The Effect of Acidic Residues on the Binding between Opicalcin1 and Ryanodine Receptor from the Structure-Functional Analysis.

Calcin is a group ligand with high affinity and specificity for the ryanodine receptors (RyRs). Little is known about the effect of its acidic residues on the spacial structure as well as the interaction with RyRs. We screened the opicalcin1 acidic mutants and investigated the effect of mutation on activity. The results indicated that all acidic mutants maintained the structural features, but their surface charge distribution underwent significant changes. Molecular docking and dynamics simulations were used to analyze the interaction between opicalcin1 mutants and RyRs, which demonstrated that all opicalcin1 mutants effectively bound to the channel domain of RyR1. This stable binding induced a pronounced asymmetry in the structure of the RyR tetramer, exhibiting a high degree of structural dissimilarity. [3H]Ryanodine binding to RyR1 was enhanced in D2A and D15A, which was similar to opicalcin1, but that effect was suppressed in E12A and E29A and reversed for the DE-4A, thereby inhibiting ryanodine binding. Opicalcin1 and DE-4A also exhibited the ability to form stable docking structures with RyR2. Acidic residues play a crucial role in the structure of calcin and its functional interaction with RyRs that is beneficial for the calcin optimization to develop more active peptide lead compounds for RyR-related diseases.

Building a predictive model for hypertension related to environmental chemicals using machine learning.

Hypertension is a chronic cardiovascular disease characterized by elevated blood pressure that can lead to a number of complications. There is evidence that the numerous environmental substances to which humans are exposed facilitate the emergence of diseases. In this work, we sought to investigate the relationship between exposure to environmental contaminants and hypertension as well as the predictive value of such exposures. The National Health and Nutrition Survey (NHANES) provided us with the information we needed (2005-2012). A total of 4492 participants were included in our study, and we incorporated more common environmental chemicals and covariates by feature selection followed by regularized network analysis. Then, we applied various machine learning (ML) methods, such as extreme gradient boosting (XGBoost), random forest classifier (RF), logistic regression (LR), multilayer perceptron (MLP), and support vector machine (SVM), to predict hypertension by chemical exposure. Finally, SHapley Additive exPlanations (SHAP) were further applied to interpret the features. After the initial feature screening, we included a total of 29 variables (including 21 chemicals) for ML. The areas under the curve (AUCs) of the five ML models XGBoost, RF, LR, MLP, and SVM were 0.729, 0.723, 0.721, 0.730, and 0.731, respectively. Butylparaben (BUP), propylparaben (PPB), and 9-hydroxyfluorene (P17) were the three factors in the prediction model with the highest SHAP values. Comparing five ML models, we found that environmental exposure may play an important role in hypertension. The assessment of important chemical exposure parameters lays the groundwork for more targeted therapies, and the optimized ML models are likely to predict hypertension.

Rhenium Suppresses Iridium (IV) Oxide Crystallization and Enables Efficient, Stable Electrochemical Water Oxidation.

IrO2 as benchmark electrocatalyst for acidic oxygen evolution reaction (OER) suffers from its low activity and poor stability. Modulating the coordination environment of IrO2 by chemical doping is a methodology to suppress Ir dissolution and tailor adsorption behavior of active oxygen intermediates on interfacial Ir sites. Herein, the Re-doped IrO2 with low crystallinity is rationally designed as highly active and robust electrocatalysts for acidic OER. Theoretical calculations suggest that the similar ionic sizes of Ir and Re impart large spontaneous substitution energy and successfully incorporate Re into the IrO2 lattice. Re-doped IrO2 exhibits a much larger migration energy from IrO2 surface (0.96 eV) than other dopants (Ni, Cu, and Zn), indicating strong confinement of Re within the IrO2 lattice for suppressing Ir dissolution. The optimal catalysts (Re: 10 at%) exhibit a low overpotential of 255 mV at 10 mA cm-2 and a high stability of 170 h for acidic OER. The comprehensive mechanism investigations demonstrate that the unique structural arrangement of the Ir active sites with Re-dopant imparts high performance of catalysts by minimizing Ir dissolution, facilitating *OH adsorption and *OOH deprotonation, and lowering kinetic barrier during OER. This study provides a methodology for designing highly-performed catalysts for energy conversion.

IrO2-Stablized La2IrO6 perovskite nanotubes via corner-shared interconnections as highly-efficient oxygen evolution electrocatalysts.

One-dimensional nanotube heterostructures with IrO2-stabilized La2IrO6 is obtained by an electrospinning approach. The La2IrO6/IrO2 catalyst exhibits superior catalytic activity and strong stability for the oxygen evolution reaction. The synergistic cooperation between the two types of Ir as the active sites in La2IrO6/IrO2 is demonstrated by in situ Raman spectrum and DFT calculation.

Colorimetric detection of alkaline phosphatase activity based on pyridoxal phosphate-induced chromatic switch of polydiacetylene nano-liposomes.

A colorimetric assay based on polydiacetylenes (PDA) nano-liposomes is reported for facile and sensitive detection of alkaline phosphatase (ALP) activity. The critical basis of this method is that the interaction of pyridoxal phosphate (PLP) with nitrogenous group functionalized PDA nano-liposomes induces distinct blue-to-red color changes of PDA nano-liposomes. In the presence of ALP, as a nature substrate, PLP is enzymatically hydrolyzed to form pyridoxal, which cannot interact with PDA nano-liposomes. As a result, the concentration of PLP is reduced and the color change of PDA nano-liposomes is retarded, which is associated with ALP level. Under optimal conditions, the proposed method showed good linear relationship with ALP activity in the range 10-200 U/L with a limit of detection of 2.8 U/L. The detection process could be vividly observed with the naked eye. Additional attempts by using the method for the evaluation of inhibitor efficiency were also achieved with satisfying results. The method was further challenged with real human serum samples, showing consistent results when compared with a commercial standard assay kit. Such simple and easy-to-use approach may provide a new alternative for clinical and biological detection of ALP.

NaBH4-reduction induced tunable oxygen vacancies in LaNiO2.7 to enhance the oxygen evolution reaction.

Tunable oxygen vacancies of LaNiO3 (LNO-Vo) are realized by theoretical prediction and the NaBH4-reduction approach. The LNO2.7 catalyst exhibits superior catalytic activity and long-term stability for water oxidation. Direct evidence of the active site center and the intermediates is observed from in situ Raman spectra and DFT calculations.

Label-free liquid crystal immunosensor for detection of HBD-2.

A label-free liquid crystal (LC) immosensorsensor based on the orientation changes of LC was developed for the detection of HBD-2 (human ß-defensin-2) through competitive immunoassay. HBD-2 was tethered onto the semassembled film surface on a glass slide via a cross-linker glutaradehyde. The DMOAP/APTES/GA (N,N-dimethyl-N-octadecyl (3-aminopropyl) trimethoxysilyl chloride/(3-aminopropyl) trimethoxysilane/glutaraldehyde) mixed self-assembled monolayers formed by both long and short alkyls could cause vertical alignment uniformly of liquid crystal. The specific binding of anti-HBD-2 antibody and HBD-2 induced the homeotropic-to-tilted transition of liquid crystal, making a visible optical change observed under the crossed polarized light and achieving the detection of HBD-2. The average gray-scale intensity of optical appearances has a good linear relationship with the concentration of HBD-2 when the concentration of HBD-2 is in the range of 1-10 ng mL-1 and the linear correlation coefficient is 0.9956. The limit of quantification is 0.53 ng mL-1 for the HBD-2. This study offers a simple, highly sensitive and specific, label -free method for HBD-2 detection.