Synthesis of a stable isotopically labeled universal surrogate peptide for use as an internal standard in LC-MS/MS bioanalysis of human IgG and Fc-fusion protein drug candidates

Characterization and determination of bovine immunoglobulin G subtypes in milk and dairy products by UPLC-MS

In this study, ultra-high performance liquid chromatography mass spectrometry (UPLC-MS) method was established for the characterization and quantitative determination of immunoglobulin G (IgG) subtypes (IgG1, IgG2, IgG3) in bovine dairy products. High-resolution mass spectrometry (HRMS) was applied to qualitatively confirm the theoretical peptides with specificity, enzymatic hydrolysis curve and stability among in heavy chain constant (CH1, CH2 and CH3) regions. The characteristic peptides VHNEGLPAPIVR, EPSVFIFPPKPK, GLPAPIVR, VVSALR were screened to quantitative analysis bovine IgG1, IgG2, IgG3 and the total amount of bovine IgG1 and IgG3, respectively. Isotope-labeled peptides were obtained by isotope dimethylation reaction, which aimed to correct the matrix effects. The results showed that the recovery was between 98.7% and 103.5%, and the precision of inter-day and intra-day was less than 6.8%. Moreover, this method had good linearity (R² ≥ 0.999). Therefore, this research provided an effective method for quantitatively detecting bovine IgG subtypes in milk and dairy products.

Ortho-Selective Hydrogen Isotope Exchange of Phenols and Benzyl Alcohols by Mesoionic Carbene-Iridium Catalyst

Hydrogen isotope exchange reactions of phenols and benzyl alcohols have been achieved by a mesoionic carbene-iridium catalyst with high ortho selectivity and high functional group tolerance. Control experiments indicated that acetate is crucial to realize the ortho selectivity, whereas density functional theory calculations supported an outer-sphere direction with hydrogen bonding between acetate and the hydroxyl group.

Rhodium(iii) catalyzed olefination and deuteration of tetrahydrocarbazole

The rhodium-catalyzed olefination and deuteration of tetrahydrocarbazoles in water with the aid of an N,N-dimethylcarbamoyl-protected group is presented. This olefination method features a broad substrate scope, good functional-group tolerance, and high efficiency in water. Practical applications of the protocol are illustrated by the synthesis of various evodiamine derivatives. As such, this environmentally friendly approach to directly modify natural products will attract much attention in academic and industrial research.

Development of an UPLC/MS–MS method for quantification of intact IGF-I from human serum

Aim: Developing LC–MS methods for biomolecules is often challenging due to issues with molecular size and complexity, nonspecific binding, protein binding, solubility and sensitivity. As a result, complex sample preparation workflows, including immune-affinity and/or protein digestion and lengthy analysis potentially using nano-flow LC, may be needed to achieve the required sensitivity. This work aims to provide a simple, sensitive, fast and robust method for quantification of intact IGF-I from human serum using UPLC–MS/MS. Methods: IGF-I serum samples were denatured with sodium dodecyl sulfate, followed by organic protein precipitation to effectively disrupt protein binding and subsequent SPE of the resulting supernatant for sample cleanup and enrichment prior to LC–MS/MS analysis. Separation was performed on an analytical scale LC using a reversed-phase column containing <2 μm solid core particle followed by detection on a tandem quadrupole MS in multiple reaction monitoring mode. Results: Intact IGF-I was quantified from serum using the method described above at a LLOQ of 5 ng/ml with a dynamic range 5–1000 ng/ml (r2>0.99) and mean accuracy of 101.76%. Accuracies for quality control samples were between 93.9–107.7% with RSD <7%. Conclusion: The analytical sensitivity, linear dynamic range and excellent reproducibility of this method reliably measures endogenous and elevated serum IGF-I levels, demonstrating its utility in discovery, bioanalysis and clinical research.

Ruthenium-Catalyzed ortho- and meta-H/D Exchange of Arenes

Ruthenium-catalyzed aromatic H/D exchange in [D₄]acetic acid has been developed. By using N-heteroarenes as directing groups, both ortho and meta positions are selectively deuterated with high levels of D incorporation. Moreover, this strategy provides an alternative way to achieve meta-C-H activation.

Deuterium- and Tritium-Labelled Compounds: Applications in the Life Sciences

Hydrogen isotopes are unique tools for identifying and understanding biological and chemical processes. Hydrogen isotope labelling allows for the traceless and direct incorporation of an additional mass or radioactive tag into an organic molecule with almost no changes in its chemical structure, physical properties, or biological activity. Using deuterium-labelled isotopologues to study the unique mass-spectrometric patterns generated from mixtures of biologically relevant molecules drastically simplifies analysis. Such methods are now providing unprecedented levels of insight in a wide and continuously growing range of applications in the life sciences and beyond. Tritium (³ H), in particular, has seen an increase in utilization, especially in pharmaceutical drug discovery. The efforts and costs associated with the synthesis of labelled compounds are more than compensated for by the enhanced molecular sensitivity during analysis and the high reliability of the data obtained. In this Review, advances in the application of hydrogen isotopes in the life sciences are described.