Casein is a commonly used protein in the food industry, with its related products such as beverages and desserts. However, the further application of casein is limited by its solubility and stability. This study aimed to improve the functional of casein through protein-glutaminase (PG) deamination. The deamination of casein using PG was optimized through central composite design experiments, and its impact on the structure, solubility, and stability of casein was investigated. The results demonstrate that the optimal conditions for PG deamidation were determined at pH 6.0, E/S 15 U/g, and a temperature of 45 °C. The deamidation process alters the secondary structure of casein, resulting in a decrease in α-helix structure and an increase in β-sheet structure. The modification of casein improved emulsifying activity at pH 8.0 and 10.0, respectively, while significantly enhancing the solubility from 5.0 to 6.0. Furthermore, the deamidation of casein caused an increase in zeta potential and a decrease in particle size, resulting in improved stability of the protein solution due to reduced particle aggregation. The 3% deamidated casein-based beverage with carrageenan exhibited reduced precipitation rates compared to the control after sterilization at 121 °C for 15 min. In summary, PG deamidation offers a promising method for the modification and enhancement of the functional properties, including solubility, stability, and emulsifying activity of casein, thereby expanding its use of casein in the food industry.

Variants in PSEN1, PSEN2, and APP are major genetic causes of early-onset Alzheimer’s disease (EOAD). Our study aimed to identify the genotypic and phenotypic spectrums in a Chinese EOAD cohort and confirm their pathogenicity by functional analysis. This study included 304 unrelated clinically diagnosed EOAD participants of Chinese Han ancestry. Whole-exome sequencing revealed that 26 out of 304 individuals (8.6%) carried rare variants in PSEN1, PSEN2, and APP, including 16 in PSEN1 (5.3%), 6 in PSEN2 (2.0%), and 4 in APP (1.3%). Eight variants were novel, including PSEN1 p.Q56R, PSEN1 p.L174P, PSEN1 p.S289P, PSEN1 p.Y466C, PSEN2 p.R17W, PSEN2 p.F331Y, APP p.D197N, and APP p.D252V. Functional study revealed that the PS1 L174P, S289P, R377M, Y466C, PS2 V214L, and M239T mutants increased Aβ42 levels and Aβ42/Aβ40 ratios. The PS1 L174P, R377M, and Y466C mutants decreased the maturation of presenilin-1. Our findings highlight the prevalence and pathogenic significance of APP /PSENs variants in a Chinese EOAD cohort and expand the phenotypic and genotypic spectrum of EOAD.

Cellular processes depend on Copper(Cu) homeostasis, but overload of Cu in cells leads to the disruption of that balance and induces a specialized model of

Some short-chain fatty acids with a pungent or unpleasant odor are important components of human body odor. These malodors severely threaten human health. The antagonists of malodors would help to improve odor perception by affecting the interaction between odors and their receptors. However, the traditional odor detection and analysis methods, such as MOS, electrochemical, conductive polymer gas sensors, or chromatography-mass spectrometry are not suitable for screening the antagonists since they are unable to detect the ligand efficacy after odor-receptor binding. In this study, RT-PCR results showed that HL-1 cardiomyocytes endogenously express the olfactory receptor 558 (Olfr558) which can be activated by several malodorous short-chain fatty acids. Therefore, an in vitro HL-1 cardiomyocyte-based olfactory biosensor (HCBO-biosensor) was developed by combining cardiomyocytes and microelectrode array (MEA) chips for screening the potential antagonists of the Olfr558. Firstly, it showed that the biosensor specifically responded to ligands of Olfr558 through odor stimulation experiments. Then, an odor response model of HL-1 cardiomyocytes was constructed by a ligand of Olfr558 (isovaleric acid). The response feature of the in vitro HCBO-biosensor to individual odors and mixtures with a potential antagonist (citral or β-damascenone) were extracted and compared. Finally, the Olfr558-inhibited efficiency was indirectly detected by comparing the half-maximal inhibitory concentration of isovaleric acid. The results showed that β-damascenone greatly inhibited Olfr558 while citral showed no significant inhibitory effect. In conclusion, we built a novel screening method for the antagonists of Olfr558 based on HL-1 cardiomyocytes and the MEA chip which will assist odor-related companies to develop novel antagonists of Olfr558.

In cancer cells, higher reactive oxygen species (ROS) than normal cells were observed due to hypermetabolism. The redox balance in cancer cells relies on accordingly upregulated antioxidant capacity. By manipulating oxidation and antioxidant systems, chemotherapeutic drugs can selectively kill cancer cells without hurting normal cells. As three-dimensional (3D) in vitro models, such as spheroids and organoids, have become widely used in cancer research, traditional detection methods (e.g., absorption tests or titration) are inadequate for detecting in 3D environments. Thus, it is crucial to find a new method to detect oxidative stress of 3D in vitro cancer models. Here, a nanocomposite electrochemical biosensor was exploited to evaluate oxidative stress of cancer cells cultured in the 3D environment. The oxidation-regulatory capacity of honokiol, a Magnolia genus-derived anti-cancer molecule, was evaluated. A screen-printed electrode (SPCE) was modified with reduced graphene oxide (RGO) and platinum nanoparticles (Pt NPs) to get Pt NPs/RGO/SPCE. Then the gelatin methacrylate/reduced graphene oxide (GelMA/RGO) hydrogel was applied to immobilized NCI-H1975 in a 3D bionic environment to get NCI-H1975/GelMA/RGO/Pt NPs/RGO/SPCE. After optimizing the experiment condition, the Pt NPs/RGO/SPCE showed a detection threshold of 0.65 μM and a linear field from 1 to 10 μM for H₂O₂ detection while the NCI-H1975/GelMA/RGO/Pt NPs/RGO/SPCE sensitively responded to H₂O₂-induced oxidative stress. By utilizing the NCI-H1975/GelMA/RGO/Pt NPs/RGO/SPCE we found honokiol (a natural polyphenol constituent) inhibits NCI-H1975 by inducing oxidative stress. This simple cell-based electrochemical biosensor can in situ evaluate oxidative stress of 3D cancer models conveniently. It can also be easily extended to the study of the mechanism of action of other drugs and holds broad application prospects in the fields of new drug development and drug repurposing.