Automotive Technology Revolutionized Restorative Dentistry Discovery of Alpha-diketone/Amine Catalyst: Part II -Reflections on Photopolymerization from Conception to Development of Composite Resin and Activator Light.

A full account of the preceded early research tribulation that led to the development of the first visible light activated composite resin and the first visible light activator source is documented. The events took place over four years since early 1974 when a raw industrial composite resin that was radiolucent, stiff paste, universal optically opaque white color, polymerized by exposure to a prototype visible light for 120 seconds was given to developed. Four years later, the developed restorative composite resin ended up as a radiopaque, optically translucent, universal color with an additional three shades that possessed the biologic, esthetic, mechanical and physical characteristics with proven efficacy be used for esthetic zone. This conservative account of early development of a technology that must count as one of a small number of inventions during the seventies, over the years has revolutionized restorative dental practice. We were privileged and very lucky to be associated with developmental stages, stumbling blocks, and final success of the first LC Composite resin that ignited the thought process worldwide and laid the foundation for modern esthetic restoratives practiced today.

Automotive Technology Revolutionized Restorative Dentistry Discovery of Alpha-diketone/Amine Catalyst: Part I.

A full account of early research that led to the discovery of the Alpha-diketone and Amine systems by two Imperial Chemical Industries (ICI) researchers. UK Chemists in the mid-sixties marked the beginning in the early development of a composite resin cured with visible light spectrum into a solid mass. Its incorporation into the newly developed Urethane based resin, led to conceiving the idea of developing the first light-activated restorative composite resin, which formed the prototype of modern composite restorative materials. How all that came about, and the ideas that were conceived and pursued in the development of these systems are discussed in detail.

Measuring bioavailability, utilization, and excretion of rumen-protected lysine in lactating cows using an isotope technique.

Supplementing a diet with rumen-protected amino acids (AAs) is a common feeding strategy for efficient production. For a cost-effective use of rumen-protected AA, the accurate bioavailability of rumen-protected amino acids should be known and their metabolism after absorption needs to be well understood. The current study determined the bioavailability, absorption, utilization, and excretion of rumen-protected Lys (RP-Lys). Four ruminally cannulated cows in a 4 × 4 Latin square design (12 d for diet adaptation; 5 or 6 d for total collections) received the following treatments: L0, a basal diet; L25, the basal diet and L-Lys infused into the abomasum to provide 25.9 g/d L-Lys; L50, the basal diet and L-Lys infused into the abomasum to provide 51.8 g/d L-Lys; and RPL, the basal diet supplemented with 105 g/d (as-is) of RP-Lys to provide 26.7 g of digestible Lys. During the last 5 or 6 d in each period, 15N-Lys (0.38 g/d) was infused into the abomasum for all cows to label the pool of AA, and the total collection of milk, urine, and feces were conducted. 15N enrichment of samples on d 4 and 5 were used to calculate the bioavailability and Lys metabolism. We used a model containing a fast AA turnover (≤ 5 d) and slow AA turnover pool (> 5 d) to calculate fluxes of Lys. The Lys flux to the fast AA turnover pool (absorbed Lys + Lys from the slow AA turnover pool to fast AA turnover pool) was calculated using 15N enrichment of milk Lys. The flux of Lys from the fast AA turnover pool to milk and urine was calculated using 15N transfer into milk and urine. Then, absorbed Lys was estimated by the sum of Lys flux to milk and urine assuming no net utilization of Lys by body tissues. Duodenal Lys flow was estimated by 15N enrichment of fecal Lys. The bioavailability of RP-Lys was calculated from duodenal Lys flows and Lys absorption for RPL. Increasing Lys supply from L25 to L50 increased Lys utilization for milk by 9 g/d but also increased urinary excretion by 10 g/d. For RPL, absorbed Lys was estimated to be 136 g/d where 28 g of absorbed Lys originated from RP-Lys. In conclusion, 68% of bioavailability was obtained for RP-Lys. The Lys provided from RP-Lys was not only utilized for milk protein (48%) but also excreted in urine (20%) after oxidation.

Genome-wide identification of tea plant (Camellia sinensis) BAHD acyltransferases reveals their role in response to herbivorous pests.

BACKGROUND: BAHD acyltransferases are among the largest metabolic protein domain families in the genomes of terrestrial plants and play important roles in plant growth and development, aroma formation, and biotic and abiotic stress responses. Little is known about the BAHDs in the tea plant, a cash crop rich in secondary metabolites. RESULTS: In this study, 112 BAHD genes (CsBAHD01-CsBAHD112) were identified from the tea plant genome, with 85% (98/112) unevenly distributed across the 15 chromosomes. The number of BAHD gene family members has significantly expanded from wild tea plants to the assamica type to the sinensis type. Phylogenetic analysis showed that they could be classified into seven subgroups. Promoter cis-acting element analysis revealed that they contain a large number of light, phytohormones, and stress-responsive elements. Many members displayed tissue-specific expression patterns. CsBAHD05 was expressed at more than 500-fold higher levels in purple tea leaves than in green tea leaves. The genes exhibiting the most significant response to MeJA treatment and feeding by herbivorous pests were primarily concentrated in subgroups 5 and 6. The expression of 23 members of these two subgroups at different time points after feeding by tea green leafhoppers and tea geometrids was examined via qPCR, and the results revealed that the expression of CsBAHD93, CsBAHD94 and CsBAHD95 was significantly induced after the tea plants were subjected to feeding by both pricking and chewing pests. Moreover, based on the transcriptome data for tea plants being fed on by these two pests, a transcriptional regulatory network of different transcription factor genes coexpressed with these 23 members was constructed. CONCLUSIONS: Our study provides new insights into the role of BAHDs in the defense response of tea plants, and will facilitate in-depth studies of the molecular function of BAHDs in resistance to herbivorous pests.

Intramolecular Hydrogen Bonds Assisted Construction of Planar Tricyclic Structures for Insensitive and Highly Thermostable Energetic Materials.

Safety is fundamental for the practical development and application of energetic materials. Three tricyclic energetic compounds, namely, 1,3-di(1H-tetrazol-5-yl)-1H-1,2,4-triazol-5-amine (ATDT), 5'-nitro-3-(1H-tetrazol-5-yl)-2'H-[1,3'-bi(1,2,4-triazol)]-5-amine (ATNT), and 1-(3,4-dinitro-1H-pyrazol-5-yl)-3-(1H-tetrazol-5-yl)-1H-1,2,4-triazol-5-amine (ATDNP), were effectively synthesized through a simple two-step synthetic route. The introduction of intramolecular hydrogen bonds resulted in excellent molecular planarity for the three new compounds. Additionally, they exhibit regular crystal packing, leading to numerous intermolecular hydrogen bonds and π-π interactions. Benefiting from planar tricyclic structural features, ATDT, ATNT, and ATDNP are insensitive (IS > 60 J, FS = 360 N) when exposed to external stimuli. Furthermore, ATNT (Td = 361.1 °C) and ATDNP (Td = 317.0 °C) exhibit high decomposition temperatures and satisfying detonation performance. The intermolecular hydrogen bonding that produced this planar tricyclic molecular structure serves as a model for the creation of innovative multiple heterocycle energetic materials with excellent stability.

Bioinformatic Identification of Signaling Pathways and Hub Genes in Vascular Dementia.

BACKGROUND: Vascular dementia (VaD) is a prevalent neurodegenerative disease characterized by cognitive impairment due to cerebrovascular factors, affecting a significant portion of the aging population and highlighting the critical need to understand specific targets and mechanisms for effective prevention and treatment strategies. We aimed to identify pathways and crucial genes involved in the progression of VaD through bioinformatics analysis and subsequently validate these findings. METHODS: We conducted differential expression analysis, Weighted Gene Co-expression Network Analysis (WGCNA), Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis, and Protein-Protein Interaction (PPI) analysis. We utilized pheochromocytoma 12 (PC12) cells to create an in vitro oxygen-glucose deprivation (OGD) model. We investigated the impact of overexpression and interference of adrenoceptor alpha 1D (ADRA1D) on OGD PC12 cells using TdT-mediated dUTP nick-end labeling (TUNEL), reverse transcription-quantitative polymerase chain reaction (RT-qPCR), western blot (WB), and Fluo-3-pentaacetoxymethyl ester (Fluo-3 AM) analysis. RESULTS: We found 187 differentially expressed genes (DEGs) in the red module that were strongly associated with VaD and were primarily enriched in vasoconstriction, G protein-coupled amine receptor activity, and neuroactive ligand-receptor interaction, mitogen-activated protein kinase (MAPK) signaling pathway, and cell adhesion. Among these pathways, we identified ADRA1D as a gene shared by vasoconstriction, G protein-coupled amine receptor activity, and neuroactive ligand-receptor interaction. The TUNEL assay revealed a significant decrease in PC12 cell apoptosis with ADRA1D overexpression (p < 0.01) and a significant increase in apoptosis upon silencing ADRA1D (p < 0.01). RT-qPCR and WB analysis revealed elevated ADRA1D expression (p < 0.001) and decreased phospholipase C beta (PLCß) and inositol 1,4,5-trisphosphate receptor (IP3R) expression (p < 0.05) with ADRA1D overexpression. Moreover, the Fluo-3 AM assessment indicated significantly lower intracellular Ca2+ levels with ADRA1D overexpression (p < 0.001). Conversely, interference with ADRA1D yielded opposite results. CONCLUSION: Our study provides a new perspective on the pathogenic mechanisms of VaD and potential avenues for therapeutic intervention. The results highlight the role of ADRA1D in modulating cellular responses to OGD and VaD, suggesting its potential as a target for VaD treatment.

Aromatic amine antioxidants (AAs) and p-phenylenediamines-quinones (PPD-Qs) in e-waste recycling industry park: Occupational exposure and liver X receptors (LXRs) disruption potential.

Recently, evidence of aromatic amine antioxidants (AAs) existence in the dust of the electronic waste (e-waste) dismantling area has been exposed. However, there are limited studies investigating occupational exposure and toxicity associated with AAs and their transformation products (p-phenylenediamines-quinones, i.e., PPD-Qs). In this study, 115 dust and 42 hand wipe samples collected from an e-waste recycling industrial park in central China were analyzed for 19 AAs and 6 PPD-Qs. Notably, the median concentration of ∑6PPD-Qs (1,110 ng/g and 1,970 ng/m2) was significantly higher (p < 0.05, Mann-Whitney U test) than that of ∑6PPDs (147 ng/g and 34.0 ng/m2) in dust and hand wipes. Among the detected analytes, 4-phenylaminodiphenylamine quinone (DPPD-Q) (median: 781 ng/g) and 1,4-Bis(2-naphthylamino) benzene quinone (DNPD-Q) (median: 156 ng/g), were particularly prominent, which were first detected in the e-waste dismantling area. Occupational exposure assessments and nuclear receptor interference ability, conducted through estimated daily intake (EDI) and molecular docking analysis, respectively, indicated significant occupational exposure to PPD-Qs and suggested prioritized Liver X receptors (LXRs) disruption potential of PPDs and PPD-Qs. The study provides the first evidence of considerable levels of AAs and PPD-Qs in the e-waste-related hand wipe samples and underscores the importance of assessing occupational exposure and associated toxicity effects.

Insight into chemically reactive metabolites of aliphatic amine pollutants: A de novo prediction strategy and case study of sertraline.

The uncommon metabolic pathways of organic pollutants are easily overlooked, potentially leading to idiosyncratic toxicity. Prediction of their biotransformation associated with the toxic effects is the very purpose that this work focuses, to develop a de novo method to mechanistically predict the reactive toxicity pathways of uncommon metabolites from start aliphatic amine molecules, which employed sertraline triggered by CYP450 enzymes as a model system, as there are growing concerns about the effects on human health posed by antidepressants in the aquatic environment. This de novo prediction strategy combines computational and experimental methods, involving DFT calculations upon sequential growth, in vitro and in vivo assays, dissecting chemically reactive mechanism relevant to toxicity, and rationalizing the fundamental factors. Significantly, desaturation and debenzylation-aromatization as the emerging metabolic pathways of sertraline have been elucidated, with the detection of DNA adducts of oxaziridine metabolite in mice, highlighting the potential reactive toxicity. Molecular orbital analysis supports the reactivity preference for toxicological-relevant C-N desaturation over N-hydroxylation of sertraline, possibly extended to several other aliphatic amines based on the Bell-Evans-Polanyi principle. It was further validated toward some other wide-concerned aliphatic amine pollutants involving atrazine, ε-caprolactam, 6PPD via in silico and in vitro assays, thereby constituting a complete path for de novo prediction from case study to general applications.

Tertiary Amine Coupling by Oxidation for Selective Labeling of Dimethyl Lysine Post-Translational Modifications.

Lysine dimethylation (Kme2) is a crucial post-translational modification (PTM) that regulates biological processes and is implicated in diseases. There is significant interest in globally identifying these methylation marks. Unfortunately, this remains challenging due to the lack of robust technologies for selectively labeling Kme2. To address this, we present a chemical method named tertiary amine coupling by oxidation (TACO). This method selectively modifies Kme2 to aldehydes using Selectfluor and a base. The resulting aldehydes from Kme2 were then functionalized using reductive amination, thiolamine, and oxime chemistry. We successfully demonstrated the versatility of TACO in selectively labeling Kme2 peptides and proteins in complex cell lysate mixtures with varying payloads, including affinity tags and fluorophores. We further showed the application of TACO chemistry for the identification of Kme2 sites at a single-molecule level by fluorosequencing. We discovered novel 30 Kme2 sites, in addition to previously known 5 Kme2 sites, by proteomics analysis of TACO-modified nuclear extracts. Our work establishes a unique strategy for covalently modifying Kme2, facilitating the global identification of low-abundance Kme2-PTMs and their sites within complex cell lysate mixtures.

Roles of Nutrients in the Brain Development, Cognitive Function, and Mood of Dogs and Cats.

The brain is the central commander of all physical activities and the expression of emotions in animals. Its development and cognitive health critically depend on the neural network that consists of neurons, glial cells (namely, non-neuronal cells), and neurotransmitters (communicators between neurons). The latter include proteinogenic amino acids (e.g., L-glutamate, L-aspartate, and glycine) and their metabolites [e.g., γ-aminobutyrate, D-aspartate, D-serine, nitric oxide, carbon monoxide, hydrogen sulfide, and monoamines (e.g., dopamine, norepinephrine, epinephrine, and serotonin)]. In addition, some non-neurotransmitter metabolites of amino acids, such as taurine, creatine, and carnosine, also play important roles in brain development, cognitive health, behavior, and mood of dogs and cats. Much evidence shows that cats require dietary ω3 (α-linolenic acid, eicosapentaenoic acid, and docosahexaenoic acid) and ω6 (linoleic acid and arachidonic acid) polyunsaturated fatty acids for the development of the central nervous system. As an essential component of membranes of neurons and glial cells, cholesterol is also crucial for cognitive development and function. In addition, vitamins and minerals are required for the metabolism of AAs, lipids, and glucose in the nervous system, and also act as antioxidants. Thus, inadequate nutrition will lead to mood disorders. Some amino acids (e.g., arginine, glycine, methionine, serine, taurine, tryptophan, and tyrosine) can help to alleviate behavioral and mood disorders (e.g., depression, anxiety and aggression). As abundant providers of all these functional amino acids and lipids, animal-sourced foods (e.g., liver, intestinal mucosa, and meat) play important roles in brain development, cognitive function, and mood of dogs and cats. This may explain, in part, why dogs and cats prefer to eat visceral organs of their prey. Adequate provision of nutrients in all phases of the life cycle (pregnancy, lactation, postnatal growth, and adulthood) is essential for optimizing neurological health, while preventing cognitive dysfunction and abnormal behavior.

Overcoming the detrimental O-acylation in TMTpro labeling improves the proteome depth and quantification precision.

BACKGROUND: With the advent of proline-based reporter isobaric Tandem Mass Tag (TMTpro) reagents, the sample multiplexing capacity of tandem mass tags (TMTs) has been expanded, and up to 18 samples can be quantified in a multiplexed manner. Like classic TMT reagents, TMTpro reagents contain a tertiary amine group, which markedly enhances their reactivity toward hydroxyl groups and results in O-acylation of serine, threonine and tyrosine residues. This overlabeling significantly compromises proteome analysis in terms of depth and precision. In particular, the reactivity of hydroxyl-containing residues can be dramatically enhanced when coexisting with a histidine in the same peptides, leading to a severe systematic bias against the analysis of these peptides. Although some protocols using a reduced molar excess of TMT under alkaline conditions can alleviate overlabeling of histidine-free peptides to some extent, they have a limited effect on histidyl- and hydroxyl-containing peptides. RESULTS: Here, we report a novel TMTpro labeling method that overcomes detrimental overlabeling while providing high labeling efficiency of amines. Additionally, our method is cost-effective, as it requires only half the amount of TMTpro reagents recommended by the reagent manufacturer. In a deep-scale analysis of a yeast/human two-proteome model sample, we compared our method with a typical alkaline labeling method using a reduced molar excess of TMTpro. Even at a depth of over 10,000 proteins, our method detected 23.7% more unique peptides and 8.7% more protein groups compared to the alkaline labeling method. Moreover, our method significantly improved the quantitative precision due to the reduced variability in labeling and increased protein sequence coverage. This substantially enhanced the statistical power of our method for detecting differentially abundant proteins, providing an average of 13% more yeast proteins that reached statistical significance. SIGNIFCANCE: We presented a novel TMTpro labeling method that overcomes the detrimental O-acylation and thus significantly improves the depth and quantitative precision for proteome analysis.

Insights into Aerosol Emission Control in the Postcombustion CO2 Capture Process: From Cluster Formation to Aerosol Growth.

Aerosols produced in the amine carbon capture process can lead to secondary environmental pollution. This study employs molecular dynamics (MD) simulations to investigate cluster formation, amine behavior, and aerosol growth of amines, essential for reducing amine aerosol emissions. Results showed that the cluster evolution process can be divided into cluster formation and growth in terms of molecular content, and the nucleation rate for the present systems was estimated in the order of 1028 cm-3 s-1. CO2 absorption was observed alongside successful nucleation, with CO2 predominantly localizing in the cluster's outer layer postabsorption. Monoethanolamine (MEA) exhibited robust electrostatic interactions with other components via hydrogen bonding, leading to its migration toward regions where CO2 and H2O coexisted within the cluster. While MEA presence markedly spurred cluster formation, its concentration had a marginal effect on the final cluster size. Elevating water content can augment the aerosol growth rate. However, altering the gas saturation is possible only within narrow confines by introducing vapor. Contrarily, gas cooling introduced dual, opposing effects on aerosol growth. These findings, including diffusion coefficients and growth rates, enhance theoretical frameworks for predicting aerosol formation in absorbers, aiding in mitigating environmental impacts of amine-based carbon capture.

Zero-Emission Cement Plants with Advanced Amine-Based CO2 Capture.

Decarbonization of the cement sector is essentially required to achieve carbon neutrality to combat climate change. Amine-based CO2 capture is a leading and practical technology to deeply remove CO2 from the cement industry, owing to its high retrofittability to existing cement plants and extensive engineering experience in industrial flue gas decarbonization. While research efforts have been made to achieve low-carbon cement with 90% CO2 removal, a net-zero-emission cement plant that will be required for a carbon neutrality society has not yet been investigated. The present study proposed an advanced amine-based CO2 capture system integrated with a cement plant to achieve net-zero CO2 emission by pushing the CO2 capture efficiency to 99.7%. Monoethanomaine (MEA) and piperazine/2-amino-2-methyl-1-propanol (PZ-AMP) amine systems, which are considered to be the first- and second-generation capture agents, respectively, were detailed investigated to deeply decarbonize the cement plant. Compared to MEA, the advanced PZ-AMP system exhibited excellent energy performance with a regeneration duty of ∼2.6 GJ/tonne CO2 at 99.7% capture, 39% lower than the MEA process. This enabled a low CO2 avoided cost of $72.0/tonne CO2, which was 18% lower than that of the MEA-based zero-emission process and even 16.2% lower than the standard 90% MEA process. Sensitivity analysis revealed that the zero-emission capture cost of the PZ-AMP system would be further reduced to below $56/tonne CO2 at a $4/GJ steam production cost, indicating its economic competitiveness among various CO2 capture technologies to achieve a zero-emission cement plant.

Protocol for the preparation of primary amine-containing catalysts on the resin.

In light of escalating sustainability concerns, addressing catalyst usage and waste production challenges becomes crucial. Here, we introduce a robust protocol for crafting recyclable polystyrene-supported primary amines, providing a promising solution via heterogeneous catalysis. The protocol details immobilization onto insoluble resins through ester, ether, or amide bonds, facilitating the synthesis of heterogeneous catalysts with diverse organic components. For complete details on the use and execution of this protocol, please refer to Kanger et al.1.

Role of Carbonyl Compounds for N-Nitrosamine Formation during Nitrosation: Kinetics and Mechanisms.

N-Nitrosamines are potential human carcinogens frequently detected in natural and engineered aquatic systems. This study sheds light on the role of carbonyl compounds in the formation of N-nitrosamines by nitrosation of five secondary amines via different pathways. The results showed that compared to a control system, the presence of formaldehyde enhances the formation of N-nitrosamines by a factor of 5-152 at pH 7, depending on the structure of the secondary amines. Acetaldehyde showed a slight enhancement effect on N-nitrosamine formation, while acetone and benzaldehyde did not promote nitrosation reactions. For neutral and basic conditions, the iminium ion was the dominant intermediate for N-nitrosamine formation, while carbinolamine became the major contributor under acidic conditions. Negative free energy changes (<-19 kcal mol-1) and relatively low activation energies (<18 kcal mol-1) of the reactions of secondary amines with N2O3, iminium ions with nitrite and carbinolamines with N2O3 from quantum chemical computations further support the proposed reaction pathways. This highlights the roles of the iminium ion and carbinolamine in the formation of N-nitrosamines during nitrosation in the presence of carbonyl compounds, especially in the context of industrial wastewater.

Development of a Potential-Modulated Electrochemiluminescence Measurement System for Selective and Sensitive Determination of the Controlled Drug Codeine.

Codeine is a common analgesic drug that is a pro-drug of morphine. It also has a high risk of abuse as a recreational drug because of its extensive distribution as an OTC drug. Therefore, sensitive and selective screening methods for codeine are crucial in forensic analytical chemistry. To date, a commercial analytical kit has not been developed for dedicated codeine determination, and there is a need for an analytical method to quantify codeine in the field. In the present work, potential modulation was combined with electrochemiluminescence (ECL) for sensitive determination of codeine. The potential modulated technique involved applying a signal to electrodes by superimposing an AC potential on the DC potential. When tris(2,2'-bipyridine)ruthenium(II) ([Ru(bpy)3]2+) was used as an ECL emitter, ECL activity was confirmed for codeine. A detailed investigation of the electrochemical reaction mechanism suggested a characteristic ECL reaction mechanism involving electrochemical oxidation of the opioid framework. Besides the usual ECL reaction derived from the amine framework, selective detection of codeine was possible under the measurement conditions, with clear luminescence observed in an acidic solution. The sensitivity of codeine detection by potential modulated-ECL was one order of magnitude higher than that obtained with the conventional potential sweep method. The proposed method was applied to codeine determination in actual prescription medications and OTC drug samples. Codeine was selectively determined from other compounds in medications and showed good linearity with a low detection limit (150 ng mL-1).

Unique fluorescent probe for the recognition of late apoptosis via translocation from plasma membrane to nucleus.

Cell apoptosis is a crucial physiological process playing central roles in key biological and pathological activities. However, the current fluorescent probes for the detection of late apoptosis were "off-on" probes, which were facilely interfered by false positive signals caused by inhomogeneous staining and other factors. Herein, a unique fluorescent probe (NPn) discriminating late apoptosis from early apoptosis and heathy status with two different sets of fluorescent signals have been prepared, to overcome the possible false positive signals. NPn was designed impermeable to biomembranes and simultaneously with high affinity to DNA/RNA, which localized on the plasma membranes of living and early apoptotic cells, while relocated to the nucleus in late apoptotic cells. The hydrophilic amine unit and small ion radius were responsive for its membrane impermeability, which was confirmed with two control molecules without amine group. Using the probe, we have successfully evaluated the cell apoptosis induced by ultraviolet irradiation, rotenone, colchicine, and paclitaxel, demonstrating its potential application in biological researches.

Quantitative Peptidomics Using Reductive Methylation of Amines.

A number of different approaches have been used for quantitative peptidomics. In this protocol, we describe the method in which peptides are reacted with formaldehyde and sodium cyanoborohydride, which converts primary and secondary amines into tertiary amines. By using different combinations of regular reagents, deuterated reagents (2H), and reagents containing deuterium and 13C, it is possible to produce five isotopically distinct forms of the methylated peptides, which can be quantified by mass spectrometry. Peptides with free N-termini that are primary amines incorporate two methyl groups using this procedure, which differ by 2 Da for each of the five isotopic combinations. Peptides that contain unmodified lysine residues incorporate additional pairs of methyl groups, leading to larger mass differences between isotopic forms. The reagents are commercially available, relatively inexpensive, and chemically stable.

Effects of seasoning addition and cooking conditions on the formation of free and protein-bound heterocyclic amines and advanced glycation end products in braised lamb.

The accumulation of heterocyclic amines (HAs) and advanced glycation end products (AGEs) in thermally processed meats has been arising safety concerns. The effects of cooking conditions and seasoning addition on the formation of HAs and AGEs in Chinese traditional braised lamb were investigated by UPLC-MS/MS analysis. Soy sauce significantly increased the formation of HAs and AGEs, among which light soy sauce had the greatest promoting effect (69.45-15300.62 %). Conversely, spices inhibited HAs and AGEs formation, the inhibition rate of free HAs and AGEs reached 22.06-34.72 % when using 70 % ethanol extract. Hot blanching treatment and adding soy sauce and spices at a later stage could significantly suppress HAs and AGEs production. Flavonoids, including galangin, hesperidin, narirutin, etc., were identified as key effectors in spices. These findings help to promote awareness of the formation of HAs and AGEs in braised lamb and provide valuable insights for optimizing processing techniques to minimize their production.