Proteomics of cypress pollen allergens using double and triple one-dimensional electrophoresis

Italian cypress (Cupressus sempervirens, Cups) pollen causes allergic diseases in inhabitants of many of the cities surrounding the Mediterranean basin. However, allergens of Cups pollen are still poorly known. We introduce here a novel proteomic approach based on double one‐dimensional gel electrophoresis (D1‐DE) as an alternative to the 2‐DE immunoblot, for the specific IgE screening of allergenic proteins from pollen extracts. The sequential one‐dimensional combination of IEF and SDS‐PAGE associated with IgE immunoblotting allows a versatile multiplexed immunochemical analysis of selected groups of allergens by converting a single protein spot into an extended protein band. Moreover, the method appears to be valuable for MS/MS identification, without protein purification, of a new Cups pollen allergen at 43 kDa. D1‐DE immunoblotting revealed that the prevalence of IgE sensitization to this allergen belonging to the polygalacturonase (PG) family was 70% in tested French allergic patients. In subsequent triple one‐dimensional gel electrophoresis, the Cups pollen PG was shown to promote lectin‐based protein‐protein interactions. Therefore, D1‐DE could be used in routine work as a convenient alternative to 2‐DE immunoblotting for the simultaneous screening of allergenic components under identical experimental conditions, thereby saving considerable amounts of sera and allergen extracts.     

On the convexity of the multiplicative potential and penalty functions and related topics

It is well known that a function f of the real variable x is convex if and only if (x,y)→yf(y ^-1 x),y>0 is convex. This is used to derive a recursive proof of the convexity of the multiplicative potential function. In this paper, we obtain a conjugacy formula which gives rise, as a corollary, to a new rule for generating new convex functions from old ones. In particular, it allows to extend the aforementioned property to functions of the form (x,y)→g(y)f(g(y)^-1 x) and provides a new tool for the study of the multiplicative potential and penalty functions. Received: June 3, 1999 / Accepted: September 29, 2000?Published online January 17, 2001     

A convex-analysis perspective on disjunctive cuts

We treat with tools from convex analysis the general problem of cutting planes, separating a point from a (closed convex) set P. Crucial for this is the computation of extreme points in the so-called reverse polar set, introduced by E. Balas in 1979. In the polyhedral case, this enables the computation of cuts that define facets of P. We exhibit three (equivalent) optimization problems to compute such extreme points; one of them corresponds to selecting a specific normalization to generate cuts. We apply the above development to the case where P is (the closed convex hull of) a union, and more particularly a union of polyhedra (case of disjunctive cuts). We conclude with some considerations on the design of efficient cut generators. The paper also contains an appendix, reviewing some fundamental concepts of convex analysis. Supported by NSF grant DMII-0352885, ONR grant N00014-03-1-0188, INRIA grant ODW and IBM.     

Interruptedz-pinch filamentary structure

The longitudinalz-pinch time evolution study between two conical electrodes was carried out by means of the interferometric and the schlieren methods, the discharge basic parameters time development (namely geometry, filamentary structure and electron density) was investigated.     

An Artificial Heme Enzyme for Cyclopropanation Reactions

An artificial heme enzyme was created through self‐assembly from hemin and the lactococcal multidrug resistance regulator (LmrR). The crystal structure shows the heme bound inside the hydrophobic pore of the protein, where it appears inaccessible for substrates. However, good catalytic activity and moderate enantioselectivity was observed in an abiological cyclopropanation reaction. We propose that the dynamic nature of the structure of the LmrR protein is key to the observed activity. This was supported by molecular dynamics simulations, which showed transient formation of opened conformations that allow the binding of substrates and the formation of pre‐catalytic structures.     

Polymerization and copolymerization of 2-phthalimidomethyll 1,3-butadiene. II. Kinetic study of the polymerization of 1,3-butadiene and of the copolymerization of 1,3-butadiene with 2-phthalimidomethyl 1,3-butadiene initiated by bis-(η3-allyl nickel trifluoroacetate)

The kinetics of the polymerization of 1,3-butadiene initiated by bis(η³-allyl nickel trifluoroacetate) prepared in benzene was studied in methylene chloride at 40°C. The reaction is first order with respect to the monomer, second order with respect to the catalyst in contrast to the case in which solvent is benzene. We have shown that the presence of a polar molecule (fe, N-methyl phthalimide) decreases the overall rate of polymerization. The apparent reactivity ratios for the system 2-phthalimidomethyl 1,3-butadiene (1)-1,3-butadiene (2) are r₁ = 0.65 ± 0.006 and r₂ = 0.48 ± 0.015.     

Synthesis of mono and difunctional oligoisobutylenes—III. Modification of α-chlorooligoisobutylene by reaction with maleic anhydride

Reaction of monofunctional oligoisobutylene with maleic anhydride is described. In a preliminary study, thermal dehydrochlorination of α-chlorooligoisobutylene is examined; the double bond of the resulting olefin can be endo or exo. Ene reaction of maleic anhdride with this oligomer is first studied on a model, 2,4,4-trimethyl-1-pentene; resulting mixture is completely analysed by ¹³C- and ¹H-NMR spectroscopy: two isomeric oligomer anhydrides are formed. Ene synthesis is also carried out on α-(2-methyl-2-propenyl)oligoisobutylene; only exo bonds are able to react; the functionality of the resulting oligomeric anhydride mixture is 0.92. In the presence of a catalyst (dichloromaleic anhydride) disubstitution can take place, because the double bond formed in the first reaction is able to react a second time with maleic anhydride.     

Interaction configurations of H2O molecules in a protein (Stratum Corneum) by infrared spectrometry

The procedure previously used to determine the interaction configurations of H₂O molecules in various polysaccharides is applied to a protein: Stratum Corneum (SC). It consists of following by infrared (IR) spectrometry the evaporation, heating and addition of water to a SC membrane. Analyses of the spectra corresponding to these experiments show that even H₂O molecules in equilibrium with the atmosphere are inserted in the protein itself and are held by one hydrogen bond which they accept from an N---H group of the protein and at least one hydrogen bond which they establish (donate) on a C=O group of the protein. At higher concentrations of water, H₂O molecules aggregate and form microdroplets embedded in the protein. Addition of water followed by evaporation of the added H₂O molecules results in an enhancement of the number of hydrogen bonds of type N---HO=C inside the protein. It makes water molecules appear as catalysts to rebuild hydrogen bonds in the protein.     

Chlorine K shell photoabsorption spectra of gas phase HCl and Cl2 molecules

High resolution photoabsorption spectra of HCl and Cl₂ have been measured near the chlorineK edge in the 2810–2850 eV photon energy range. Below the ClK edge, the strongest resonance is interpreted as a simple core excitation into the unoccupied σ* valence orbital for both molecules, leading to a markedly repulsive state. Higher resonances due to low lying Rydberg states, are observed in both systems, but with a larger oscillator strength for HCl as compared to Cl₂. In Cl₂, the σ* orbital is deep enough to avoid any mixing with Rydberg orbitals. In HCl, we observe the dipole forbidden Cl 1s → 4s transition which denotes a strong 4s–4p hybridization. Above the ClK edge, the multiplet features seen for HCl are analysed in terms of double-core-valence excited vacancy states. In Cl₂, their counterpart are found very close to the ionization threshold because of the deep σ* orbital and possibly because the excited core and valence electrons originates either from the same atomic site or from different ones.     

Stepwise Oxidations in a Cofacial Copper(II) Porphyrin Dimer: Through-Space Spin-Coupling and Interplay between Metal and Radical Spins

cis and trans-copper(II) porphyrin dimers have been synthesized, in which two Cu^II porphyrin macrocycles are bridged through a rigid ethene linker for possible through-space and through-bond spin-couplings between the paramagnetic Cu^II centers. It has been found that the two macrocycles come closer after 1 e⁻ oxidation, however, they move far apart upon further 1 e⁻ oxidation leading to transformation of the cis to the trans isomer. Detailed investigations are performed here on the interactions between the two porphyrin macrocycles, between two unpaired spins of closely spaced Cu^II centers, and also between the unpaired spins of metal and porphyrin π–cation radicals. Spectroscopic investigations along with the X-ray structure of the 2 e⁻-oxidized complex displayed strong electronic communications through the bridge between two porphyrin π–cation radicals. The counterion I₉⁻ is stabilized in an unusual trigonal-pyramidal structure in the 2 e⁻-oxidized complex in which the central iodide ion is bound with four iodine (I₂) molecules. Variable-temperature magnetic study revealed strong antiferromagnetic coupling between the two porphyrin π–cation radical spins (J_r–r) in the 2 e⁻-oxidized complex. DFT calculations suggest stabilization of the triplet state, which is also in good agreement with the experiment. Ab initio molecular dynamics allowed the variation of the structural details to be followed upon stepwise oxidations and also the final isomerization process including its associated energy barrier.