Search results for "Magnesium"

Mineral profile of kaki fruits (Diospyros kaki L.)

2015

The main objective of this study was the determination of the mineral profile of 167 kaki fruit (Diospyros kaki L.) samples produced from different regions of Spain, including samples with the protected designation of origin (PDO) 'Kaki Ribera del Xúquer' Valencia (Spain). Samples were analysed by inductively coupled plasma optical emission spectroscopy (ICP-OES) and inductively coupled plasma mass spectrometry (ICP-MS). Consumption of one piece of kaki fruit (200-400 g) would give a mineral intake providing 1-10% of the recommended daily allowance (RDA) for calcium, 1-30% for copper and potassium, 1-15% from iron and magnesium, up to 1% of sodium, and up to 4% of zinc. ANOVA analysis indic…

Numerical investigation on dissimilar Friction Stir Welding of Aluminum and Magnesium sheets

2014

All-atom simulations disentangle the functional dynamics underlying gene maturation in the intron lariat spliceosome

2018

The spliceosome (SPL) is a majestic macromolecular machinery composed of five small nuclear RNAs and hundreds of proteins. SPL removes noncoding introns from precursor messenger RNAs (pre-mRNAs) and ligates coding exons, giving rise to functional mRNAs. Building on the first SPL structure solved at near–atomic-level resolution, here we elucidate the functional dynamics of the intron lariat spliceosome (ILS) complex through multi-microsecond-long molecular-dynamics simulations of ∼1,000,000 atoms models. The ILS essential dynamics unveils (i) the leading role of the Spp42 protein, which heads the gene maturation by tuning the motions of distinct SPL components, and (ii) the critical particip…

Fe- but not Mg-protophorphyrin IX binds to a transmembrane b-type cytochrome.

2013

Transmembrane b-type cytochromes, which are crucially involved in electron transfer chains, bind one or more heme (Fe-protoporphyrin IX) molecules non-covalently. Similarly, chlorophylls are typically also non-covalently bound by several membrane integral polypeptides involved in photosynthesis. While both, chlorophyll and heme, are tetrapyrrole macrocycles, they have different substituents at the tetrapyrrole ring moiety. Furthermore, the central metal ion is Mg(2+) in chlorophyll and Fe(2+/3+) in heme. As heme and chlorophyll a have similar structures and might both be ligated by two histidine residues of a polypeptide chain, and as the local concentration of chlorophyll a might be up to …

alpha 11beta 1 integrin recognizes the GFOGER sequence in interstitial collagens.

2002

The integrins alpha(1)beta(1), alpha(2)beta(1), alpha(10)beta(1), and alpha(11)beta(1) are referred to as a collagen receptor subgroup of the integrin family. Recently, both alpha(1)beta(1) and alpha(2)beta(1) integrins have been shown to recognize triple-helical GFOGER (where single letter amino acid nomenclature is used, O = hydroxyproline) or GFOGER-like motifs found in collagens, despite their distinct binding specificity for various collagen subtypes. In the present study we have investigated the mechanism whereby the latest member in the integrin family, alpha(11)beta(1), recognizes collagens using C2C12 cells transfected with alpha(11) cDNA and the bacterially expressed recombinant a…

Selective "one-pot" synthesis of functionalized cyclopentenones.

2012

Double addition (1,2-1,4) of vinyl magnesium bromide to squaric acid derivatives allows the preparation of polyoxygenated cyclopentenones (8) in a "one-pot" procedure. The reaction occurs through the intermediate formation of octatetraenes (6). Protonation of this latter intermediate at -78 °C with TFE occurs selectively at the vinyl CH(2) closer to the metallic centers. DFT studies of the cyclization step justify the observed diastereoselectivity.

Understanding the different activities of highly promiscuous MbtI by computational methods

2012

Salicylate synthase from Mycobacterium tuberculosis, MbtI, is a highly promiscuous Mg(2+) dependent enzyme with up to four distinct activities detected in vitro: isochorismate synthase (IS), isochorismate pyruvate lyase (IPL), salicylate synthase (SS) and chorismate mutase (CM). In this paper, Molecular Dynamic (MD) simulations employing hybrid quantum mechanics/molecular mechanics (QM/MM) potentials have been carried out to get a detailed knowledge of the IS and the IPL activities at the molecular level. According to our simulations, the architecture of the MbtI active site allows catalyzing the two reactions: the isochorismate formation, by means of a stepwise mechanism, and the salicylat…

Exploring the redox reactivity of magnesium porphine. Insight into the origins of electropolymerisation.

2010

International audience; Magnesium(II) porphine, MgP (1), was synthesised according to the Lindsey procedure allowing to isolate and crystallise 1-formyldipyrromethane (2) as a synthetic intermediate. Unprecedented Xray diffraction studies revealed multiple intermolecular associations in the crystal between neighbouring units of 2, namely hydrogen bond and CH … π. The electrochemical behaviour of 1 was examined by means of cyclic voltammetry. In oxydation, two well-defined and distinct steps are assigned to macrocycle concerned electron transfers yielding initially the π-cation radical and π dication, respectively. The highly reactive dication condenses neutral magnesium porphine to form a d…

A Quantum Mechanic/Molecular Mechanic Study of the Wild-Type and N155S Mutant HIV-1 Integrase Complexed with Diketo Acid

2008

Integrase (IN) is one of the three human immunodeficiency virus type 1 (HIV-1) enzymes essential for effective viral replication. Recently, mutation studies have been reported that have shown that a certain degree of viral resistance to diketo acids (DKAs) appears when some amino acid residues of the IN active site are mutated. Mutations represent a fascinating experimental challenge, and we invite theoretical simulations for the disclosure of still unexplored features of enzyme reactions. The aim of this work is to understand the molecular mechanisms of HIV-1 IN drug resistance, which will be useful for designing anti-HIV inhibitors with unique resistance profiles. In this study, we use mo…

Jararhagin-derived RKKH Peptides Induce Structural Changes in α1I Domain of Human Integrin α1β1

2003

Integrin alpha(1)beta(1) is one of four collagen-binding integrins in humans. Collagens bind to the alphaI domain and in the case of alpha(2)I collagen binding is competitively inhibited by peptides containing the RKKH sequence and derived from the metalloproteinase jararhagin of snake venom from Bothrops jararaca. In alpha(2)I, these peptides bind near the metal ion-dependent adhesion site (MIDAS), where a collagen (I)-like peptide is known to bind; magnesium is required for binding. Published structures of the ligand-bound "open" conformation of alpha(2)I differs significantly from the "closed" conformation seen in the structure of apo-alpha(2)I near MIDAS. Here we show that two peptides,…