αs1-Casein represents one of the major allergens causing cow milk allergy. Few studies have clearly evaluated immunological relationships between IgE- and IgG-binding epitopes of αs1-casein. This study aimed to map IgE- and IgG-binding epitopes of αs1-casein by the serology method, and identify the critical amino acids of αs1-casein by alanine scanning analysis. Our initial data revealed IgE-binding epitopes located in the sequences of AA 126 to 140, AA 6 to 20, AA 171 to 185, and AA 11 to 25. The sequences at AA 21 to 35, AA 56 to 70, and AA 161 to 175 were recognized by IgG antibodies. The alanine scanning analysis showed that IgE- and IgG-binding epitopes share the same critical AA: arginine at position 22 and phenylalanine at position 23. Results obtained from this study will provide necessary information to alter the cDNA to encode a protein with reduced IgE- or IgG-binding capacity.

Rice bran albumin protein (RAP) is sensitive to thermal changes and tends to degrade when exposed to high-temperature processing. In this work, RAP-epigallocatechin-3-gallate (EGCG) complex (RAPE) was prepared and the thermal stability was evaluated. Fluorescence results showed that EGCG could interact with RAP with a binding number n of 0.0885:1 (EGCG:RAP, w/w) and a binding constant K of 1.02 (± 0.002) ×10 /M, suggesting both hydrogen bonding and van der Waals forces played an important role. FTIR analysis demonstrated that EGCG could induce secondary structural changes in RAP above a ratio of 1.6:1 (EGCG:RAP, w/w). Interestingly, the secondary structure changes of RAPE at different temperatures (25, 50, 60, 70, and 80 °C) were inhibited compared with that for RAP, suggesting RAPE was more resistant and stable to the heat treatment. In addition, a dense porous structure of RAPE was achieved due to the EGCG binding after thermal treatment. Furthermore, the T temperature of RAPE increased significantly from 64.58 to 74.16 °C and the enthalpy also increased from 85.53 to 138.52 J/g with a mass ratio increasing from 0 to 3.2 (EGCG:RAP, w/w), demonstrating the thermal stability of RAPE. In addition, the valine, methionine, and lysine content in RAPE were significantly higher than RAP following 80 °C treatment for 20 min (P < 0.05), exhibiting enhanced amino acid profiles, which might be due to EGCG-RAP interactions and microenvironment changes around relevant amino acids. These findings demonstrate that EGCG has the potential to improve the thermal stability of sensitive proteins and is beneficial for usage in the food industry.

An attempt to change the structure of silk fibers and their properties for the biological application was studied by utilizing gamma radiation in various Co60 intensities (0 kGy, 30 kGy, 50 kGy, 100 kGy, 200 kGy, 500 kGy, 1000 kGy, 2000 kGy, 3000 kGy). With the increase of the gamma radiation intensity, SEM result shows that cracks and fragments were formed between microfibrils of the irradiated fiber significantly. Simultaneously SDS-PAGE results give the evidence that the molecular weight of the fibroin diminished. Furthermore, the breaking strength and elongation of irradiated fibers decreased gradually with the increasing Co60 intensity. Although no significant changes of the molecular conformations were found by FTIR and X-ray diffraction, the effects on molecular interactions of the silk fibroin, such as peptide bonding, hydrogen bond and intermolecular bonding force, were obviously observed and enhanced gradually with the increase of gamma radiation intensity.

A block combination genes (gx16-f) was designed and cloned for encoding GX16-F, which was derived from the crystalline domain (X: A, S, V or Y, GA: GAGAGA, GS: GAGAGS, GV: GAGAGV and GY: GAGAGY) and the amorphous domain (F=SGFGPVANGGSGEASSESDFGSSGFGPVANASSGEASSESDFAG) of Bombyx mori silk fibroin heavy chain. The combination genes were then cloned into a GST-tagged prokaryotic expression vector for expression of protein. Agarose gel electrophoresis analysis and DNA sequencing demonstrated that the combination gene encoding GX16-F was accurately cloned, and inserted into the expression vector successfully. The study would provide a technology to produce different structural polypeptides for studying the structurefunction relationships of silk fibroin.

A transformation system was developed for stable germline transformation in the silkworm Bombyx mori L. using piggyBac, a transposon discovered in the lepidopteran Trichoplusia ni, and a helper plasmid. The transposon consists of the piggyBac inverted terminal repeats, the enhanced green fluorescent protein gene as the reporter gene and the spider dragline gene. A nonautonomous helper plasmid encodes the piggyBac transposase. The transformation system was cotransfected into BmN (Bombyx mori L. Nucleopolyhedrovirus) cells using lipofection. PCR amplification on cellular genomic DNA using specific primers showed that a fragment of reporter gene, the spider dragline derived gene and A3 promoter were successfully amplified respectively. Plasmids without being transpositioned were not assayed. Green fluorescence cells were observed at 48 hours after transfection and the fluorescence intensity increased at 72 hours after transfection.