RESUMEN
The S-adenosyl-L-methionine dependent methylation of adenine 58 in the T-loop of tRNAs is essential for cell growth in yeast or for adaptation to high temperatures in thermophilic organisms. In contrast to bacterial and eukaryotic tRNA m(1)A58 methyltransferases that are site-specific, the homologous archaeal enzyme from Pyrococcus abyssi catalyzes the formation of m(1)A also at the adjacent position 57, m(1)A57 being a precursor of 1-methylinosine. We report here the crystal structure of P. abyssi tRNA m(1)A57/58 methyltransferase ((Pab)TrmI), in complex with S-adenosyl-L-methionine or S-adenosyl-L-homocysteine in three different space groups. The fold of the monomer and the tetrameric architecture are similar to those of the bacterial enzymes. However, the inter-monomer contacts exhibit unique features. In particular, four disulfide bonds contribute to the hyperthermostability of the archaeal enzyme since their mutation lowers the melting temperature by 16.5°C. His78 in conserved motif X, which is present only in TrmIs from the Thermococcocales order, lies near the active site and displays two alternative conformations. Mutagenesis indicates His78 is important for catalytic efficiency of (Pab)TrmI. When A59 is absent in tRNA(Asp), only A57 is modified. Identification of the methylated positions in tRNAAsp by mass spectrometry confirms that (Pab)TrmI methylates the first adenine of an AA sequence.
Asunto(s)
Adenina/metabolismo , Proteínas Arqueales/química , Pyrococcus abyssi/enzimología , ARN de Transferencia de Aspártico/metabolismo , ARNt Metiltransferasas/química , Proteínas Arqueales/genética , Proteínas Arqueales/metabolismo , Sitios de Unión , Dominio Catalítico , Cristalografía por Rayos X , Dimerización , Disulfuros/química , Estabilidad de Enzimas , Histidina/química , Modelos Moleculares , Mutación , ARN de Transferencia de Aspártico/química , S-Adenosilmetionina/química , ARNt Metiltransferasas/genética , ARNt Metiltransferasas/metabolismoRESUMEN
[This corrects the article DOI: 10.1021/acsomega.0c04501.].
RESUMEN
Idarubicin (IDA) is the analog of daunorubicin (DNR). The absence of the methoxy group at position 4 of IDA remarkably improved lipophilicity, which is responsible for extra cellular uptake, higher DNA-binding ability, and considerable cytotoxicity in correlation with doxorubicin (DOX) and DNR. In this paper, we conceived two principal objectives: we realized the crystal structure of IDA by X-ray diffraction measurements on single crystals at room temperature (monoclinic, space group P21, a = 5.1302(2) Å, b = 9.9122(5) Å, c = 24.8868(11) Å; ß = 91.425(4)°; V = 1265.14(10) Å3) with refinements of the structure converged to the final R = 3.87%. The second objective has been to develop gold nanoparticles encapsulated with idarubicin through an original methodology in which gold salt (HAuCl4) is chelated with IDA and diacid polymer (PEG) to form hybrid nanoparticles called IDA IN PEG-AuNPs in which drug solubility was enhanced. The computational studies were in agreement with the experimental observations. These hybrid nanoparticles and their precursors were analyzed by Raman, UV-Vis, 1H NMR, and transmission electron microscopy (TEM). The main results are completed by a theoretical approach to understand the whole process.
RESUMEN
The title compound, C(8)H(11)O(2)P, is a phosphinic compound with a tetra-coordinate penta-valent P atom. The phosphinic function plays a predominant role in the cohesion of the crystal structure, both by forming chains along the b axis via strong inter-molecular O-Hâ¯O hydrogen bonds and by cross-linking these chains perpendicularly via weak inter-molecular C-Hâ¯O hydrogen bonds, generating a two-dimensional network parallel to (001).
RESUMEN
In the title compound, H(3)O(+)·C(8)H(7)O(8)P(2) (-), the anions form inversion dimmers by way of pairs of O-Hâ¯O hydrogen bonds involving the phospho-nic functions and via the hydro-nium cation. Further O-Hâ¯O links involving the hydronium cation play a prominant part in the cohesion of the crystal structure by building bridges between bis-phospho-nate pairs, forming infinite ribbons along the b-axis direction and by cross-linking these ribbons perpendicularly along the a-axis direction, forming an infinite three-dimensional hydrogen-bond network. The benzene ring and the C=O atoms of the furan ring are disordered over two sets of positions of equal occupancy.
RESUMEN
Cyclodextrins are supramolecules widely used to help solubilization of hydrophobic molecules via host: guest complexation. To prepare the complexes, co-solvents like alcohols are mandatory and play an important role in the complexation process. In particular, the length of the aliphatic chain in primary linear alcohol can help the preparation and the stability of such complexes. The inclusion complexes of different linear aliphatic alcohols with beta cyclodextrin (ßCD) were prepared. The resultant complexes were analyzed in solution by proton nuclear magnetic resonance spectroscopy (1H NMR) and in the solid state by Differential Scanning Calorimetry (DSC) and powder X-ray diffraction (PXRD). Specific complexes are obtained in presence of alcohols longer than hexanol while the shorter alcohols act as a molecule of water solvent. Computations of energetic and thermodynamic properties followed by predictions of the more stable molecular structures for inclusion complexes by molecular modelling are in accordance with the experimental results.
RESUMEN
Thermotoga maritima contains a natural hybrid protein constituted of two moieties: a peroxiredoxin domain at the N-terminus and a nitroreductase domain at the C-terminus. The peroxiredoxin (Prx) domain has been overproduced and purified from Escherichia coli cells. The recombinant Prx domain, which is homologous to bacterial Prx BCP and plant Prx Q, folds properly into a stable protein that possesses biological activity. The recombinant protein was crystallized and synchrotron data were collected to 2.9 A resolution. The crystals belonged to the tetragonal space group I422, with unit-cell parameters a = b = 176.67, c = 141.20 A.
Asunto(s)
Proteínas Bacterianas/química , Peroxirredoxinas/química , Thermotoga maritima/química , Proteínas Bacterianas/genética , Proteínas Bacterianas/aislamiento & purificación , Clonación Molecular , Cristalografía por Rayos X , Peroxirredoxinas/genética , Peroxirredoxinas/aislamiento & purificación , Reacción en Cadena de la Polimerasa , Multimerización de Proteína , Proteínas Recombinantes/química , Proteínas Recombinantes/aislamiento & purificación , Thermotoga maritima/genéticaRESUMEN
The title compound, C(8)H(12)O(7)P(2)·CH(4)O, is a monoesterified bis-phospho-nate (or 1-hydroxy-methyl-ene-1,1-bis-phospho-nic acid). These synthetic compounds are widely used in medicine to inhibit bone resorption in diseases like osteoporosis, and are characterized by a stable P-C-P group and are thus analogs of inorganic pyrophosphate. By masking one or several ionizable groups, introduced as phosphono-ester, it was anti-cipated the formation of prodrugs with higher lipophilicity that could facilitate the drug delivery and metabolization. Mol-ecules are paired by inter-molecular hydrogen bonds involving the phospho-nic groups. In addition, dimers are connected side-by-side, building infinite ribbons along the a-axis direction; these ribbons are cross-linked perpendicularly along the b-axis direction via a methanol solvent mol-ecule (disordered over two sites with occupancy factors ca 0.6 and 0.4), forming an extended inter-molecular hydrogen-bonded network. The H atoms of the methyl group in the main molecule are disordered equally over two positions.
RESUMEN
The title compound, C(9)H(12)N(2)O(2)S, is a useful precursor of a variety of modified sulfonamide mol-ecules. Due to the importance of these mol-ecules in biological systems (antibacterials, antidepressants and many other applications), there is a growing inter-est in the discovery of new biologically active compounds. In the title compound, the mol-ecules are linked by N-Hâ¯O inter-molecular hydrogen bonds involving the sulfonamide function to form an infinite two-dimensional network parallel to the (001) plane.
RESUMEN
Among various cavitand molecules, cyclodextrins are extensively studied due to their ability to form host-guest complexes with small hydrophobic molecules. Aiming to explore cyclodextrin implementation on the scopes related to the environmental pollution monitoring or remediation, extensive studies for understanding the cyclodextrin-based host-guest complex formation with selected targeted substances are conducted. In this context, two polycyclic aromatic hydrocarbons, naphthalene and fluoranthene as well as toluene as a member of volatile organic compounds, were studied regarding their ability to encapsulate into cyclodextrin cavities. Synthesised complexes were examined by thermogravimetric analysis combined with Raman spectroscopy. The obtained results demonstrated that the size between targeted molecules and the cyclodextrin cavities strongly correlates with its ability to engage in complexation. Thus, this latter parameter plays an important role in the inclusion complex formation as well as in the strength of the interaction between the molecules.
Asunto(s)
Ciclodextrinas/química , Monitoreo del Ambiente/métodos , Hidrocarburos Policíclicos Aromáticos/análisis , Espectrometría Raman , Termogravimetría , Contaminantes Químicos del Agua/análisis , Monitoreo del Ambiente/instrumentaciónRESUMEN
In silico optimisation, synthesis and binding evaluation of αvß3 integrin's affinity for precursors of a new RGD peptidomimetics family are presented. The 2-pyrrolidinone building block was obtained by condensation of l-lysine with dimethoxydihydrofuran followed by reduction. The ring was functionalized with a carboxylic acid and a guanidinium appendage. On the pyrrolidinone heterocycle, the effects on affinity of position, length and relative geometry of the two acid or basic functionalized side chains introduced on the pyrrolidinone ring have been previously evaluated by docking studies. Peptidomimetics have finally been evaluated by competition binding assays for αvß3 integrin's affinity using radio-ligands.
Asunto(s)
Simulación por Computador , Oligopéptidos/química , Peptidomiméticos/síntesis química , Peptidomiméticos/metabolismo , Pirrolidinonas/síntesis química , Pirrolidinonas/metabolismo , Unión Competitiva , Técnicas de Química Sintética , Humanos , Integrina alfaVbeta3/química , Integrina alfaVbeta3/metabolismo , Simulación del Acoplamiento Molecular , Peptidomiméticos/química , Unión Proteica , Conformación Proteica , Pirrolidinonas/químicaRESUMEN
The solid-state structure of the complex of para-sulfonatocalix[4]arene with d-arginine, contains a water channel diagonal to a zigzag bilayer of the host, within the bilayer six crystallographically independent molecules of arginine are present, four being included in the calix cavities.
RESUMEN
OBJECTIVE: A minority of patients with ankylosing spondylitis (AS) fail to respond to infliximab treatment. This study compared the circulating infliximab concentration and the presence of clinical symptoms in patients continuously treated with infliximab or after treatment interruption. METHODS: Patients with active AS were randomly assigned at week 0 to receive infliximab either at weeks 4, 6, 10, and then every 6 weeks (continuous treatment), or at weeks 4, 6, and 10 and then upon symptom recurrence (on-demand treatment). The circulating concentration of infliximab was determined early during treatment and at weeks 46 and 52 for the continuous treatment group or upon relapse for the on-demand group. Response in the continuous treatment group was defined at week 58 using the ASsessment in AS International Working Group Criteria for 20% improvement. RESULTS: Among the 93 patients in the continuous treatment group, treatment failure was not associated with a low circulating concentration of infliximab, either during early treatment or at 1 year. Eleven (39.2%) of the 28 nonresponders had an infliximab concentration of >10 microg/ml at week 52, whereas 9 (13.8%) of the 65 responders had an infliximab concentration of <1 microg/ml. In the on-demand group, the infliximab concentration at relapse closely correlated with the time to relapse. However, 24 (36.9%) of 65 patients had a resurgence of clinical symptoms at an infliximab concentration of >10 microg/ml, whereas 25 patients (38.4%) had a relapse at an infliximab concentration of <0.5 microg/ml. CONCLUSION: Responsiveness to infliximab treatment is highly heterogeneous among individuals with AS, and this parameter overcomes the circulating infliximab concentration to explain treatment success or failure.
Asunto(s)
Anticuerpos Monoclonales/sangre , Anticuerpos Monoclonales/uso terapéutico , Antirreumáticos/sangre , Antirreumáticos/uso terapéutico , Espondilitis Anquilosante/tratamiento farmacológico , Adulto , Anticuerpos Monoclonales/farmacocinética , Antirreumáticos/farmacocinética , Relación Dosis-Respuesta a Droga , Femenino , Humanos , Infliximab , Masculino , Persona de Mediana Edad , Estudios Prospectivos , Espondilitis Anquilosante/sangre , Resultado del TratamientoRESUMEN
Two [hydroxy(aryl)methylene]diphosphonic acids have been crystallized as dimers. The first compound, [hydroxy(phenyl)methylene]diphosphonic acid monohydrate, C(7)H(10)O(7)P(2).H(2)O, crystallizes in the non-centrosymmetric space group P2(1), with the two enantiomers related by a non-crystallographic centre of inversion, while the second compound, [hydroxy(4-nitrophenyl)methylene]diphosphonic acid tetrahydrofuran disolvate, C(7)H(9)NO(9)P(2).2C(4)H(8)O, crystallizes in the centrosymmetric space group P2(1)/c and uses the centre of symmetry to form the same dimer.