Identification of the interface of a large protein-protein complex using H/D exchange and Fourier transform ion cyclotron resonance mass spectrometry

An infrared multiphoton dissociation (IRMPD) spectrum, obtained by Fourier transform ion cyclotron resonance mass spectrometry (FTICRMS), was used to dissociate and to identify fragment ions from recombinant human interleukin-6 (IL-6; 21 KDa). The entire sequence was assigned by a single IRMPD experiment, and the observed fragment ions reflected the IL-6 secondary structure. This method was combined with H/D off-exchange to identify IL-6 and anti-human IL-6 mouse monoclonal antibody MH166 (150-kDa) binding sites in the IL-6 molecule. To facilitate the data analysis, the protein complex formation and the hydrogen exchange were performed with an immobilized antibody. Quenching of the hydrogen exchange reaction and collection of the deuterated IL-6 were performed by elution under acidic conditions to measure the mass spectrum directly. IL-6 was dissociated by using IRMPD, and the interface of IL-6 bound to anti-IL-6 antibody MH166 was determined to analyze the deuterium incorporation level of each fragment ion. Thus, two discontinuous regions, Leu 126-Lys 131 and Asp 160-Met 184, were identified as the antibody binding sites. These regions are adjacent to each other on the tertiary structures determined by NMR and X-ray analyses.     

Synthesis of 2,3-disubstituted indole using palladium(II)-catalyzed cyclization with alkenylation reaction

The reaction of ethyl 2-ethynylphenylcarbamate derivative with alkenes in the presence of a palladium(II) catalyst, copper dichloride and tetrabutylammonium fluoride (TBAF) produced 2-substituted 3-ethenylindoles during refluxing. The intramolecular cyclization reaction of ethyl 2-ethynylphenylcarbamates, which have an ethenyl part in the ethynyl group, was also used to produce carbazole derivatives.     

The total absolute curvature of an equiaffine immersion

For an equiaffine immersion of general codimension, we recently defined the Lipschitz-Killing curvature, where we fix a transversal bundle and a transversal volume element. The main purpose of this paper is to show that the integration of the absolute value of the Lipschitz-Killing curvature is independent of the choices of a transversal bundle and a transversal volume element.     

Ion pair catalysis of the autooxidation of pyridine and benzil in emulsion systems

It was found that the rates of absorption of oxygen by pyridine–aqueous sodium hydroxide emulsions and the same emulsions containing benzil were catalyzed by the addition of quaternary salts and followed the same rate law: . It was concluded that the autooxidation of benzil in pyridine-aqeuous sodium hydroxide emulsions has as its rate-determining step a step in the autooxidation of pyridine. Possibly the superoxide formed in the autooxidation of pyridine is the oxidizing agent in the oxidation of benzil.     

Exact results for the diluted Ising model with competing interactions

We consider the random-bond Ising model with the exchange integrals J > 0, ?J and 0 with the respective probabilities p, q and r, where p + q + r = 1. We give the exact value of the averaged internal energy and an exact upper bound to the averaged specific heat at temperature T determined by $\text{k}{}_{\mathrm{B}}\text{T =}\text{2J}\text{In[}\text{p}\text{(1 ? p ? r)}\text{]}\text{,}$ where k_B is the Boltsmann constant. We show that all the averaged correlation functions of even spins are non-negative at this temperature.     

Adaptive optics fundus camera using a liquid crystal phase modulator

We have developed an adaptive optics (AO) fundus camera to obtain high resolution retinal images of eyes. We use a liquid crystal phase modulator to compensate the aberrations of the eye for better resolution and better contrast in the images. The liquid crystal phase modulator has a wider dynamic range to compensate aberrations than most mechanical deformable mirrors and its linear phase generation makes it easy to follow eye movements. The wavefront aberration was measured in real time with a sampling rate of 10 Hz and the closed loop system was operated at around 2 Hz. We developed software tools to align consecutively obtained images. From our experiments with three eyes, the aberrations of normal eyes were reduced to less than 0.1 μm (RMS) in less than three seconds by the liquid crystal phase modulator. We confirmed that this method was adequate for measuring eyes with large aberrations including keratoconic eyes. Finally, using the liquid crystal phase modulator, high resolution images of retinas could be obtained.