang C, Li Z, Dai S.
P.O. Box 2008, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA, Fax: (+1) 865-576-5235.
Novel DNA Catalysts Based on G-Quadruplex Recognition.
Tang Z, Gonçalves DP, Wieland M, Marx A, Hartig JS.
Department of Chemistry, University of Konstanz, Universitätsstrasse 10, 78457 Konstanz, Germany, Fax: (+49) 7531-88-5140.
The Acylation and Phosphorylation Pattern of Lipid A from Xanthomonas Campestris Strongly Influence its Ability to Trigger the Innate Immune Response in Arabidopsis.
Lipopolysaccharides (LPSs) are major components of the cell surface of Gram-negative bacteria. LPSs comprise a hydrophilic heteropolysaccharide (formed by the core oligosaccharide and the O-specific polysaccharide) that is covalently linked to the glycolipid moiety lipid A, which anchors these macromolecules to the external membrane. LPSs are one of a group of molecules called pathogen-associated molecular patterns (PAMPs) that are indispensable for bacterial growth and viability, and act to trigger innate defense responses in eukaryotes. We have previously shown that LPS from the plant pathogen Xanthomonas campestris pv. campestris (Xcc) can elicit defense responses in the model plant Arabidopsis thaliana. Here we have extended these studies by analysis of the structure and biological activity of LPS from a nonpathogenic Xcc mutant, strain 8530. We show that this Xcc strain is defective in core completion and introduces significant modification in the lipid A region, which involves the degree of acylation and nonstoichiometric substitution of the phosphate groups with phosphoethanolamine. Lipid A that was isolated from Xcc strain 8530 did not have the ability to induce the defense-related gene PR1 in Arabidopsis, or to prevent the hypersensitive response (HR) that is caused by avirulent bacteria as the lipid A from the wild-type could. This suggests that Xcc has the capacity to modify the structure of the lipid A to reduce its activity as a PAMP. We speculate that such effects might occur in wild-type bacteria that are exposed to stresses such as those that might be encountered during plant colonization and disease.
Silipo A, Sturiale L, Garozzo D, Erbs G, Poulsen TT, Lanzetta R, Dow JM, Parrilli M, Newman MA, Molinaro A.
Dipartimento di Chimica Organica e Biochimica, Università di Napoli “Federico IIâ€, Complesso Universitario Monte S. Angelo, Via Cintia 4, 80126 Napoli, Italy, Fax: (+39) 081-674393.
Linear Analogues of Human beta-Defensin 3: Concepts for Design of Antimicrobial Peptides with Reduced Cytotoxicity to Mammalian Cells.
A series of engineered linear analogues [coded as F6, W6, Y6, A6, S6 and C(Acm)6] were modeled, designed, synthesized and structurally characterized by mass spectra, circular dichroism, hydrophobicity analysis and molecular modeling. We have screened antimicrobial activity, hemolysis to rabbit erythrocytes, and cytotoxicity to human conjunctival epithelial cells. No significant hemolytic effect was observed for hBD3 or from five of the six analogues [F6, Y6, A6, S6 and C(Acm)6] over the range of 3-100 mug mL(-1). The six linear analogues have reduced cytotoxicity to human conjunctival epithelial cells over the range of 6-100 mug mL(-1) compared to hBD3. By tuning the overall hydrophobicity of linear hBD3 analogues, reduced cytotoxicity and hemolysis were obtained while preserving the antimicrobial properties. The decreased cytotoxicity of the linear analogues is suggested to be structurally related to the removal of disulfide bridges, and the flexible structure of the linear forms, which seem to be associated with loss of secondary structure. These results suggest a new approach for guiding the design of new linear analogues of defensin peptides with strong antibiotic properties and reduced cytotoxicity to mammalian cells.
Liu S, Zhou L, Li J, Suresh A, Verma C, Foo YH, Yap EP, Tan DT, Beuerman RW.
Singapore Eye Research Institute, 11 Third Hospital Avenue, #06-00, Singapore 16875, Singapore, Fax: (+65) 6322-4599.
Disruption of Pichia pastoris PMR1 gene decreases its folding capacity on human serum albumin and interferon-alpha2b fusion protein.
In an attempt to increase the secretion capacity of Pichia pastoris (Pp), PpPMR1 gene was disrupted with GS115 as parent strain, and the resultant mutant was designated as Pppmr1. Pppmr1 displayed a Ca(2+)-dependent growth defect, which was consistent with the PMR1 mutation in other yeasts. HSA-L5-IFNalpha2b, a human serum albumin (HSA) and inferferon-alpha2b (IFNalpha2b) fusion protein with a flexible linker of 5 amino acid residues, was employed as a reporter to study the effects of PpPMR1 disruption on the secretion of heterologous protein. Because of its decreased viability after induction, Pppmr1 secreted more HSA-L5-IFNalpha2b only during the early phase (the first 15 hours) of induction. Although HSA-L5-IFNalpha2b secreted from GS115 and Pppmr1 had similar antiviral activity, the latter was heterogeneous (migrated as doublets on non-reducing SDS-PAGE) and unstable (prone to aggregation at neutral to mild alkaline pH). Site-directed mutagenesis revealed that the heterogeneity of HSA-L5-IFNalpha2b secreted from Pppmr1 was originated from the incomplete disulphide bridge pairing between Cys1 and Cys98 of IFNalpha2b. To be secreted homogeneously from Pppmr1 and to be stable in aqueous solution, the linker of the fusion protein should be extended to 10 amino acid residues. Copyright (c) 2008 John Wiley & Sons, Ltd.
Zhao HL, Xue C, Wang Y, Duan QF, Xiong XH, Yao XQ, Liu ZM.
Department of Microorganism Engineering, Beijing Institute of Biotechnology, 20 Dongdajie Street, Fengtai District, Beijing 100071, People\’s Republic of China.
A vector system for efficient and economical switching of C-terminal epitope tags in Saccharomyces cerevisiae.
In Saccharomyces cerevisiae, one-step PCR-mediated modification of chromosomal genes allows fast and efficient tagging of yeast proteins with various epitopes at the C- or N-terminus. For many purposes, C-terminal tagging is advantageous in that the expression pattern of epitope tag is comparable to that of the authentic protein and the possibility for the tag to affect normal folding of polypeptide chain during translation is minimized. As experiments are getting complicated, it is often necessary to construct several fusion proteins tagged with various kinds of epitopes. Here, we describe development of a series of plasmids that allow efficient and economical switching of C-terminally tagged epitopes, using just one set of universal oligonucleotide primers. Containing a variety of epitopes (GFP, TAP, GST, Myc, HA and FLAG tag) and Kluyveromyces lactis URA3 gene as a selectable marker, the plasmids can be used to replace any MX6 module-based C-terminal epitope tag with one of the six epitopes. Furthermore, the plasmids also allow additional C-terminal epitope tagging of proteins in yeast cells that already carry MX6 module-based gene deletion or C-terminal epitope tag. Copyright (c) 2008 John Wiley & Sons, Ltd.
Sung MK, Ha CW, Huh WK.
School of Biological Sciences and Research Center for Functional Cellulomics, Institute of Microbiology, Seoul National University, Seoul 151â€747, Republic of Korea.
Ghrelin: a new peptide regulating the neurohormonal system, energy homeostasis and glucose metabolism.
Identification of ghrelin started with the discovery of growth hormone secretagogues, continued with the description of ghrelin receptors and ended with the elucidation of the chemical structure of ghrelin. However, several issues concerning the role of ghrelin in physiological and pathophysiological processes are still under investigation. Most of the ghrelin produced in the body is secreted in the stomach, but it is also expressed in the hypothalamus, pituitary, pancreas, intestine, kidney, heart and gonads. Ghrelin stimulates growth hormone secretion via growth hormone secretagogue receptors. Ghrelin secretion in the stomach depends on both acute and chronic changes in nutritional status and energy balance. Current data support the hypothesis that the stomach, in addition to its important role in digestion, not only influences pituitary hormone secretion but, via ghrelin production, it also sends orexigenic (appetite increasing) signals to hypothalamic nuclei involved in the regulation of energy homeostasis. In addition to these main effects, ghrelin influences insulin secretion and glucose metabolism and it may exert potentially important effects on cardiovascular and gastrointestinal functions. Because of its effects on a large number of physiological functions, ghrelin may be involved in the pathomechanism of several human disorders, including disturbances of appetite, energy homeostasis and glucose metabolism. Further research might lead to a better understanding of the pathophysiology of ghrelin and might provide more effective therapy for the above disorders. Copyright (c) 2008 John Wiley & Sons, Ltd.
Pusztai P, Sarman B, Ruzicska E, Toke J, Racz K, Somogyi A, Tulassay Z.
2nd Department of Medicine, Semmelweis University, Budapest, Hungary.
