The copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction is a powerful tool for bioconjugation of biomolecules, particularly proteins and peptides. The major drawback limiting the use of the CuAAC reaction in biological systems is the copper-mediated formation of reactive oxygen species (ROS), leading to the oxidative degradation of proteins or peptides. From the studies on a limited number of proteins and peptides, it is known that, in general, the copper mediated oxidative damage is associated with the copper coordination environment and solvent accessibility. However, there is a lack of data to help estimate the extent of copper-mediated oxidation on a wide range of proteins and peptides. To begin to address this need, we quantitatively measured the degree of copper-mediated oxidation on libraries of 1200 tetrapeptides and a model protein (bovine serum albumin, BSA) using liquid chromatography mass spectrometry (LC-MS). The collected data will be useful to researchers planning to use the CuAAC reaction for bioconjugaton on peptides or proteins.

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Background and PurposeNuclear magnetic resonance (NMR) spectroscopy has become an important technique for tissue studies. Since tissues are in semisolid-state, their high-resolution (HR) spectra cannot be obtained by conventional NMR spectroscopy. Because of this restriction, extraction and high-resolution magic angle spinning (HR MAS) are widely applied for HR NMR spectra of tissues. However, both of the methods are subject to limitations. In this study, the feasibility of HR 1H NMR spectroscopy based on intermolecular multiple-quantum coherence (iMQC) technique is explored using fish muscle, fish eggs, and a whole fish as examples.Materials and MethodsIntact salmon muscle tissues, intact eggs from shishamo smelt and a whole fish (Siamese algae eater) are studied by using conventional 1D one-pulse sequence, Hadamard-encoded iMQC sequence, and HR MAS.ResultsWhen we use the conventional 1D one-pulse sequence, hardly any useful spectral information can be obtained due to the severe field inhomogeneity. By contrast, HR NMR spectra can be obtained in a short period of time by using the Hadamard-encoded iMQC method without shimming. Most signals from fatty acids and small metabolites can be observed. Compared to HR MAS, the iMQC method is non-invasive, but the resolution and the sensitivity of resulting spectra are not as high as those of HR MAS spectra.ConclusionDue to the immunity to field inhomogeneity, the iMQC technique can be a proper supplement to HR MAS, and it provides an alternative for the investigation in cases with field distortions and with samples unsuitable for spinning. The acquisition time of the proposed method is greatly reduced by introduction of the Hadamard-encoded technique, in comparison with that of conventional iMQC method.

Phosphorus metabolism and circulation are essential bio-physicochemical processes during development of a plant and have been extensively studied and known to be affected by temperature, humidity, lighting, hormones etc. However, a quantitative description of how various phosphorous species evolve over time has not been reported. In this work, a combined 31P liquid and solid state NMR spectroscopic methodology is employed, supported by a new extraction scheme and data analysis method, to carry out a quantitative investigation of phosphorous circulation in germinating sesame seeds in dark and under illumination with and without adding a growth hormone. The spectra show that only slight changes occur for phosphorous metabolism at the initial stage but a rapid change takes place between 48–96 hours after germination is started. The metabolism is found to be temperature dependent and affected by illumination and hormone. However, neither illumination nor hormone affects the final residual concentration of phytin. Moreover, phytin does not flow out of cotyledon and the phosphorous flowing to other parts of the plant is always in the inorganic form. The overall evolution profile of phytate consumption is found to be a Gaussian decaying function. These findings can be explained with a dynamic model on phytin conversion.

Consumer choice of milk commonly lacks a scientific basis, and consumers are often unable to obtain the most suitable milk for themselves. As far as know, data profile has not been used to investigate and compare the quality of domestic and foreign milk in Chinese market. Therefore in the current study, we compared the quality of 112 domestic brands and 48 foreign brands using independent samples t-test, correlation analysis, multivariate linear regression analysis, principal component analysis and sensory analysis. In addition, a questionnaire survey was conducted to understand the factors affecting consumers' purchase intention. The results show the contents of protein, calcium and fat in domestic milk were lower than those in foreign milk, whereas domestic milk achieved a higher 50 percentile score in the sensory analysis, but the principal component analysis showed no obvious difference in sensory quality between domestic and foreign milk. The correlation analysis results revealed that the price of domestic milk was strongly positively correlated with protein and fat. Multivariate linear regression analysis showed that protein has significant and positive impact on the price. The questionnaire survey revealed that protein, calcium and fat were the most important nutrients consumers sought to obtain through drinking milk.