Λεξικό .. Ara h 1

Ara h 1: Peanut allergy is a Type I hypersensitivity (IgE mediated) immune response. Eight peanut allergens have been identified that are termed as Ara h 1 through Ara h 8. The diagnosis of peanut allergy can often be made or eliminated with a focused history and specific diagnostic testing. There is no effective method to cure peanut allergy[1]. Peanut allergy belongs to the group of permanent food allergies with life-threatening character. The major allergen Ara h 1 accumulates a great part of allergenicity of peanut extract.

According to 2D-electrophoresis/immunoblot experiments by means of patient IgE and monoclonal antibodies Ara h 1 consists of at least 16 isoallergens in the pl-range of 4.6 to 8.0 with a mean value of pl 5.9. Ara h 1 exists in isoforms in the range of 63 to 66 kDa and also as dimers with molecular weights of roughly 130 kDa. As shown by ConA reactivity Ara h 1 is a glycoprotein. Testing the occurrence of Ara h 1 in other parts of the peanut plant such as leaves, flowers, roots, developing kernels and germinating kernels without success indicates Ara h 1 as storage protein identified as vicilin by homology screening. Overcoming problems of toxicities of recombinant Ara h 1 in E. coli we were able to clone Ara h 1 which expresses bands with 66 kDa and lower molecular weights.

Probing patients IgE and twelve monoclonal antibodies we find in each group different binding patterns. Interestingly, a pan sensitized patient does not bind to the recombinant allergen but to the natural one reacting with the glyco residue. One monoclonal antibody reacts with the carboxy-terminal portion of Ara h 1 depicting one band. Becker W.-M et al (1997) had the chance to purify recombinant Ara h 1 to homogeneity by affinity chromatography. The estimated molecular weight of the recombinant Ara h 1 is 70.3 kDa. The amino acid sequence identity in comparison to the published one is 96.5%. Now we have the tools to investigate the molecular properties and functions of Ara h 1 in more detail. A reagentless electrochemical impedance biosensor for detection of peanut protein Ara h 1,  has been demonstrated using an Au substrate onto which an antibody film has been immobilized [3].

References

1. Lee LA, Burks AW. New insights into diagnosis and treatment of peanut food allergy. Front Biosci. 2009 Jan 1;14:3361-71.

2. Becker W.-M., Maid B., Buschmann L., Schlaak M. Forschungszentrum Borstel, Division of Allergology, D 23845 Borstel, Germany. The major peanut allergen ara h 1: molecular characterization by 2d-electrophoresis/immunoblot and recombinant techniques. EAACI’97, Rhodos Hellas June 1-5, 1997.

3. Huang Y, Bell MC, Suni II. Impedance biosensor for peanut protein Ara h 1. Anal Chem. 2008 Dec 1;80(23):9157-61.