SummaryBackground: Little is known on the clinical relevance of peanut 2S albumin Ara h 7.

Summary Background Screening for specific IgE against 2S albumin proteins Ara h 2 and 6 has good positive predictive value in diagnosing peanut allergy. From the third 2S member Ara h 7, 3 isoforms have been identified. Their allergenicity has not been elucidated. Objective This study investigated the allergenicity of Ara h 7 isoforms compared to Ara h 2 and 6. Methods Sensitization of 15 DBPCFC‐confirmed peanut‐allergic patients to recombinant Ara h 2.0201, Ara h 6.01 and isoforms of recombinant Ara h 7 was determined by IgE immunoblotting strips. A basophil activation test (BAT) was performed in 9 patients to determine IgE‐cross‐linking capacities of the allergens. Sensitivity to the allergens was tested in 5 patients who were sensitized to at least 1 Ara h 7 isoform, by a concentration range in the BAT. 3D prediction models and sequence alignments were used to visualize differences between isoforms and to predict allergenic epitope regions. Results Sensitization to Ara h 7.0201 was most frequent (80%) and showed to be equally potent as Ara h 2.0201 and 6.01 in inducing basophil degranulation. Sensitization to Ara h 7.0201 together with Ara h 2.0201 and/or 6.01 was observed, indicating the presence of unique epitopes compared to the other 2 isoforms. Differences between the 3 Ara h 7 isoforms were observed in C‐terminal cysteine residues, pepsin and trypsin cleavage sites and 3 single amino acid substitutions. Conclusion & clinical relevance The majority of peanut‐allergic patients are sensitized to isoform Ara h 7.0201, which is functionally as active as Ara h 2.0201 and 6.01. Unique epitopes are most likely located in the C‐terminus or an allergenic loop region which is a known allergenic epitope region for Ara h 2.0201 and 6.01. Due to its unique epitopes and allergenicity, it is an interesting candidate to improve the diagnostic accuracy for peanut allergy.

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Klebsiella pneumoniae, Azotobacter vinelandii and Rhodobacter capsulatus were cultivated in media containing "MOO$-. The distribution of "Mo in cells grown under conditions of repression and derepression of nitrogenase synthesis, was investigated by anion-exchange (DEAE-Sephacel) chromatography, Cells of K. pneumoniae took up MOO:-only under conditions of derepression of nitrogenase thus serving the formation of the FeMo cofactor of the MoFe protein (Kpl) as the predominant Mo-containing species. In the case of A. vinelandii, under diazotrophic growth conditions, molybdenum was preferably incorporated into the nitrogenase MoFe protein (Avl). However, if excess amounts of molybdate were present in the medium, molybdenum was also bound to the Mo-storage protein. In the presence of 20 mM NH,', conditions which completely repress nitrogenase formation, molybdenum accumulated in the Mo-storage protein exclusively. This protein proved to be unstable towards DEAE-Sephacel, apparently releasing all the molybdenum in form of MOO:-during the fractionation procedure. R. capsulatus contained, in addition to the MoFe protein (Rcl), significant amounts of other not-yet-identified Mo species, which partially are formed under conditions of both, repression and derepression of nitrogenase.The Mo centers of all these compounds were characterized by measuring the nuclear quadrupole interaction of the process "Mo(P-)"Tc using time differential perturbed angular correlation spectroscopy. Keywords: nitrogenase ; molybdenum-iron protein ; molybdenum-storage protein; time differential perturbed angular correlation (TDPAC) spectroscopy.The biological nitrogen fixation is one of the most important processes in nature, because it is essential for the N-cycle and thus for the life of all organisms (for reviews see [l-31). The conventional nitrogenase enzyme system responsible for the reduction of molecular N, to NHf consists of two separable proteins, the MoFe protein (component 1) and the Fe protein (com- whose primary role is the mediation of electrons in nitrogenase, and (b) the iron-molybdenum cofactor (FeMo cofactor, FeMoco), which is located in the a-subunits and has been postulated to be the active site for substrate (e.g. N,) reduction. Based on X-ray structure analyses of MoFe proteins from Azotobacter vinelandii and Clostridium pasteurianum, a structural cofactor model has recently been published [6, 71. According to this model the FeMo cofactor consists of two cubane fragments (Fe,S, and MoFe,S,) bridged by three inorganic sulfide ligands. The Mo center is ligated by two 0 atoms from homocitrate and one N atom from histidine of the protein side chain. In this work we determined the nuclear quadrupole interacprotein and in other Mo-containing proteins present in different (TDPAC) spectroscopy Of y-rays. This method detects the hyperfine interaction between the nuclear quadruPole moment of the probe nucleus (in our case 9 9 M~) and an electric field gradient (EFG). Since the EFG depends on the distribution tion (NQI) parameters of...

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