Research on the Structure of Peanut Allergen Protein Ara h1 Based on Aquaphotomics

Peanut allergy is becoming a life-threatening disease that could induce severe allergic reactions in modern society, especially for children. The most promising method applied for deallergization is heating pretreatment. However, the mechanism from the view of spectroscopy has not been illustrated. In this study, near-infrared spectroscopy (NIRS) combined with aquaphotomics was introduced to help us understand the detailed structural changes information during the heating process. First, near-infrared (NIR) spectra of Ara h1 were acquired from 25 to 80°C. Then, aquaphotomics processing tools including principal component analysis (PCA), continuous wavelet transform (CWT), and two-dimensional correlation spectroscopy (2D-COS) were utilized for better understanding the thermodynamic changes, secondary structure, and the hydrogen bond network of Ara h1. The results indicated that about 55°C could be a key temperature, which was the structural change point. During the heating process, the hydrogen bond network was destroyed, free water was increased, and the content of protein secondary structure was changed. Moreover, it could reveal the interaction between the water structure and Ara h1 from the perspective of water molecules, and explain the effect of temperature on the Ara h1 structure and hydrogen-bonding system. Thus, this study described a new way to explore the thermodynamic properties of Ara h1 from the perspective of spectroscopy and laid a theoretical foundation for the application of temperature-desensitized protein products.

Significant Effect of Sample Pretreatment on Ara h1 Extraction and Improved Sensitive SWCNT-Based Detection through Optimization

Single-walled carbon nanotube (SWCNT)-based nanobiosensors have received increasing attention from food researchers as a future instrument of food safety due to their high sensitivity. However, the pretreatment process of the sample applying to SWCNT-based nanobiosensor is required to be more delicate compared to other analyses. In this study, the pretreatment process of Ara h1 protein from its retained complex food matrix was optimized using various buffer compounds and the pretreated allergenic Ara h1 obtained for the optimized process was detected by SWCNT-based nanobiosensor. In the pretreatment process, the buffer extraction method with tris buffer (Tris-HNO3, pH 8.4) was developed and used to extract native peanut allergens from foods. The extraction procedure for Ara h1 from peanut butter foods was performed by varying the temperature, extraction time, and additives (NaCl and skim milk powder). The results of these tests using our SWCNT-based biosensor were analyzed to evaluate the allergenic nature of the extracts. The peak level of Ara h1 extraction was achieved as 84.60 ± 7.50 ng/mL at 21 °C/60 min with the mixture of Tris-HNO3 and 1 M NaCl. In addition, other significant Ara h1 extractions were found to be 29.59 ± 2.57 at 21 °C/15 min and 27.74 ± 1.33 ng/mL at 60 °C/15 min. This study emphasizes the importance of adjusting the extraction time and temperature with respect to the target allergen and food matrix components. After the optimization of the sample pretreatment, the precision of SWCNT-based nanobiosensor by the resistance difference (ΔR) of the SWCNT-based biosensor via linear sweep voltammetry in a potentiostat was identified using the pretreated Ara h1 sample from the processed food compared with the indirect enzyme-linked immunosorbent assay (ELISA) results.

Simultaneous determination of major peanut allergens Ara h1 and Ara h2 in baked foodstuffs based on their signature peptides using ultra-performance liquid chromatography coupled to tandem mass spectrometry

A robust UPLC-MS/MS method was established for the quantitative analysis of the major peanut allergens Ara h1 and Ara h2 in baked foodstuffs based on their signature peptides.

Release of Major Peanut Allergens from Their Matrix under Various pH and Simulated Saliva Conditions—Ara h2 and Ara h6 Are Readily Bio-Accessible

The oral mucosa is the first immune tissue that encounters allergens upon ingestion of food. We hypothesized that the bio-accessibility of allergens at this stage may be a key determinant for sensitization. Light roasted peanut flour was suspended at various pH in buffers mimicking saliva. Protein concentrations and allergens profiles were determined in the supernatants. Peanut protein solubility was poor in the pH range between 3 and 6, while at a low pH (1.5) and at moderately high pHs (>8), it increased. In the pH range of saliva, between 6.5 and 8.5, the allergens Ara h2 and Ara h6 were readily released, whereas Ara h1 and Ara h3 were poorly released. Increasing the pH from 6.5 to 8.5 slightly increased the release of Ara h1 and Ara h3, but the recovery remained low (approximately 20%) compared to that of Ara h2 and Ara h6 (approximately 100% and 65%, respectively). This remarkable difference in the extraction kinetics suggests that Ara h2 and Ara h6 are the first allergens an individual is exposed to upon ingestion of peanut-containing food. We conclude that the peanut allergens Ara h2 and Ara h6 are quickly bio-accessible in the mouth, potentially explaining their extraordinary allergenicity.

Pengaruh Annual Report Award (ARA) terhadap nilai perusahaan

Penelitian ini bertujuan untuk mengetahui pengaruh Annual Report Award (ARA) terhadap nilai perusahaan pada perusahaan yang memenangkan ARA 2013-2015 yang tercatat di Bursa Efek Indonesia. Penelitian ini merupakan penelitian event penelitian selama 11 hari yaitu 5 hari sebelumnya, 1 hari pengumuman, dan 5 hari setelah pengumuman. Nilai perusahaan dalam penelitian ini diukur dengan menggunakan harga saham dan abnormal return. Harga saham yang digunakan adalah harga saham pada saat penutupan. Kembalinya ekspektasi untuk menghitung abnormal return dihitung dengan menggunakan model market adjusted. Teknik pengambilan sampel menggunakan teknik purposive sampling, dan diperoleh sebanyak 15 perusahaan yang memenuhi kriteria sampel. Pengujian hipotesis penelitian ini menggunakan uji deskriptif, uji beda satu sampel t-test, dan paired sample t-test. Hasil pengujian hipotesis menunjukkan bahwa terdapat perbedaan rata - rata harga saham positif dan rata - rata abnormal return positif sebelum dan selama pengumuman ARA (H1 dan H4). Tidak ada perbedaan yang signifikan rata-rata harga saham positif dan abnormal return positif pada dan sesudahnya, serta sebelum dan sesudah pengumuman ARA (H2, H3, H5 dan H6). Dengan demikian penelitian ini menunjukkan bahwa ARA berpengaruh terhadap nilai perusahaan pada saat sebelum dan selama pengumuman saja.