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Monovalent Anions (monovalent + anion)
Selected AbstractsEffects of hydrophobicity and anions on self-assembly of the peptide EMK16-IIBIOPOLYMERS, Issue 4 2010Dawei Zou Abstract Effects of hydrophobic and electrostatic interactions on the self-assembling process of the ionic-complementary peptide EMK16-II are investigated by atomic force microscopy imaging, circular dichroism spectra, light scattering, and chromatography. It is found that the hydrophobicity of the peptide promotes the aggregation in pure water even at a very low concentration, resulting in a much lower critical aggregation concentration than that of another peptide, EAK16-II. The effect of anions in solution with different valences on electrostatic interactions is also important. Monovalent anions (Cl, and Ac,) with a proper concentration can facilitate the formation of peptide fibrils, with Cl, of smaller size being more effective than Ac, of larger size. However, only small amounts of fibrils, but plenty of large amorphous aggregates, are found when the peptide solution is incubated with multivalent anions, such as SO, C6H5O, and HPO. More importantly, by gel filtration chromatography, the citrate anion, which induces a similar effect on the self-assembling process of EMK16-II as that of SO and HPO, can interact with two or more positively charged residues of the peptide and reside in the amorphous aggregates. This implies a "salt bridge" effect of multivalent anions on the peptide self-assembling process, which can interpret a previous puzzle why divalent cations inhibit the formation of ordered nanofibrils of the ionic-complementary peptides. Thus, our results clarify the important effects of hydrophobic and electrostatic interactions on the self-assembling process of the ionic-complementary peptides. These are greatly helpful for us to understand the mechanism of peptides' self-assembling process and protein folding and aggregation. © 2009 Wiley Periodicals, Inc. Biopolymers 93: 318,329, 2010. This article was originally published online as an acceptedpreprint. The "Published Online" date corresponds to the preprintversion. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com [source] Interaction between a dislocation and monovalent anion in various alkali halide crystalsCRYSTAL RESEARCH AND TECHNOLOGY, Issue 10 2010Y. KohzukiArticle first published online: 30 AUG 2010 Abstract It was investigated from (L0/L)2 versus ,0 curve that the Friedel relation between the effective stress and the average length of dislocation segments, L, is appropriate for the interaction between a dislocation and the monovalent anion in various alkali halides single crystals (NaCl: Br - , NaBr: Cl - or I - , KCl: Br - or I - , and RbCl: Br - or I - ). Here, L0 represents the average spacing of monovalent anions on a slip plane and ,0 is the bending angle at which the dislocation breaks away from the anion at the temperature of 0 K. This is because the anions are the weak obstacles such as impede the dislocation at ,0 above about 150 degrees, where the Friedel relation agrees with the Fleischer one (L02 = L2(,,,0)/2). Furthermore, the values of (L /L0) were found to be within 4.05 to 5.87 for the crystals. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Ion-dependent gating of kainate receptorsTHE JOURNAL OF PHYSIOLOGY, Issue 1 2010Derek Bowie Ligand-gated ion channels are an important class of signalling protein that depend on small chemical neurotransmitters such as acetylcholine, l -glutamate, glycine and ,-aminobutyrate for activation. Although numerous in number, neurotransmitter substances have always been thought to drive the receptor complex into the open state in much the same way and not rely substantially on other factors. However, recent work on kainate-type (KAR) ionotropic glutamate receptors (iGluRs) has identified an exception to this rule. Here, the activation process fails to occur unless external monovalent anions and cations are present. This absolute requirement of ions singles out KARs from all other ligand-gated ion channels, including closely related AMPA- and NMDA-type iGluR family members. The uniqueness of ion-dependent gating has earmarked this feature of KARs as a putative target for the development of selective ligands; a prospect all the more compelling with the recent elucidation of distinct anion and cation binding pockets. Despite these advances, much remains to be resolved. For example, it is still not clear how ion effects on KARs impacts glutamatergic transmission. I conclude by speculating that further analysis of ion-dependent gating may provide clues into how functionally diverse iGluRs families emerged by evolution. Consequently, ion-dependent gating of KARs looks set to continue to be a subject of topical inquiry well into the future. [source] Structural effects of monovalent anions on polymorphic lysozyme crystalsACTA CRYSTALLOGRAPHICA SECTION D, Issue 7 2001M. C. Vaney Understanding direct salt effects on protein crystal polymorphism is addressed by comparing different crystal forms (triclinic, monoclinic, tetragonal and orthorhombic) for hen, turkey, bob white quail and human lysozymes. Four new structures of hen egg-white lysozyme are reported: crystals grown in the presence of NapTS diffracted to 1.85,Å, of NaI to 1.6,Å, of NaNO3 to 1.45,Å and of KSCN to 1.63,Å. These new structures are compared with previously published structures in order to draw a mapping of the surface of different lysozymes interacting with monovalent anions, such as nitrate, chloride, iodide, bromide and thiocyanate. An analysis of the structural sites of these anions in the various lysozyme structures is presented. This study shows common anion sites whatever the crystal form and the chemical nature of anions, while others seem specific to a given geometry and a particular charge environment induced by the crystal packing. [source] | ||||||||||