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Accumulating evidence suggests a correlation between disulfide bonding and the allergenicity of proteins. Also, a significant characteristic of most food allergens is that they are stable to proteases. We sought to identify putative allergens of buckwheat seed comprehensively by combining a disulfide proteome technique with an in vitro digestibility test. First, a dilute acetic acid fraction of buckwheat seed was found to be rich in disulfide proteins. Internal amino acid sequence analyses of these proteins showed that most of them were known allergens or putative allergens sharing high amino acid sequence similarities to known allergens. Next, the fraction was subjected to in vitro protease digestion, which revealed relatively large fragments that were resistant to prolonged enzymatic digestion. These protease‐resistant fragments contained disulfide bonds that should have protected the potential enzyme cleavage sites by forming compact structures. These results confirm and extend our knowledge of the correlations among the disulfide bonding of proteins, their protease stability, and their allergenicity. Also, these observations suggest a new strategy to identify putative allergens by proteomic approaches as well as to mitigate them.

Dihydropyrimidine dehydrogenase (DPD) and pyrimidine nucleoside phosphorylase (PyNPase) are the first and rate-limiting enzymes that regulate 5-fluorouracil (5-FU) metabolism, and tumoral DPD activity appears to be a promising predictor of 5-FU sensitivity. However, the regulatory mechanisms determining these enzyme activities have not been fully understood. We investigated the biological effects of epidermal growth factor (EGF) and transforming growth factor (TGF)-α α α α Key words: Dihydropyrimidine dehydrogenase -Pyrimidine nucleoside phosphorylase -Growth factor -5-Fluorouracil sensitivity -Cervical cancer 5-Fluorouracil (5-FU) has been widely used in the treatment of a variety of neoplastic diseases, particularly cancers of the breast and digestive organs, and is given either alone or in combination with other cytostatics. We have demonstrated that 5-FU-based chemotherapy is also useful for the treatment of uterine cervical cancer.1, 2) Two main modes of action have been proposed for 5-FU through its active metabolites, 5-fluoro-dUMP (FdUMP) and 5-fluoro-UTP. FdUMP suppresses thymidylate synthetase (TS) by forming a covalent ternary complex with 5,10-methylenetetrahydrofolate, which inhibits DNA synthesis.3) 5-Fluoro-UTP is incorporated into cellular RNA, resulting in RNA dysfunction. 4) 5-FU is initially anabolized by pyrimidine nucleoside phosphorylase (PyNPase) in both pathways. Thymidine phosphorylase (ThdPase) converts 5-FU to 5-fluorodeoxyuridine (FUdR), a precursor of FdUMP. Uridine phosphorylase (UrdPase) converts 5-FU to 5-fluorouridine (FUR), a precursor of 5-fluoro-UMP, which is finally metabolized to 5-fluoro-UTP. The former enzyme is identical to platelet-derived endothelial cell growth factor (PD-ECGF) 5) and is closely associated with tumor angiogenesis.5, 6) 5-FU is initially catabolized to 5-fluorodihydrouracil (DHFU) by dihydropyrimidine dehydrogenase (DPD), mainly in the liver, then dihydropyrimidinase and β-ureido-propionase catalyze the formation of 2-fluoro-β-alanine. Several recent studies 7-10) concerned with 5-FU antitumor effects have demonstrated that tumoral DPD activity may influence 5-FU sensitivity. Thus, DPD and PyNPase are considered to be the first and rate-limiting enzymes in the chain of reactions that regulate 5-FU metabolism.Determination of tumoral DPD has become of clinical interest because elevated intratumoral DPD can influence the tumor response to 5-FU therapy as a result of increased inactivation. Etienne et al. 8) evaluated DPD activity in tumor biopsy specimens from head and neck cancer patients before administration of 5-FU and found that the tumoral/non-tumoral DPD activity ratio was higher in the non-responding patients than in those with a partial or complete response. Moreover, certain biochemical modulations to enhance the antitumor activity of 5-FU by inhibiting intratumoral DPD activity have been attempted. 11,12) The underlying differences in tumoral DPD activity result in a variable 5-FU degradation prior to 5-FU

Phthalocyanine (Pc)-dyed fiber is reported to reduce atopic symptoms in some patients when they use underwear made of the fiber. We investigated the adsorption of allergens on Pc-fiber. Pc-fiber trapped house dust/pollen/food allergens with varied molecular weight and pI. The adsorbed allergens were released in the presence of mild detergent. Pc-fiber did not change the molecular weight or disulfide bonding of the allergens. These observations imply that Pc-fiber is applicable as an "allergen trap" for a wide variety of products.