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ISOLATION OF ANTI-ANAEMIC FACTOR PRESENT IN RAW LIVER.

Methyleleamino-acetonitrile has been condensed with various aldehydes to yield some amino-acids. The method is capable of being extended in various directions. 3-Aminocoumarin derivatives can also be prepared from methyleneamino-acetonitrile.

Homology modelling of the human eIF-5A protein has been performed by using a multiple predictions strategy. As the sequence identity between the target and the template proteins is nearly 30%, which is lower than the commonly used threshold to apply with confidence the homology modelling method, we developed a specific predictive scheme by combining different sequence analyses and predictions, as well as model validation by comparison to structural experimental information. The target sequence has been used to find homologues within sequence databases and a multiple alignment has been created. Secondary structure for each single protein has been predicted and compared on the basis of the multiple sequence alignment, in order to evaluate and adjust carefully any gap. Therefore, comparative modelling has been applied to create the model of the protein on the basis of the optimized sequence alignment. The quality of the model has been checked by computational methods and the structural features have been compared to experimental information, giving us a good validation of the reliability of the model and its correspondence to the protein structure in solution. Last, the model was deposited in the Protein Data Bank to be accessible for studies on the structure-function relationships of the human eIF-5A.

Solvothermal and classical synthesis with an identical recipe involving 4H-1,2,4-triazol-4-yl acetic acid (HL1) and CdCl2 afforded two-dimensional (2D) (1)l and one-dimensional (2) coordination polymers, respectively. Hexagonal plate-like crystals of [Cd-2(L1)(2)Cl-2] (1), which crystallize in the chiral orthorhombic space group (P2(1)2(1)2(1)), were obtained in high yield. The 1,2,4-triazole-4-yl acetate (Li? ligand, which has a significant kink in the spacer, leads to the formation of a Cd-II complex displaying a 2D single-stranded helical array. The pitch height of the helix is equal to the length of the crystallographic a axis (7.579 angstrom) which comprises two cadmium atoms and two ligands. Solid-state emission of 1 shows a strong emission band around 465 nm with photoexcitation at 290 nm. Mercury porosimetry measurements reveal pore size distribution with a diameter of 80, 10, and 1 mu m. BET shows no preference for N-2(g) but a low H-2(g) adsorption of 4 cm(3)/g. Complex 1, which is constituted by a "soft" nonaromatic network that begins to collapse around 170 C, was subjected to controlled pyrolysis to produce CdO with morphology and phase selectivity. Texture of the thus obtained pure cubic phase of CdO (beta-form) was further tuned with the regulation of the annealing temperature. Crystals of rectangular blocks of [Cd(HL1L1)Cl]center dot 2H(2)O (2), which were formed in small quantity, feature a centrosymmetric, monoclinic space group (P2(1)/c). Their crystal structure reveals a one-dimensional linear chain where Cd atoms are connected by a triple bridge made up of one mu-chloride and two mu-N1,N2-1,2,4-triazole HL1 and L1. The coordination polymer charge is balanced by both chloride and the carboxylate group of L1.

Understanding the binding mode of agonists to adrenergic receptors is crucial to enabling improved rational design of new therapeutic agents. However, so far the high conformational flexibility of G protein-coupled receptors has been an obstacle to obtaining structural information on agonist binding at atomic resolution. In this study, we report microsecond classical molecular dynamics simulations of β1 and β2 adrenergic receptors bound to the full agonist isoprenaline and in their unliganded form. These simulations show a novel agonist binding mode that differs from the one found for antagonists in the crystal structures and from the docking poses reported by in silico docking studies performed on rigid receptors. Internal water molecules contribute to the stabilization of novel interactions between ligand and receptor, both at the interface of helices V and VI with the catechol group of isoprenaline as well as at the interface of helices III and VII with the ethanolamine moiety of the ligand. Despite the fact that the characteristic N-C-C-OH motif is identical in the co-crystallized ligands and in the full agonist isoprenaline, the interaction network between this group and the anchor site formed by Asp(3.32) and Asn(7.39) is substantially different between agonists and inverse agonists/antagonists due to two water molecules that enter the cavity and contribute to the stabilization of a novel network of interactions. These new binding poses, together with observed conformational changes in the extracellular loops, suggest possible determinants of receptor specificity., Author Summary G-protein coupled receptors are the largest family of membrane proteins in the human genome and they constitute the largest class of drug targets. Amongst them, beta adrenergic receptors are involved in the regulation of muscular and vascular tone and are thus molecular targets for the treatment of various diseases including hypertension, heart failure and asthma. The function of these receptors is regulated via the binding of endogenous or exogenous ligands that can either lead to activation (agonists) or inactivation (inverse agonists/antagonists). However, structure determination of these receptors has been very elusive, and the few atomic resolution structures that are available so far have only been obtained in the presence of inverse agonists or antagonists. In order to study the binding mode of agonists inside the binding pocket, we employ all-atom molecular dynamics. This facilitates the study of the details of the interaction between agonist and receptor in full atomistic detail. We find that agonists binding to beta adrenergic receptors require the formation of a highly structured hydrogen bond network that is further stabilized by the presence of internal water molecules. The observed local rearrangements also help provide insights into the molecular origin of the differences between agonist and inverse agonist binding.

The application of click chemistry to develop libraries of organometallic ruthenium-arene complexes with potential anticancer properties has been investigated. A series of ruthenium-imidazole-triazole complexes, with hydrophobic tails, were prepared from a common precursor via click chemistry. The tail could be attached to the ligand prior to coordination to the ruthenium complex or following coordination, the former giving the product in superior yield. The complexes were screened for cytotoxicity in tumourigenic and non-tumourigenic cell lines, and while the compounds were only moderately cytotoxic, good selectivity for tumourigenic cells was observed. (C) 2010 Elsevier B.V. All rights reserved.

A high-resolution reference panel based on whole-genome sequencing data enables accurate imputation of HLA alleles across diverse populations and fine-mapping of HLA association signals for HIV-1 host response., Fine-mapping to plausible causal variation may be more effective in multi-ancestry cohorts, particularly in the MHC, which has population-specific structure. To enable such studies, we constructed a large (n = 21,546) HLA reference panel spanning five global populations based on whole-genome sequences. Despite population-specific long-range haplotypes, we demonstrated accurate imputation at G-group resolution (94.2%, 93.7%, 97.8% and 93.7% in admixed African (AA), East Asian (EAS), European (EUR) and Latino (LAT) populations). Applying HLA imputation to genome-wide association study data for HIV-1 viral load in three populations (EUR, AA and LAT), we obviated effects of previously reported associations from population-specific HIV studies and discovered a novel association at position 156 in HLA-B. We pinpointed the MHC association to three amino acid positions (97, 67 and 156) marking three consecutive pockets (C, B and D) within the HLA-B peptide-binding groove, explaining 12.9% of trait variance.

The rules for product ion formation in electron capture dissociation (ECD) mass spectrometry of peptides and proteins remain unclear. Random backbone cleavage probability and the nonspecific nature of ECD toward amino acid sequence have been reported, contrary to preferential channels of fragmentation in slow heating-based tandem mass spectrometry. Here we demonstrate that for amphipathic peptides and proteins, modulation of ECD product ion abundance (PIA) along the sequence is pronounced. Moreover, because of the specific primary (and presumably secondary) structure of amphipathic peptides, PIA in ECD demonstrates a clear and reproducible periodic sequence distribution. On the one hand, the period of ECD PIA corresponds to periodic distribution of spatially separated hydrophobic and hydrophilic domains within the peptide primary sequence. On the other hand, the same period correlates with secondary structure units, such as a-helical turns, known for solution-phase structure. Based on a number of examples, we formulate a set of characteristic features for ECD of amphipathic peptides and proteins: (1) periodic distribution of PIA is observed and is reproducible in a wide range of ECD parameters and on different experimental platforms; (2) local maxima of PIA are not necessarily located near the charged site; (3) ion activation before ECD not only extends product ion sequence coverage but also preserves ion yield modulation; (4) the most efficient cleavage (e.g. global maximum of ECD PIA distribution) can be remote from the charged site; (5) the number and location of PIA maxima correlate with amino acid hydrophobicity maxima generally to within a single amino acid displacement; and (6) preferential cleavage sites follow a selected hydrogen spine in an a-helical peptide segment. Presently proposed novel insights into ECD behavior are important for advancing understanding of the ECD mechanism, particularly the role of peptide sequence on PIA. An improved ECD model could facilitate protein sequencing and improve identification of unknown proteins in proteomics technologies. In structural biology, the periodic/preferential product ion yield in ECD of a-helical structures potentially opens the way toward de novo site-specific secondary structure determination of peptides and proteins in the gas phase and its correlation with solution-phase structure. (J Am Soc Mass Spectrom 2009, 20, 1182-1192) (C) 2009 Published by Elsevier Inc. on behalf of American Society for Mass Spectrometry