Incorporation Of Methyl Groups Research Articles

Synthesis, crystallization behavior and mechanical property of biodegradable Poly(butylene succinate-co-2-methyl succinate) copolyesters

In this research, a series of biodegradable poly(butylene succinate-co-2-methyl succinate) (PBSMS) random copolyesters with butylene 2-methyl succinate (BMS) unit content from about 10 to 90 mol% were successfully synthesized. Both the homopolymers poly(butylene succinate) (PBS), poly(butylene 2-methyl succinate) (PBMS), and PBSMS copolyesters showed relatively high intrinsic viscosity values of over 0.8 dL/g. The basic thermal parameters, crystallization behavior, crystal structure, spherulitic morphology and growth rate, and mechanical properties of PBSMS copolyesters were extensively studied and compared with those of PBS. The incorporation of methyl group not only effectively increased the toughness of PBSMS copolyesters but also significantly restrained the crystallizability of these copolyesters, showing that PBSMS copolyesters with the BMS unit content higher than 50 mol% were amorphous. Among these copolyesters, PBSMS30 (BMS unit content = 30 mol%) exhibited the most outstanding mechanical properties, with a Young's modulus of 188.0 ± 19.1 MPa, a tensile strength of 19.1 ± 1.8 MPa, and an elongation at break of 714.5 ± 23.2 %. By randomly introducing methyl as a side group into the PBS main chain, the mechanical properties of PBSMS copolyesters have been significantly improved. From the perspective of structure and properties, this study should be interesting and crucial for the development and research of biodegradable polymers.

Thiopyran-Fused Mono and Double Helicenes with Low Band Gaps via Simultaneous Ring Expansion and 6-endo Cyclizations.

Mono and double helicenes (M5, M6, D5, and D6) containing six-membered thiopyran rings have been successfully prepared via simultaneous ring expansion and 6-endo cycloisomerizations from the corresponding precursors with five-membered thiophene rings. Although D5 and D6 exhibit similar chemical structures, they demonstrate completely different helical structures because of their distinct steric clashes caused by the incorporated methyl groups. Moreover, all of the thiopyran-fused helicenes exhibit broad absorption bands covering the visible and near-infrared regions.

Development and characterization of cranberry pomace extract incorporated and vitamin E fortified edible films as an edible separation sheet for fruit leather.

The separation sheets for fruit leather are traditionally made of plastic film or wax paper, which not only leads to environmental issues but also is inconvenience to consumers. This study evaluated edible fruit leather separation sheets using food polymers, including hydroxypropyl methyl cellulose (HPMC) and incorporation of cranberry pomace water extract (CPE) for providing natural fruit pigment, flavor, and phenolics. HPMCCPE film was then further improved by incorporating hydrophobic compound (oleic acid, OA) and vitamin E (VE) via cellulose nanocrystal (CNC) Pickering emulsion (CNCP) for enhancing film hydrophobicity and nutritional benefit, respectively. The CNCP-HPMCCPE film exhibited reduced water vapor permeability (∼0.033gmm/m2dPa) compared to HPMCCPE film (∼0.59gmm/m2dPa) and had the least change in mass and moisture content when wrapping fruit leather for up to 2 weeks of ambient storage. The fruit leather wrapped by CNCP-HPMCCPE film showed lower weight change than those by films without CNCP due to low mass transfer between film and fruit leather. CNCP resulted in controlled release of VE into a food simulating solvent (ethanol). The developed colorful and edible fruit leather separation sheet satisfied the increased market demands on sustainable food packaging. PRACTICAL APPLICATION: Colorful and flavorful edible films made of edible polymers, fruit pomace water extract, and emulsified hydrophobic compounds with vitamin E were created. The films have the satisfactory performance to replace the conventional fruit leather separation sheet made of plastic or wax paper. The edible films can be eaten with packaged fruit leather for not only reducing packaging waste but also providing convenience and nutritional benefit to consumers. These functional edible films may also be utilized to package other food products for promoting packaging sustainability and nutritional benefit.

High C2H6/C2H4 selectivity via incorporation of dense methyl groups into a stable Zr-based MOF with cavity-like pores

The development of efficient adsorbents for C2H6/C2H4 separation is an important and challenging issue for the economical production of high-purity ethylene, a valuable precursor for the petrochemical industry. We developed an efficient adsorbent for C2H6/C2H4 separation by incorporating highly dense methyl groups into a highly stable UiO-66 framework with “cavity-like” pores. Remarkably, UiO-66-2Me exhibited large C2H6 uptake at 1 bar (2.15 mmol/g) and significantly high C2H6/C2H4 IAST selectivity (2.93), which is one of the highest values reported. From a combined experiments and computational study, we verified that the observed high selectivity was originated from the specific interaction between C2H6 and multiple methyl groups in the cavity-like pores. Moreover, UiO-66-2Me showed high C2H6/C2H4 selectivity (2.05) even under the dynamic mixture flow condition, easy regeneration and good hydrothermal and thermal stabilities. These results suggest that incorporating highly dense methyl groups into a stable MOF with cavity-like pores is a promising method for developing an efficient adsorbent for C2H6/C2H4 separation.

Conversion of the CG specific M.MpeI DNA methyltransferase into an enzyme predominantly methylating CCA and CCC sites.

We used structure guided mutagenesis and directed enzyme evolution to alter the specificity of the CG specific bacterial DNA (cytosine-5) methyltransferase M.MpeI. Methylation specificity of the M.MpeI variants was characterized by digestions with methylation sensitive restriction enzymes and by measuring incorporation of tritiated methyl groups into double-stranded oligonucleotides containing single CC, CG, CA or CT sites. Site specific mutagenesis steps designed to disrupt the specific contacts between the enzyme and the non-substrate base pair of the target sequence (5'-CG/5'-CG) yielded M.MpeI variants with varying levels of CG specific and increasing levels of CA and CC specific MTase activity. Subsequent random mutagenesis of the target recognizing domain coupled with selection for non-CG specific methylation yielded a variant, which predominantly methylates CC dinucleotides, has very low activity on CG and CA sites, and no activity on CT sites. This M.MpeI variant contains a one amino acid deletion (ΔA323) and three substitutions (N324G, R326G and E305N) in the target recognition domain. The mutant enzyme has very strong preference for A and C in the 3' flanking position making it a CCA and CCC specific DNA methyltransferase.

Formation of plant resistance to pathogens involving epigenetic factors and phytohormones

The development of resistance to plant pathogens is determined by the presence of resistance genes and regulation of their activity due to phytohormones, the activity of the nuclear pore complex, and epigenetic modifications at the post-transcriptional and post-translational levels of DNA and histones, respectively. Changes in gene expression due to such modifications can be inherited in generations and contribute to the selection of resistant plants in populations.The nuclear pore complex is composed of nucleoporins, a nuclear pore basket, cytoplasmic filaments and is able to selectively transport transcription factors to the nucleus from the cytoplasm and mRNA in the opposite direction, affecting gene expression. Methylation is the most common and well-studied among the epigenetic modifications. It is described for DNA and histones and ensures genome stability and the availability of transcription factors. Incorporation of methyl groups to amino acid residues is not always a factor in gene silencing for histones. The number of the incorporated groups as well as an amino acid they are attached to are crucial. Histone acetylation is associated with the transition to transcriptional activity.The general control histone acetyltransferase TaGCN5 is able to promote expression of the enoyl-CoA reductase gene in allohexaploid wheat, which is involved in the biosynthesis of cuticular wax as one of the resistance factors. The reverse process of deacetylation acts both as a positive regulator, through ethylene response factors, and a negative one, as it interferes with acetylation and methylation of histone amino acids. Jasmonic and salicylic acids, along with combinations of the mentioned phytohormones, mediate formation of systemic acquired resistance in addition to ethylene. Auxin is a positive phytohormone for pathogens due to its ability to influence the structure of the cell wall. At the same time, pathogens, due to effectors, are able to inhibit the plant’s immune responses, so there is a constant “arms race” resulting in the selection of more effective means of penetration and development in the plant as well as its protective reactions. Investigation of the mechanisms of resistance formation and identifying the main factors of resistance, such as either presence of a gene sequence and/or factors regulating its expression, are of great importance.

Boron-Doped Methylated Amorphous Silicon for Negative Electrodes in Li-Ion Batteries

In spite of its outstanding capacity for alloying with lithium, silicon cannot be practically used as a negative electrode for Li-ion batteries: its large volume expansion upon lithiation leads to a poor capacity retention [1]. Promising results have been obtained by incorporating methyl groups in amorphous silicon (methylated amorphous silicon). This material exhibits an improved stability upon electrochemical cycling while keeping a capacity close to that of pure silicon [2]. However, the conductivity of methylated amorphous silicon may be a strong limitation, especially at high methyl content: for example, 10% methylated amorphous silicon is 10000 more resistive than pure amorphous silicon.Doping is a well-known method to enhance the electronic conductivity of semiconductors, even if the dopant activity is lower in amorphous semiconductors than in crystalline ones. 2% boron doping increases the conductivity of 10% methylated amorphous silicon by five orders of magnitude compared to the undoped material.Boron doped methylated silicon thin films (100nm thick) with various methyl content were cycled in the range 0.025V – 1V at C/2 rate (electrolyte: LP30 with 5%FEC). 10% methylated amorphous silicon with 2% boron doping exhibits a capacity retention of 70% after 500 cycles of full lithiation/delithiation, an improved performance as compared to the undoped material (see Figure 1a). Interestingly, boron doping allows for using higher methyl content without demanding pre-conditioning procedures for the electrochemical cycling of the material. The stability upon cycling is found to be further increased for 15% and 20% methylated electrodes, with a capacity retention exceeding 80% over 1000 cycles of full lithiation/delithiation (Figure 1b). This figure comes at the expense of a decreased total capacity (which remains 3 to 4 times larger than that of the current carbon electrodes). The SEI evolution and structural changes are currently investigated using operando ATR FTIR and ex-situ Raman spectroscopies, in order to rationalize the factors limiting the Coulombic efficiency to 99.7%.

73‐3: Student Paper: Achieving Deep‐Blue Color in Diboron Embedded Multi‐Resonance Thermally Activated Delayed‐Fluorescence Emitter for Narrowband OLEDs

We report three deep blue multiple resonant TADF emitters, m‐ν‐DABNA, 4F‐ν‐DABNA, and 4F‐m‐ν‐DABNA by incorporating methyl groups and fluorine atoms in diboron based ν‐DABNA core. The introduction of methyl groups and fluorine atoms resulted in bandgap enhancement by electron donating and electron withdrawing effects. All three emitter's exhibit pure blue emissions with high photoluminescence quantum yield around ~90%, small ΔEST (≤ 0.07 eV) values, and fast reverse intersystem crossing rate (kRISC). Fabricated OLEDs with these emitters show excellent external quantum efficiency over 33%. Among three materials, 4F‐ν‐DABNA and 4F‐m‐ν‐DABNA exhibit the CIE y coordinate of 0.08 and 0.06, respectively.

The Amount of Dietary Methionine Required to Maximize Synthesis of Transmethylated Products Is Higher Than That Needed for Protein Synthesis in Neonatal Piglets

ObjectivesMethionine is an indispensable sulfur-containing amino acid required for synthesizing protein as well as other critical nutrients. Methionine is the primary methyl donor for >50 transmethylation reactions to produce metabolites including creatine, phosphatidylcholine (PC), and methylated DNA. In piglets, because only one-third of methionine flux is incorporated into protein compared to transmethylation reactions (∼2/3), non-protein demands need to be considered when determining methionine requirement. Our objective was to quantify how much dietary methionine is required to maximize synthesis of protein as well as key transmethylated products. We hypothesized that more dietary methionine will be needed to maximize creatine synthesis, with lower levels required to maximize PC and protein synthesis. MethodsTwenty surgically altered Yucatan miniature piglets (∼8 d old; ∼1.6 kg) were fed complete diets for 5 d and then randomized to 20 test diets with methionine intakes ranging from 20%-220% of requirement (0.05–0.55 g/kg/d). After 24 h of test diet, [3H-methyl]-methionine was infused for 6 h to measure methyl incorporation into creatine, PC, and methylated DNA, and then a3H-phenylalanine flooding dose was given to measure protein synthesis. Break-point analysis was used to identify the methionine required to maximize product synthesis. ResultsPlasma methionine increased above 0.3 g methionine/kg/d, reflecting the whole body requirement. Creatine synthesis maximized at ∼0.3 g methionine/kg/d, while muscle protein synthesis was maximized at 0.2 g methionine/kg/d, suggesting growth is prioritized when methionine is limiting. PC synthesis was low up to 0.35 g methionine/kg/d and increased linearly with higher intakes, suggesting PC synthesis was not maximized at 200% of requirement.3H-DNA did not change with dietary methionine, and plasma homocysteine was positively correlated with dietary methionine. ConclusionsThese data suggest that more methionine is required to accommodate demands for creatine and PC synthesis than that for protein synthesis. Therefore, methionine requirement estimates for infants, which rely on protein synthesis outcomes, are likely insufficient to achieve maximal synthesis of key methylated metabolites creatine and PC. Funding SourcesNSERC.

Deep blue diboron embedded multi-resonance thermally activated delayed fluorescence emitters for narrowband organic light emitting diodes

• Newly synthesized diboron embedded deep blue MR-TADF emitters. • Narrow spectra with FWHM of 14 nm and CIE y coordinate below 0.10. • Small △E ST (≤0.07 eV), high PLQY, and good TADF performances. • All these materials show high EQEs (>33%) We report three deep blue multiple resonant TADF emitters, m-ν-DABNA, 4F-ν-DABNA, and 4F-m-ν-DABNA by incorporating methyl groups and fluorine atoms in diboron based ν-DABNA core. The introduction of methyl groups at para positions to the boron atoms and fluorine atoms at ortho positions to the nitrogen atoms resulted in bandgap enhancement by electron donating and electron withdawing effects. All three emitters exhibit pure blue emissions with high photoluminescence quantum yield around ∼ 90%, small ΔE ST (≤0.07 eV) values, and fast reverse intersystem crossing rate (k RISC ). Fabricated OLEDs with these emitters show excellent external quantum efficiency over 33%. Among three materials, 4F-ν-DABNA and 4F-m-ν-DABNA exhibit the CIE y coordinate of 0.08 and 0.06, respectively. Our current material design approach guides a path for the development of deep blue TADF emitters for highly efficient narrowband OLEDs.

Exploring Electrochemical C(sp3)-H Oxidation for the Late-Stage Methylation of Complex Molecules.

The "magic methyl" effect, a dramatic boost in the potency of biologically active compounds from the incorporation of a single methyl group, provides a simple yet powerful strategy employed by medicinal chemists in the drug discovery process. Despite significant advances, methodologies that enable the selective C(sp3)-H methylation of structurally complex medicinal agents remain very limited. In this work, we disclose a modular, efficient, and selective strategy for the α-methylation of protected amines (i.e., amides, carbamates, and sulfonamides) by means of electrochemical oxidation. Mechanistic analysis guided our development of an improved electrochemical protocol on the basis of the classic Shono oxidation reaction, which features broad reaction scope, high functional group compatibility, and operational simplicity. Importantly, this reaction system is amenable to the late-stage functionalization of complex targets containing basic nitrogen groups that are prevalent in medicinally active agents. When combined with organozinc-mediated C-C bond formation, our protocol enabled the direct methylation of a myriad of amine derivatives including those that have previously been explored for the "magic methyl" effect. This synthesis strategy thus circumvents multistep de novo synthesis that is currently necessary to access such compounds and has the potential to accelerate drug discovery efforts.

Detection and Quantification of Histone Methyltransferase Activity In Vitro.

Histone methyltransferases (HMTs) catalyze the methylation of lysine and arginine residues in histone as well as nonhistone substrates. In vitro histone methyltransferase assays have been instrumental in identifying HMTs, and they continue to be invaluable tools for the study of these important enzymes, revealing novel substrates and modes of regulation.Here we describe a universal protocol to examine HMT activity in vitro that can be adapted to a range of HMTs, substrates, and experimental objectives. We provide protocols for the detection of activity based on incorporation of 3H-labeled methyl groups from S-adenosylmethionine (SAM), methylation-specific antibodies, and quantification of the reaction product S-adenosylhomocysteine (SAH).

Antibacterial properties of polyaniline derivatives

AbstractThis work presents a detailed study on the effect of various functional groups both at the ortho position of the aromatic ring and in the amino group of PANI on the antibacterial properties of polymers against gram‐positive (Bacillus subtilis) and gram‐negative (Pseudomonas aureofaciens) microorganisms. It was found that incorporation of methyl, methoxy, or pentyl groups into the ortho‐position of PANI did not increase the antibacterial activity but in most cases causes a significant decrease in the antibacterial properties of functionally substituted polyanilines. At the same time, PANI derivatives modified by incorporation of pentyl groups into the amino group were found to be more efficient antibacterial compounds against both gram‐positive and gram‐negative microorganisms than the original polymer. It was also found that N‐substituted PANI derivatives manifest not only bactericidal but also bacteriostatic properties toward the test microorganisms. Varying the nature and position of the substituent allowed us to conclude that the synthesis of various N‐substituted PANI derivatives with a high degree of doping is the most promising approach to PANI modification for application in bacterial growth inhibition.

Synthesis, Microstructure, and Properties of High-Molar-Mass Polyglycolide Copolymers with Isolated Methyl Defects.

An efficient, fast, and reliable method for the synthesis of high-molar-mass polyglycolide (PGA) in bulk using bismuth (III) subsalicylate through ring-opening transesterification polymerization is described. The difference between the crystallization (Tc ≈ 180 °C)/degradation (Td ≈ 245 °C) temperatures and the melting temperature (Tm ≈ 222 °C) significantly affects the ability to melt-process PGA homopolymer. To expand these windows, the effect of copolymer microstructure differences through incorporation of methyl groups in pairs using lactide or isolated using methyl glycolide (≤10% methyl) as comonomers on the thermal, mechanical, and barrier properties were studied. Structures of copolymers were characterized by nuclear magnetic resonance (1H and 13C NMR) spectroscopies. Films of copolymers were obtained, and the microstructural and physical properties were analyzed. PGA homopolymers exhibited an approximately 30 °C difference between Tm and Tc, which increased to 68 °C by incorporating up to 10% methyl groups in the chain while maintaining overall thermal stability. Oxygen and water vapor permeation values of solvent-cast nonoriented films of PGA homopolymers were found to be 4.6 cc·mil·m-2·d-1·atm-1 and 2.6 g·mil·m-2·d-1·atm-1, respectively. Different methyl distributions in the copolymer sequence, provided through either lactide or methyl glycolide, affected the resulting gas barrier properties. At 10% methyl insertion, using lactide as a comonomer significantly increased both O2 (32 cc·mil·m-2·d-1·atm-1) and water vapor (12 g·mil·m-2·d-1·atm-1) permeation. However, when methyl glycolide was utilized for methyl insertion at 10% Me content, excellent barrier properties for both O2 (2.9 cc·mil·m-2·d-1·atm-1) and water vapor (1.0 g·mil·m-2·d-1·atm-1) were achieved.

Sterically-Locked Donor-Acceptor Conjugated Polymers Showing Efficient Thermally Activated Delayed Fluorescence.

Donor-acceptor (D-A) conjugated polymers often possess a significant frontier molecular orbital overlap because of the conjugation elongation, leading to no thermally activated delayed fluorescence (TADF) caused by a large singlet-triplet energy splitting (▵EST ). Herein a novel steric locking strategy is proposed by incorporating methyl groups into D-A conjugated polymers. Benefitting from the methyl hindrance, the torsion between the donor and acceptor can be well tuned to form a sterically-locked conformation, so that the unwanted relaxation toward planarity and thus conjugation elongation is prevented to boost hole-electron separation. The resultant D-A conjugated polymer achieves an extremely low ΔEST of 0.09 eV to enable efficient TADF. The corresponding doped and non-doped devices are fabricated via a solution process, revealing a record-high external quantum efficiency (EQE) of 24.0 % (79.4 cd A-1 , 75.0 lm W-1 ) and 15.3 % (50.9 cd A-1 , 47.3 lm W-1 ).

Sterically‐Locked Donor–Acceptor Conjugated Polymers Showing Efficient Thermally Activated Delayed Fluorescence

AbstractDonor–acceptor (D–A) conjugated polymers often possess a significant frontier molecular orbital overlap because of the conjugation elongation, leading to no thermally activated delayed fluorescence (TADF) caused by a large singlet‐triplet energy splitting (▵EST). Herein a novel steric locking strategy is proposed by incorporating methyl groups into D–A conjugated polymers. Benefitting from the methyl hindrance, the torsion between the donor and acceptor can be well tuned to form a sterically‐locked conformation, so that the unwanted relaxation toward planarity and thus conjugation elongation is prevented to boost hole–electron separation. The resultant D–A conjugated polymer achieves an extremely low ΔEST of 0.09 eV to enable efficient TADF. The corresponding doped and non‐doped devices are fabricated via a solution process, revealing a record‐high external quantum efficiency (EQE) of 24.0 % (79.4 cd A−1, 75.0 lm W−1) and 15.3 % (50.9 cd A−1, 47.3 lm W−1).

Cytosine methylation of mature microRNAs inhibits their functions and is associated with poor prognosis in glioblastoma multiforme

BackgroundLiterature reports that mature microRNA (miRNA) can be methylated at adenosine, guanosine and cytosine. However, the molecular mechanisms involved in cytosine methylation of miRNAs have not yet been fully elucidated. Here we investigated the biological role and underlying mechanism of cytosine methylation in miRNAs in glioblastoma multiforme (GBM).MethodsRNA immunoprecipitation with the anti-5methylcytosine (5mC) antibody followed by Array, ELISA, dot blot, incorporation of a radio-labelled methyl group in miRNA, and miRNA bisulfite sequencing were perfomred to detect the cytosine methylation in mature miRNA. Cross-Linking immunoprecipiation qPCR, transfection with methylation/unmethylated mimic miRNA, luciferase promoter reporter plasmid, Biotin-tagged 3’UTR/mRNA or miRNA experiments and in vivo assays were used to investigate the role of methylated miRNAs. Finally, the prognostic value of methylated miRNAs was analyzed in a cohorte of GBM pateints.ResultsOur study reveals that a significant fraction of miRNAs contains 5mC. Cellular experiments show that DNMT3A/AGO4 methylated miRNAs at cytosine residues inhibit the formation of miRNA/mRNA duplex and leading to the loss of their repressive function towards gene expression. In vivo experiments show that cytosine-methylation of miRNA abolishes the tumor suppressor function of miRNA-181a-5p miRNA for example. Our study also reveals that cytosine-methylation of miRNA-181a-5p results is associated a poor prognosis in GBM patients.ConclusionTogether, our results indicate that the DNMT3A/AGO4-mediated cytosine methylation of miRNA negatively.Graphical abstract

Histone H2A isoforms: Potential implications in epigenome plasticity and diseases in eukaryotes

Epigenetic mechanisms including the post-translational modifications of histones, incorporation of histone variants and DNA methylation have been suggested to play an important role in genome plasticity by allowing the cellular environment to define gene expression and the phenotype of an organism. Studies over the past decade have elucidated how these epigenetic mechanisms are significant in orchestrating various biological processes and contribute to different pathophysiological states. However, the role of histone isoforms and their impact on different phenotypes and physiological processes associated with diseases are not fully clear. This review is focussed on the recent advances in our understanding of the complexity of eukaryotic H2A isoforms and their roles in defining nucleosome organization. We elaborate on their potential roles in genomic complexity and regulation of gene expression, and thereby on their overall contribution towards cellular phenotype and development of diseases.

1,4-D-Glucan block copolymers: synthesis and comprehensive structural characterization

Multi-block glucans comprising permethylated and partially methylated blocks are compounds of interest. In order to monitor their formation by transglycosylation of corresponding starting glucans, a method has been developed and applied to model compounds. This method allows determining the average length of the blocks and the progress of incorporation of methyl blocks in partially methylated sequences with a random distribution. The method, comprising liquid chromatography mass spectrometry (LC-MS) and electrospray ionization collision-induced dissociation tandem mass spectrometry (ESI-CID-MSn) measurements of two types of peralkylated glucans representing derivatives of the target compounds, is comprehensively described and discussed. ESI-MSn allows looking into the sequences of oligomeric domains. In addition, transglycosylation is followed by attenuated total reflection FTIR and NMR spectroscopy.Graphical abstract

A novel stable isotope tracer method to simultaneously quantify skeletal muscle protein synthesis and breakdown

Background/aimsMethodological challenges have been associated with the dynamic measurement of muscle protein breakdown (MPB), as have the measurement of both muscle protein synthesis (MPS) and MPB within the same experiment. Our aim was to use the transmethylation properties of methionine as proof-of-concept to measure rates of MPB via its methylation of histidine within skeletal muscle myofibrillar proteins, whilst simultaneously utilising methionine incorporation into bound protein to measure MPS. ResultsDuring the synthesis measurement period, incorporation of methyl[D3]-13C-methionine into cellular protein in C2C12 myotubes was observed (representative of MPS), alongside an increase in the appearance of methyl[D3]-methylhistidine into the media following methylation of histidine (representative of MPB). For further validation of this approach, fractional synthetic rates (FSR) of muscle protein were increased following treatment of the cells with the anabolic factors insulin-like growth factor-1 (IGF-1) and insulin, while dexamethasone expectedly reduced MPS. Conversely, rates of MPB were reduced with IGF-1 and insulin treatments, whereas dexamethasone accelerated MPB. ConclusionsThis is a novel stable isotope tracer approach that permits the dual assessment of muscle cellular protein synthesis and breakdown rates, through the provision of a single methionine amino acid tracer that could be utilised in a wide range of biological settings.