Characterization of the P13 membrane protein of Borrelia burgdorferi by mass spectrometry

Borrelia burgdorferi sensu lato is a tick-borne pathogen that causes Lyme disease. The characterization of membrane proteins from this and other pathogens may yield a better understanding of the mechanisms of infection and information useful for vaccine design. Characterization of the highly hydrophobic Borrelia outer membrane component P13 from a mutant (OspA- OspB- OspC- and OspD-) strain was undertaken by use of a combination of mass spectrometric methods. In a previous investigation, an electrospray ionization (ESI) mass spectrum of the intact protein provided an average molecular weight that was 20 Da lower than the predicted molecular weight. The mass deviation could be explained by a modification of the N-terminus of the protein such as pyroglutamylation (-17 Da) in combination with the experimental error of measurement, however more information was required. New structural information for this membrane protein was provided by peptide mapping with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI TOF MS) and sequencing with ESI-quadrupole-TOF tandem MS.     

The full 2p-h tda and other self-energy approximants: a comparative investigation

A super-operator formulation for decoupling symmetry blocks of the full 2p-h TDA electron propagator matrix is presented, accuracy is explored using the full 2p-h TDA overlap amplitudes to calculate relative ionization intensities for N₂ and H₂O. The effect of excluding orbitais on IPs and relative ionization cross sections is reported.     

Facile Activation of Zinc. Preparation of Cyclobutanones via Dichloroketene and Cyclopropanes Using the Simmons-Smith Reaction

Zinc powder activated by heating in an inert atmosphere gave good yields when used for the title reactions. The very easy work up procedure for the cyclobutanones further increases the potential of the method.     

A Facile Formal Synthesis of Volicitin

A short and concise synthesis of volicitin is presented. The synthesis is based on repeated chemoselective copper salt cross coupling reactions of alkynes and propargylic halides.     

Fabrication process parameters significantly affect the perovskite oxygen carriers materials (OCM) performance in chemical looping with oxygen uncoupling (CLOU)

Journal of Thermal Analysis and Calorimetry - The CLOU performance of the CaTixMn0.9?xMg0.1O3 (CMTM) perovskite-type system was investigated, comparing materials produced at laboratory scale...     

Synthetic efforts towards the protoilludenes. A formal synthesis of Δ-protoilludene

An improved route to 5,8,8-trimethylbicyclo[4.3.0]-4-nonen-3-one, a key intermediate for the synthesis of the protoilludane skeleton and in particular Δ⁷-protoilludene, is reported. Attempts on an alternative synthesis of Δ⁶-protoilludene based on a phenylsulfonyl allene cycloaddition reaction is also presented.     

Bond making and bond breaking in molecular dynamics

The theoretical concept of a potential energy surface, so important for the accepted pictures of molecular structure and bonding, plays a key role in most current methods of molecular reaction dynamics. However, the lack of quality potential energy surfaces for anything but the smallest of systems and the great expense and difficulty in producing several surfaces and their nonadiabatic coupling terms with sufficient accuracy is becoming a hindrance to accurate reaction dynamics. The electron nuclear dynamics (END) theory provides a new way to address this problem by circumventing the use of potential energy surfaces while accounting fully for nonadiabatic couplings. Preliminary results for the prototypical low-energy reactive collision between the hydrogen molecular ion and the hydrogen molecule are given for both electron transfer and chemical exchange. © 1996 John Wiley & Sons, Inc.     

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