Molecular recognition of N-acetyltryptophan enantiomers by β-cyclodextrin

The enantioselectivity of β-cyclodextrin (β-CD) towards L- and D-N-acetyltryptophan (NAcTrp) has been studied in aqueous solution and the crystalline state. NMR studies in solution show that β-CD forms complexes of very similar but not identical geometry with both L- and D-NAcTrp and exhibits stronger binding with L-NAcTrp. In the crystalline state, only β-CD-L-NAcTrp crystallizes readily from aqueous solutions as a dimeric complex (two hosts enclosing two guest molecules). In contrast, crystals of the complex β-CD-D-NAcTrp were never obtained, although numerous conditions were tried. In aqueous solution, the orientation of the guest in both complexes is different than in the β-CD-L-NAcTrp complex in the crystal. Overall, the study shows that subtle differences observed between the β-CD-L,D-NAcTrp complexes in aqueous solution are magnified at the onset of crystallization, as a consequence of accumulation of many soft host-guest interactions and of the imposed crystallographic order, thus resulting in very dissimilar propensity of each enantiomer to produce crystals with β-CD

4-Chloro-2-[(E)-2-(4-methoxy­phen­yl)ethyl­imino­meth­yl]phenol

In the title Schiff base, C16H16ClNO2, the 2-(4-methoxy­phen­yl)ethyl (CH3OC6H4CH2CH2–; r.m.s. deviation = 0.10 Å) and 4-chloro-2-(imino­meth­yl)phenol (N=CHC6H3ClOH; r.m.s. deviation = 0.01 Å) portions are both essentially planar, the two parts being inclined at an angle of 61.8 (1)°. The hydroxy group forms a hydrogen bond to the imino N atom

2-Eth­oxy-6-[(methyl­imino)­meth­yl]phenol

In the title compound, C10H13NO2, synthesized by the reaction of 2-hy­droxy-3-eth­oxy­benzaldehyde with methyl­amine, there is an an intra­molecular O—H⋯N hydrogen bond involving the hy­droxy substituent and the amino N atom. In the crystal, mol­ecules form inversion dimers connected by pairs of C—H⋯O hydrogen bonds

第885回千葉医学会例会・千葉大学第二外科例会

<p><b>A</b>. NMDS ordination of 16S rRNA gene-derived microbial community structure. Similarity profile analysis, an <i>a priori</i> statistical approach that uses permutation to identify groups of communities that are more dissimilar than expected by chance, identified two distinct clusters of communities. Ellipses represent the 95% confidence intervals around the centroid for each cluster (the spatial mean in NMDS space of the communities belonging to each cluster). Lines emanating from the centroids indicate to which cluster each community belongs. Bacterial families well-correlated with the ordination (r² > 0.40) are displayed; vector length is proportional to the Pearson correlation coefficient for each family and vector direction corresponds to the direction of increasing abundance relative to the ordinated communities. Legend indicates the dune from which each ordinated community originated. Final 2-dimensional stress of the ordination is 0.12. <b>B</b>. Linear discriminant analysis (LDA) of bacterial classes indicates that the two clusters of microbial communities identified by similarity profile analysis are driven by the disparity between a high abundance of <i>Gammaproteobacteria</i> in one set of communities and more diverse population in the other set of communities. Only classes with effect size > 2.0 are displayed. <b>C</b>. NMDS ordination is based only on samples for which environmental parameters were measured. Parameters with r² > 0.1 are displayed. Final 2-dimensional stress of the ordination is 0.07.</p

The Metagenomics and Metadesign of the Subways and Urban Biomes (MetaSUB) International Consortium inaugural meeting report

The Metagenomics and Metadesign of the Subways and Urban Biomes (MetaSUB) International Consortium is a novel, interdisciplinary initiative comprised of experts across many fields, including genomics, data analysis, engineering, public health, and architecture. The ultimate goal of the MetaSUB Consortium is to improve city utilization and planning through the detection, measurement, and design of metagenomics within urban environments. Although continual measures occur for temperature, air pressure, weather, and human activity, including longitudinal, cross-kingdom ecosystem dynamics can alter and improve the design of cities. The MetaSUB Consortium is aiding these efforts by developing and testing metagenomic methods and standards, including optimized methods for sample collection, DNA/RNA isolation, taxa characterization, and data visualization. The data produced by the consortium can aid city planners, public health officials, and architectural designers. In addition, the study will continue to lead to the discovery of new species, global maps of antimicrobial resistance (AMR) markers, and novel biosynthetic gene clusters (BGCs). Finally, we note that engineered metagenomic ecosystems can help enable more responsive, safer, and quantified cities

Crystalographic study of biological macromolecules: I. Myomesin immunoglobulin domains 9-11 II. Cyclodextrin inclusion complexes

Myomesin is one of the main components of the sarcomeric M-line and is expressed in all kinds of cross-striated muscles investigated so far. It is comprised of 13 immunoglobulin (Ig) and fibronectin III (Fn) domains of differing sequence. The myomesin C-terminal region is organized along the titin molecule and the formed complex constitutes the central region of the M-line. The present study deals with the structural characterization of the C-terminal region of myomesin, which consists of the Ig domains 9-13. Specifically, the crystal structures of the truncated myomesin proteins My10-My11 and My9-M11 were studied by X-ray crystallography. In the studied structures, the Ig domains possess the characteristic β-"sandwich" arrangement, and every domain is connected to the next by an α-helix, a phenomenon described for the first time in proteins of the sarcomere. The present study, associated with the knowledge of the My12-M13 crystal structure, can result the establishment of a model for the C-terminal region of myomesin. At the second part of this thesis, the crystal structures of two β-cyclodextrin (β-CD) inclusion complexes were studied. The structure of the β-cyclodextrin - 4-pyridinealdazine complex is a novel structure both in terms of the arrangement of the β-CD molecules, that form a trimer, and in the guest molecules association. In the structure of the β-CD - N-acetyl-L-tryptophan complex, the CD molecules form dimers, generated by interactions between the atoms O3n_A...03(8-n)_B and form channels along the a axis. Inside the CD dimer two L-tryptophan molecules are enclosed, in a head to head conformation. Comparison of the reported structure and of the structure of the β-CD - N-acetyl-D-tryptophan complex can provide direct information regarding the mechanism of chiral recognition by the β-CD molecules.Η μυομεσίνη είναι μία από τις κύριες πρωτεΐνες της σαρκομεριδικής Μ γραμμής. Απαρτίζεται κυρίως από 13 διακριτές πρωτεϊνικές περιοχές με δομή ανοσοσφαιρίνης και ινωδογόνου III και εκφράζεται σε όλα τα είδη γραμμωτών μυών που έχουν μελετηθεί μέχρι σήμερα. Το καρβοξυτελικό άκρο της μυομεσίνης οργανώνεται κατά μήκος του μορίου της τιτίνης και το σύμπλοκο αυτό αποτελεί το κεντρικό μέρος της Μ γραμμής. Η παρούσα διατριβή αναφέρεται στο δομικό χαρακτηρισμό του καρβοξυτελικού άκρου της μυομεσίνης, το οποίο αποτελείται από τις ανοσοσφαιρινικές περιοχές 9-13. Συγκεκριμένα, μελετήθηκαν με κρυσταλλογραφία ακτινών Χ οι δομές των πρωτεϊνών My10-My11 και My9-My11. Στις μελετώμενες δομές, οι ανοσοσφαιρινικές περιοχές έχουν τη χαρακτηριστική διαμόρφωση β-«sandwich», ενώ κάθε περιοχή συνδέεται με τη γειτονική της μέσω μίας α-έλικας, φαινόμενο που παρατηρείται για πρώτη φορά σε πρωτεΐνες του σαρκομεριδίου. Η παρούσα μελέτη, σε συνδυασμό με την ήδη δημοσιευμένη κρυσταλλική δομή της My12-My13, επιτρέπει την εξαγωγή ενός δομικού μοντέλου για το σύνολο του καρβοξυτελικού άκρου της μυομεσίνης. Στο δεύτερο μέρος της παρούσας διατριβής μελετήθηκαν δύο σύμπλοκα εγκλεισμού της β-κυκλοδεξτρίνης. Η δομή του συμπλόκου β-κυκλοδεξτρίνης-4-πυριδιναλδαζίνης απεδείχθη καινοφανής τόσο ως προς τη διευθέτηση των μορίων της β-κυκλοδεξτρίνης, τα οποία δημιουργούν ένα τριμερές, όσο και ως προς τη διάταξη των ξενιζομένων μορίων στην υδροφοβική κοιλότητα και αποδεικνύει την πολυλειτουργικότητα του μορίου της β-κυκλοδεξτρίνης. Στη δομή του συμπλόκου β-κυκλοδεξτρίνης - Ν-ακέτυλο-L-θρυπτοφάνης, τα μόρια του ξενιστή σχηματίζουν διμερή στα οποία εγκλείονται δύο ξενιζόμενα μόρια. Σύγκριση της δομής αυτής με τη δομή του συμπλόκου β-κυκλοδεξτρίνης- Ν-ακέτυλο-D-θρυπτοφάνης θα βοηθήσει στην κατανόηση των παραγόντων που διέπουν τη χειρομορφική αναγνώριση από μόρια β-κυκλοδεξτρίνης

The effect of long-term mercury contamination on the composition and diversity of soil bacterial communities in riverine ecosystems

Hg contamination in riverine ecosystems is a persistent problem and clean-up efforts are a priority for EPA and local federal governments as potential methylation of Hg increases its toxicity due to its bioaccumulation and biomagnification in aquatic food chains. Understanding the microbial contribution to Hg contamination is of particular importance as microbial communities occupy the base of the food chain and the way they transform Hg has bottom-up effects to all trophic levels. The broad objective of this dissertation was to investigate the role of abiotic factors in shaping the composition, diversity and distribution of bacterial communities inhabiting floodplain soils of the East Fork Poplar Creek (EFPC), TN, and South River (SR), VA, chronically contaminated with Hg as a result of industrial processes. Analysis of soil samples from the EFPC by direct cultivation and isolation, revealed a metabolic-dependent effect of Hg-stress on bacterial populations, with copiotrophs exhibiting higher mercury reduction potentials, as well as phylogenetic and functional diversity, than oligotrophs. As the great majority of the strains contained a merA gene in their genome, Hg-resistance in these isolates may have been conferred by the functions of the mercury resistance (mer) system. A total of 27 phylogenetic incongruencies were observed between this and the 16S rRNA genes of the isolates, suggesting that horizontal gene transfer may play a role in Hg adaptation. The culture-independent method of 16S rRNA-fingerprinting was used to assess spatial distribution and diversity of bacterial communities along the Hg-contamination gradient in SR. Higher levels of diversity were obtained in communities that experience low as compared to high soil Hg levels. The best predictors of community diversity were pH, moisture and soil texture, whereas THg and geography were poor predictors. In this study a new merA-based t-RFLP method was designed to assess distribution and diversity of merA genes. Results show high levels of diversity for this gene and clustering based on geographical proximity. These findings highlight the impact of long-term Hg-stress on microbial communities in riverine ecosystems and provide a micro-ecological framework for future remedial actions in Hg contaminated sites.Ph. D.Includes bibliographical referencesIncludes vitaby Aspassia D. Chatziefthimio

Intracellular action of magnesium in airways smooth muscle relaxation in rabbit

This study was designed to examine whether magnesium has an intracellular action on airways smooth muscle contraction. Tracheal muscle strips were obtained from six male rabbits and perfused in a bathing chamber. The muscle was incubated in Krebs solution for 15 min. Then, the bath solution was changed to a Ca++ free (calcium free) solution for 10 min. 10(-4) M Ach (acetyl choline) applied in the Ca++ free solution evoked a muscle contraction, at about 60% of initial contraction induced by 10 Ach in Krebs solution. After control contraction, magnesium sulfate (range 10(-4) - 1 M) was applied in Ca++ free solution. At each dose of magnesium pretreatment the response of the muscle to 10(-4) M Ach in Ca++ free solution was measured. Magnesium caused a decrease in Ach-induced contraction in a dose-dependent manner. 10(-1) M MgSO4 depressed to 13.28% of the contraction of Ach in Calcium free solution. The time to peak contraction and to washout, were also decreased. The concentration for 50% inhibition (IC50) of the maximal contraction was estimated to be 10(-3) M MgSO4. Re-admission of Krebs solution to muscle strip, resulted in contraction as a consequence of massive influx of Ca++ that occurs during the phase of Ca++ repletion. These data suggest that magnesium has an intracellular action and inhibits smooth muscle contraction in a Ca++ free solution probably by inhibiting Ca++ release from the sarcoplasmic reticulum

Magnesium as a relaxing factor of airway smooth muscles

in the search for effective treatment of a life-threatening asthma attack, intravenous magnesium infusion has been studied in asthmatic patients because of its potential effect to reverse bronchospasm and improve pulmonary function. To determine whether magnesium sulfate inhibits airway smooth muscle contraction and the possible mechanism of its action, in vitro experiments were performed on rabbit tracheas. Tracheal muscle strips were obtained from 12 rabbits. Initially, the muscle strip was pretreated with a solution containing MgSO4 (concentrations 10(-4) to 2 M) and 85 mM KCl. The response curve of the muscle was recorded. Application of the above solution led to a 40% relaxation at a magnesium concentration of 10(-1) M. The time to peak and to wash-out remained unchanged, and fixed to 66.6 and 123.3 sec, respectively, not influenced by magnesium concentration. On a second phase, the muscle strip was pretreated with KCI alone, and only after a full contractile response was obtained did we add 10(-1) M MgSO4, which led to full relaxation. We follow the same protocol using 10(-4) M acetylcholine (ACH). In this case, simultaneous application of 10(-1) M MgSO4 caused a 55.1% decrease in muscle contraction and a 60% decrease in time to peak. On a second phase, we added magnesium as we did with KCI, but without the same result. Magnesium caused a full relaxation when the constrictor agent was KCI, but a residual contraction was observed when the constrictor was ACH. Based on the knowledge that ACH and KCI cause Ca2+ influx into the cells and subsequent contraction by acting on different Ca2+ channels, we concluded that magnesium inhibits Ca2+ influx by blocking the voltage-dependent calcium channels