Capillary isoelectric focusing in pseudo-closed channel coupled to matrix assisted laser desorption/ionization mass spectrometry for protein analysis

Capillary isoelectric focusing (CIEF) was performed in pseudo-closed channel to separate proteins on a plastic chip. Pseudo-closed channel provided a novel way to couple protein separation by CIEF to MALDI mass spectrometry without eluting the focused proteins.     

Formation of ordered arrays of oriented polyaniline nanoparticle nanorods

We report the preparation of ordered polyaniline (PANI) nanorod arrays in an aqueous medium. The oriented PANI nanorods (80-400 nm in diameter and 8-15 mum in length) were synthesized in the presence of hydrophilic Allura Red AC (ARAC) as the structure-directing agent and ammonium persulfate as an oxidant in HCl solution. The morphologies of the oriented PANI nanoparticle nanorods were confirmed by scanning electron microscopy (SEM) and transmission electron microscopy images, and the effect of reaction conditions on the morphology of PANI nanostructures was also studied. On the basis of the result obtained from small-angle X-ray scattering, we propose that rodlike micelle arrays of ARAC-aniline are responsible for directing the formation of oriented PANI nanoparticle nanorods. SEM images and the data analysis of static and dynamic light scattering give supportive evidence to the formation of the PANI nanoparticle nanorods by an elongation process. The chemical and electronic structures of the PANI nanorods were also studied by Fourier transform IR and UV-vis spectrometries, respectively.     

Regiospecificity in the synthesis of diaryl sulfones

The addition of arylsulfinic acids to 2-methyl-1,4-benzoquinone provides high yields of sulfones in a wide variety of solvents. The distribution of isomeric products obtained is strongly influenced by either (1) the acidity of aqueous solvents or (2) the water content of alcohol solvents. The distribution of isomeric products does not change in the various anhydrous, aprotic solvents examined.     

Oxidation of propylene by palladium chloride in acetic acid

Conclusions The oxidation of propylene by palladium chloride in glacial acetic acid leads to the formation of isopropenyl acetate, cis-n-propenyl acetate, trans-n-propenyl acetate, the corresponding alkylidene diacetate, and small amounts of allyl acetate.Translated from Izvestiya Akademii Nauk SSSR, Khimicheskaya, No. 12, pp. 2204–2206, December, 1965     

Measurement of Colloidal Stability in Solutions of Simple, Nonadsorbing Polyelectrolytes

The stability of a solution of charged polystyrene particles in the presence of nonadsorbing polyelectrolyte macromolecules is measured using optical light scattering. The particles were negatively charged polystyrene latex spheres (0.5–1 μm diameter) while the macromolecules were simulated using negatively charged colloidal silica spheres (5–7 nm diameter). Because of the electrostatic repulsion between the particles, the solution is found to be stable against primary flocculation (irreversible flocculation into a primary energy minima). However, because of long-range attractive depletion forces, reversible secondary flocculation of the particles occurs into a local potential energy minimum. As observed with uncharged macromolecules, the polyelectrolyte first induces flocculation at a critical flocculation concentration (v*), but later restabilizes the system at a critical restabilization concentration (v**). These critical concentrations are found to decrease with decreasing macromolecule size and increasing particle size. The restabilized solutions are found to remain suspended for periods greater than 20 days. Comparison of the measured flocculation and restabilization results to predictions made using a recently developed force-balance model show qualitative agreement.     

Anomalin,a new natural pyranocoumarin

Summary A new coumarin C₂₄H₂₆O₇, which we have calledanomalin has been isolated from the roots ofAngelica anomala Avé-Lall. On the basis of its chemical properties, the results of a study of its saponification products and UV, IR, and NMR spectroscopy it has been established that anomalin is 2,2-dlmethyl-3,4-diangeloyl-3,4-dihydropyrano-5,6: 8, 7-cournarin.     

The Reaction of SnCl2 with the Complexes cis-PtCl2 (phosphorus ligand)2 as studied by 31P and 195Pt NMR

The reactions of SnCl₂ with the complexes cis-PtCl₂P₂, P=trialkyl and triaryl phosphines and phosphites, in CDCl₃ and CD₂Cl₂ have been studied using ³¹P and ¹⁹⁵Pt NMR. methods. For equimolar amounts of Sn and Pt, products of the type PtCl(SnCl₃)P₂ are formed with the complex geometry depending on the nature of P. For P?PEt₃ and P(OPh)₃, further addition of SnCl₂ produces trans-Pt(SnCl₃)₂ complexes. The syntheses of trans-PtCl(SnCl₃) (PEt₃)₂ and trans-Pt(SnCl₃)₂ (OPh₃)₂ are described.     

Top down characterization of secreted proteins from Mycobacterium tuberculosis by electron capture dissociation mass spectrometry

Secreted proteins of Mycobacterium tuberculosis are implicated in its disease pathogenesis and so are considered as potential diagnostic and vaccine candidates. The search for these has been slow, even though the entire genome sequence of M. tuberculosis is now available; of the 620 protein spots resolved by 2-D gel electrophoresis, 114 secreted proteins have been identified, but for only 13 has the primary structure been partly characterized. For comparison, in this top down mass spectrometry (MS) approach the secreted proteins were precipitated from cell culture filtrate, resuspended, and examined directly by electrospray ionization (ESI) Fourier transform MS. The ESI spectra of three precipitates showed 93, 535, and 369 molecular weight (M(r)) values, for a total of 689 different values. However, only approximately 10% of these values matched (+/-1 Da) the DNA predicted M(r) values, but these identifications were unreliable. Of nine molecular ions characterized by MS/MS, only one protein match was confirmed, and its isotopic molecular ions were overlapped by those of another protein. MS/MS identified a total of ten proteins by sequence tag search, of which three were unidentified previously. The low success of M(r) matching was due to unusually extensive posttranslational modifications, including loss of a signal sequence, loss of the N-terminal residue, proteolytic degradation, oxidation, and glycosylation. Although in eubacteria the latter is relatively rare, a 9 kDa protein showed 7 hexose attachments and two 20 kDa proteins each had 20 attachments. For MS/MS, electron capture dissociation was especially effective.