Supramolecular Complexation of \u3cem\u3eN\u3c/em\u3e-Alkyl- and \u3cem\u3eN\u3c/em\u3e,\u3cem\u3eN\u3c/em\u3e′-Dialkylpiperazines with Cucurbit[6]uril in Aqueous Solution and in the Solid State

Water seeds: Complex stoichiometry/composition and degree of oligomerization (oligomeric supramolecular complex formation) of cucurbit[6]uril (CB[6]) with N-alkyl- and N,N′-dialkylpiperazine were investigated in aqueous solutions by means of isothermal titration calorimetry (ITC), ESI-MS, NMR and light scattering measurements. Complex stoichiometry/composition and degree of oligomerization (oligomeric supramolecular complex formation) of cucurbit[6]uril (CB[6]) with N-alkyl- and N,N′-dialkylpiperazine were investigated in aqueous solutions by means of isothermal titration calorimetry (ITC), ESI-MS, NMR and light scattering measurements. It was found that the complex stability and the degree of oligomerization increase with elongating the alkyl chain attached to the piperazine core. X-ray crystallographic studies revealed a clear correlation between the structure of CB[6]–alkylpiperazine crystals obtained from aqueous solutions and the molecular weight/properties of host–guest oligomers existed in the solution as supramolecular “seeds” of crystal formation

Probing metal ion binding and conformational properties of the colicin E9 endonuclease by electrospray ionization time-of-flight mass spectrometry

Nano-electrospray ionization time-of-flight mass spectrometry (ESI-MS) was used to study the conformational consequences of metal ion binding to the colicin E9 endonuclease (E9 DNase) by taking advantage of the unique capability of ESI-MS to allow simultaneous assessment of conformational heterogeneity and metal ion binding. Alterations of charge state distributions on metal ion binding/release were correlated with spectral changes observed in far- and near-UV circular dichroism (CD) and intrinsic tryptophan fluorescence. In addition, hydrogen/deuterium (H/D) exchange experiments were used to probe structural integrity. The present study shows that ESI-MS is sensitive to changes of the thermodynamic stability of E9 DNase as a result of metal ion binding/release in a manner consistent with that deduced from proteolysis and calorimetric experiments. Interestingly, acid-induced release of the metal ion from the E9 DNase causes dramatic conformational instability associated with a loss of fixed tertiary structure, but secondary structure is retained. Furthermore, ESI-MS enabled the direct observation of the noncovalent protein complex of E9 DNase bound to its cognate immunity protein Im9 in the presence and absence of Zn2+. Gas-phase dissociation experiments of the deuterium-labeled binary and ternary complexes revealed that metal ion binding, not Im9, results in a dramatic exchange protection of E9 DNase in the complex. In addition, our metal ion binding studies and gas-phase dissociation experiments of the ternary E9 DNase-Zn2+-Im9 complex have provided further evidence that electrostatic interactions govern the gas phase ion stability

Kinetic study of an on-chip isocyanate derivatization reaction by on-line nano-esi ms

A high-throughput method is presented for the study of reaction kinetics by nano- electrospray ionization mass spectrometry (nano-ESI MS). The reaction of propyl isocyanate (2), benzyl isocyanate (3), and toluene-2,4-diisocyanate (4) with 4-nitro-7- piperazino-2,1,3-benzoxadiazole (NBDPZ) (1) to yield the corresponding urea derivatives (5) was carried out in a continuous flow glass microchip. Real-time monitoring of the reactions was done by nano-ESI MS. Rate constants of 1.6 ␣ 104 M-1 min-1, 5.2 ␣ 104 M-1 min-1, and 2.5 ␣ 104 M-1 min-1 were determined for isocyanate 2, 3 and 4, respectively

Monitoring of beta-Blockers Ozone Degradation via Electrospray Ionization Mass Spectrometry

Santos, LS (reprint author), Talca Univ, Lab Asymmetr Synth, POB 747, Talca, Chile.The structures of intermediate products of ozone degradation of different pharmaceutical compounds have been studied. Under the conditions employed, complete ozone degradation of nadolol was achieved after 100 min. The degradation products obtained in aqueous solution were characterized by electrospray ionization mass (and tandem mass) spectrometry (ESI-MS and ESI-MS/MS). The proposed mechanism for degradation, ozone attacks at the aniline amino group giving rise to nitro compounds and further degradation occurs via a series of oxidative processes. Continuous online monitoring by ESI-MS(/MS) with high accuracy mass measurements showed that ozone degradation of atenolol (ATE) and acebutolol (ACE) occurs via mechanisms similar to that of nadolo

Identifikasi Etiologi Diare Akut pada Anak dengan Teknologi Gabungan Reaksi Rantai Polimerase dan Spektrometri Massa di Rumah Sakit Penyakit Infeksi Prof. Dr. Sulianti Saroso

PCR–electrospray ionization mass spectrometry (PCR-ESI/MS), suatu peralatan baru yang mampu mendeteksi hampir semua mikroorganisme patogen, namun belum pernah digunakan di Indonesia. Tujuan penelitian ini untuk memperoleh pengalaman dengan PCR/ESI-MS dan panel food borne pathogen, mengetahui kelebihan dan kelemahan teknologi ini. Rancangan penelitian potong lintang, menggunakan spesimen dari poliklinik anak, dilakukan dari bulan juli 2012 hingga desember 2012, dan akhirnya 24 spesimen diperiksa dengan PCR/ESI-MS. Karakteristik diare terdiri dari 12 dengan lendir, 3 diare berdarah dan 20 hanya diare cair saja. Pada sebagian besar kasus dijumpai lebih dari satu bakteri. Bakteri E. coli FDA29 ditemukan pada kasus disertai demam dan sakit Perut, namun tidak ada pada kasus tanpa kelainan tersebut. Jenis bakteri dengan PCR/ESI-MS berbeda dengan kultur. Metoda ini dapat mendeteksi bakteri dalam waktu 24 jam dan sangat bermanfaat pada wabah. Berdasarkan kemampuan metoda ini untuk mendeteksi beberapa bakteri dari satu spesimen, tampaknya biayanya tidak lebih mahal dibanding kultur. Metoda ini sangat bermanfaat untuk surveilans dalam hal menemukan kesamaaan antara penyebab penyakit dan pejamu. PCR–electrospray ionization mass spectrometry (PCR-ESI/MS), a new equipment that can detect almost all human patogenic microorganism, but never used before in Indonesia.The aim of this study to get experience with PCR/ESI-MS and panel food borne pathogen, to know the profile of bacteria that caused diarhea by PCR/ESI-MS, and know the advantage and handicapped of this equipment.Study design was descriptive cross sectional, using specimen from Child ambulatory clinic, was done from July 2012 until December 2012 and finally 24 was examined with PCR/ESI-MS. Clinical characteristic consist of fever 9 (37,5%), vomiting 17 (70.8%)and abdominal pain 11 (45.8%). Mayority (75%) got diarhea from 3-5 daily. Characteristic of diarhea, 12 cases with mucus, 3 cases bloody diarhea and 20 cases only liquid faeces. In most cases, we found multiple bacteria . Bacteria E. coli FDA29 was detected on cases with fever and abdominal pain but not found in cases without those manifestation. Type of bacteria in this study was different with cultur result. This method can detect bacteria in 24 hours, and very useful in outbreak, and if we calculate the cost and the ability of this metod to detect several bacteria from single specimen, it seems nearly the same. It seems that this method will be very useful for surveilans ie to find similarity between agent and host

Structural Plasticity and Noncovalent Substrate Binding in the GroEL Apical Domain. A study using electrospray ionization mass spectrometry and fluorescence binding studies

Advances in understanding how GroEL binds to non-native proteins are reported. Conformational flexibility in the GroEL apical domain, which could account for the variety of substrates that GroEL binds, is illustrated by comparison of several independent crystallographic structures of apical domain constructs that show conformational plasticity in helices H and I. Additionally, ESI-MS indicates that apical domain constructs have co-populated conformations at neutral pH. To assess the ability of different apical domain conformers to bind co-chaperone and substrate, model peptides corresponding to the mobile loop of GroES and to helix D from rhodanese were studied. Analysis of apical domain-peptide complexes by ESI-MS indicates that only the folded or partially folded apical domain conformations form complexes that survive gas phase conditions. Fluorescence binding studies show that the apical domain can fully bind both peptides independently. No competition for binding was observed, suggesting the peptides have distinct apical domain-binding sites. Blocking the GroES-apical domain-binding site in GroEL rendered the chaperonin inactive in binding GroES and in assisting the folding of denatured rhodanese, but still capable of binding non-native proteins, supporting the conclusion that GroES and substrate proteins have, at least partially, distinct binding sites even in the intact GroEL tetradecamer

Numerical modeling of capillary electrophoresis : electrospray mass spectrometry interface design

Capillary electrophoresis hyphenated with electrospray mass spectrometry (CE-ESI-MS) has emerged in the past decade as one of the most powerful bioanalytical techniques. As the sensitivity and efficiency of new CE-ESI-MS interface designs are continuously improving, numerical modeling can play important role during their development. In this review, different aspects of computer modeling and simulation of CE-ESI-MS interfaces are comprehensively discussed. Relevant essentials of hydrodynamics as well as state-of-the-art modeling techniques are critically evaluated. Sheath liquid-, sheathless-, and liquid-junction interfaces are reviewed from the viewpoint of multidisciplinary numerical modeling along with details of single and multiphase models together with electric field mediated flows, electrohydrodynamics, and free fluid-surface methods. Practical examples are given to help non-specialists to understand the basic principles and applications. Finally, alternative approaches like air amplifiers are also included

Using mass spectrometry techniques for the elucidation of structural features of immunostimulatory polysaccharides from medicinal plantsaqueous extracts

Polysaccharides are well known for their immunostimulatory properties, which are closely related to structural fèatures, such as molecular weight, branching, acetylation degree and acetylation pattem, and presence of speciflc structures [1, 2]. TTie electrospray ionization-mass spectrometry (ESI-MS) and electrospray ionization tandem mass spectrometry (ESI-MS/MS) have shown to be powerfül techniques that can provide detailed information regarding the structural features of polysaccharides and help to clarify its relation to some ofthe observed immunostimulatory properties [3-6]. TTie present work desenhes the use of ESI-MS and ESI-MS/MS in the confimation and elucidation of structural features of immunostimulatory polysaccharides present in lhe aqueous extracts of Fraxinus angustifolia dned leaws and Ptemapaitum tridentatum dried inflorescences. The polysaccharides present in the aqueous extracts of F. angustifolia dried leaves and P. fridentafum dried inflorescences were isolated and fractionated using dialysis, ethanol precipitation, and anionexchange chromatography. Sugar and linkage analysis suggested that the aqueous extracts of F. angustifolia were mostly composed of pectic polysaccharides, while those from P. tridentatum contained a mixture of pectic polysacchahdes, galactomannans, and also xyloglucans. Selected fractions isolated from lhe aqueous extracts of F. angustifolia and P. tridentatum evidenced an in vitro macrophage immunostimulatory activity, expressed through the production of nitric oxide (NO). Enzymatic hydrolysis of the isolated polysaccharides, fbllowed by size exclusion chromatography of the resulting oligosaccharides (OS), and ESI-MS and ESI-MS/MS characterization allowed to confirm the presence of pectic polysaccharides, possibly with xylogalaturonan domains, in the aqueous extracts of F. angustifolia. For the aqueous extracts of P. fridentatum it was possible to detect the presence of galactomannans acetylated at 0-2. Moreover, it was possible to identify acetylated OS that presented an acetylation pattem with much more acetyl groups than those observed for galactomannans from coffee infusions [3]. The saponification ofthe fraction isolated from the aqueous extracts of P. tridentatum dried inflorescences, which contained the acetylated galactomannans, caused a decrease in the NO macrophage production, confirming lhe galactomannans acetylation as an important structural feature for lhe expression of the in vitm macrophage immunostimulatory activity previously registered.info:eu-repo/semantics/publishedVersio

The Composition of Arylstibonic Acids

This thesis describes a detailed ESI-MS investigation into the arylstibonic acids, organo-antimony-containing compounds that are currently of interest as anticancer reagents. Four arylstibonic acids, of nominal formula RC6H4SbO3H2 [R = p-chloro-, p-tolyl-, p-nitro- and α-naphthyl-] were synthesised, and a further eight archival samples from the National Cancer Institute Repository were obtained for use in the project. Results indicate clearly that the acids exist as polyoxometalate aggregates [H8(RSb)12O28], rather than monomeric species, in both the solid state and in acetonitrile solution, thus resolving a century-old debate concerning the nature of their molecular composition. Variations in solvent, time in solution and pH have also defined the stability of these aggregates under different conditions. Synthesis of arylstibonic acids by traditional methods (pre-1940) has been shown to lead to products contaminated with cations present during their preparation. An improved method of synthesis has been devised, and the crystal structure of an intermediate in the synthesis of these acids, [C6NH6][p-O2NC6H4SbCl5], is reported. Salts of arylstibonic acids with a range of cations were investigated by ESI-MS and shown to form a diverse family of polyoxostibonates with nuclearities including Sb12, Sb14 and Sb16. Crystal structures containing some of these aggregates, verified through parallel studies with collaborators, are described. Preliminary study of mixed polyoxometalates (Sb/As) showed a strong tendency to form As4Sb2 species but these could not be fully characterised