The change in conformation contributed to the decrease in antigenicity of Ara h 2, and the spatial conformation of peanut allergen Ara h 2 plays a critical role in its antigenicity.

Ovalbumin (OVA), one of the major allergens in hen egg white, and has widespread use in experimental models of allergy. The aim of this research was to assess the effect of glycation and heat treatment on the potential allergenicity of OVA prepared from hen egg white. Secondary and tertiary structures of OVA were also characterised to show the relationship between potential allergenicity and the conformation of OVA after heating and glycation. Glycation significantly reduced the potential allergenicity of OVA tested with egg allergy patients' sera, which was caused by conformation changes. An increased IgG reactivity was measured using rabbit anti-OVA and was supposed to be caused by protein unfolding which exposed hidden epitopes. Heating reduced the potential allergenicity of OVA at the expense of increased IgG reactivity. It is suggested that conformational changes of OVA induced by glycation and controlled heating significantly reduced its potential allergenicity.

Two new polyphenol oxidase (PPO) cDNAs (PPO3 and PPO4 cDNAs, accession numbers GQ354801 and GQ354802, respectively) were obtained by RACE-PCR from Agaricus bisporus. PPO3 cDNA was 1844 bp in length with an open reading frame of 1731 bp, while PPO4 cDNA was 2042 bp with an open reading frame of 1836 bp. PPO3 and PPO4 cDNAs, with 52% identity at the nucleic acid level, encoded a 576-amino acid protein of 66.3 kDa and 611-amino acid protein of 68.3 kDa, respectively. Mature forms of PPO3 and PPO4 were characterized after removing the specific C-terminal region and expressed in Escherichia coli BL21 (DE3) RIPL using pGEX-4T-1 vector. The expressed proteins were probed by the anti-A. bisporus PPO antibody but without PPO activity. This indicated that the recombinant mature PPO3 and mature PPO4 could not form an active center in prokaryotic expression system.

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