| Size | Price | Stock | Qty |
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| 1mg |
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| Other Sizes |
| Targets |
L-Isoleucine-13C6 targets the same pathways as unlabeled L-Isoleucine. As a branched-chain amino acid (BCAA), L-Isoleucine is a substrate for the enzyme branched-chain aminotransferase (BCAT), which converts it to its corresponding alpha-keto acid (alpha-keto-beta-methylvaleric acid). This alpha-keto acid is then decarboxylated by the branched-chain alpha-keto acid dehydrogenase complex (BCKDH). BCAA metabolism plays a key role in energy homeostasis, muscle protein synthesis, and the regulation of insulin signaling. L-Isoleucine also activates the mTOR signaling pathway, promoting protein synthesis. As a tracer, the 13C label allows researchers to track the fate of isoleucine carbons in metabolic pathways.
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| ln Vitro |
Drug compounds have included stable heavy isotopes of carbon, hydrogen, and other elements, mostly as quantitative tracers while the drugs were being developed. Because deuteration may have an effect on a drug's pharmacokinetics and metabolic properties, it is a cause for concern [1].
As a stable isotope tracer, L-Isoleucine-13C6 is not used to measure biological activity in the traditional sense. Instead, it is added to cell culture media or administered to animals to track BCAA metabolism, protein synthesis, and carbon flux. In vitro, L-Isoleucine (unlabeled) at concentrations of 0.1-5 mM is used to study BCAA metabolism in hepatocytes, myotubes, and adipocytes. It promotes muscle protein synthesis via mTOR activation and is used in cell culture media formulations. The 13C-labeled version is used to quantify BCAA catabolism: the conversion of isoleucine-13C6 to its alpha-keto acid and to TCA cycle intermediates (e.g., succinyl-CoA) is measured by LC-MS. L-Isoleucine is an essential amino acid that cannot be synthesized by humans and must be obtained from the diet. |
| ln Vivo |
In vivo, L-Isoleucine-13C6 is administered to animals to trace BCAA metabolism, protein synthesis rates, and metabolic flux through the BCAA catabolic pathway. The compound is used to study the role of BCAAs in metabolic diseases such as type 2 diabetes, obesity, and insulin resistance, where elevated plasma BCAAs are a hallmark. In animals, L-Isoleucine (unlabeled) is required for growth, muscle maintenance, and immune function. The 13C-labeled version is used to quantify the conversion of isoleucine to succinyl-CoA via the BCAA catabolic pathway and its entry into the TCA cycle. It is also used to measure protein synthesis rates using the flooding dose method or steady-state isotope labeling. In nutritional studies, L-Isoleucine-13C6 is used to determine amino acid requirements and the bioavailability of isoleucine from dietary proteins.
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| Enzyme Assay |
For non-cellular assays (analytical quantification), L-Isoleucine-13C6 is prepared as a stock solution in water or 0.1 M HCl (1 mg/mL). For LC-MS/MS analysis, a calibration curve for L-Isoleucine is prepared in human plasma (0.1-1000 ng/mL) with a fixed concentration of L-Isoleucine-13C6 (e.g., 50 ng/mL). Sample preparation: 100 uL plasma + 20 uL internal standard + 380 uL acetonitrile for protein precipitation. After centrifugation, the supernatant is diluted with water (1:1) and injected onto a C18 column or a HILIC column with a mobile phase of 0.1% formic acid in water and acetonitrile (gradient elution). MRM transitions: L-Isoleucine 132→86 (loss of H2O), L-Isoleucine-13C6 138→92. For BCAT activity assays, purified BCAT is incubated with L-Isoleucine-13C6 (1-10 mM) in assay buffer, and the labeled alpha-keto acid product is quantified by LC-MS. For BCKDH activity assays, the BCKDH complex is incubated with alpha-keto acid-13C6 derived from isoleucine, and decarboxylation is measured by 13CO2 production or by LC-MS.
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| Cell Assay |
For cell-based assays, hepatocytes (e.g., HepG2 cells), myotubes (differentiated C2C12 cells), or adipocytes (3T3-L1) are seeded in 6-well plates (1×10⁶ cells/well) in DMEM with 10% FBS. For metabolic labeling, cells are cultured in medium lacking unlabeled isoleucine and supplemented with L-Isoleucine-13C6 (10-100 uM) for 6-48 hours. Cell lysates are prepared in 80% methanol containing internal standards. 13C enrichment in isoleucine, its alpha-keto acid, TCA cycle intermediates (succinate, fumarate), and proteins is analyzed by LC-MS/MS or GC-MS. For protein synthesis studies, cells are incubated with L-Isoleucine-13C6 for 1-24 hours, and the rate of incorporation into newly synthesized proteins is measured by MS analysis of hydrolyzed proteins. For mTOR signaling studies, cells are starved of BCAAs and then stimulated with L-Isoleucine, and phosphorylation of S6K1 and 4E-BP1 is measured by Western blot.
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| Animal Protocol |
For in vivo animal experiments, rats or mice are fasted overnight and then administered L-Isoleucine-13C6 orally (gavage) at a dose of 20-100 mg/kg or intravenously at 5-50 mg/kg. Blood samples are collected at multiple time points (0, 15, 30, 60, 90, 120 minutes) from the tail vein. Plasma is separated, and proteins are precipitated with methanol. At the end of the experiment, tissues (liver, skeletal muscle, adipose tissue, heart) are harvested and homogenized. L-Isoleucine-13C6 and its metabolites (alpha-keto acid, TCA cycle intermediates) are analyzed by LC-MS/MS. For protein synthesis studies (flooding dose method), a large dose of L-Isoleucine-13C6 (150-300 mg/kg) is administered to achieve uniform labeling of the free amino acid pool, and the rate of incorporation into muscle proteins is measured over 30-60 minutes. For nutritional studies, animals are fed a diet containing L-Isoleucine-13C6 for 7-14 days, and protein-bound isoleucine enrichment is measured in tissues to determine protein turnover rates.
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| ADME/Pharmacokinetics |
L-Isoleucine-13C6 has a molecular weight of 137.13, with six carbon-13 atoms (mass shift +6) relative to unlabeled L-Isoleucine (MW 131.17). The compound is a white crystalline powder with a melting point of 284degC (dec.). It is soluble in water (approximately 20 mg/mL) and dilute acids and bases. The 13C label is stable and non-radioactive. It should be stored as a powder at -20degC for up to 3 years, and in solution at -80degC for up to 6 months or at -20degC for up to 1 month. The compound is metabolically identical to unlabeled L-Isoleucine, so its pharmacokinetics follow that of L-Isoleucine: absorbed via amino acid transporters (e.g., LAT1, LAT2, B⁰AT1) in the small intestine, distributed to all tissues, and incorporated into proteins or catabolized via the BCAA catabolic pathway primarily in skeletal muscle and liver.
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| Toxicity/Toxicokinetics |
L-Isoleucine-13C6 is a stable isotope-labeled compound with minimal toxicity at analytical and tracer concentrations (mg per kg body weight in animals). The non-deuterated parent compound, L-Isoleucine, is an essential amino acid that is generally recognized as safe (GRAS) as a dietary supplement and food additive. At typical dietary intake levels (50-100 mg/kg/day), it is well-tolerated. High doses (≥500 mg/kg) may cause mild gastrointestinal discomfort, and in individuals with maple syrup urine disease (MSUD, a genetic disorder of BCAA metabolism), isoleucine accumulation can cause neurological toxicity. However, at tracer doses, these effects are not observed. The compound is non-radioactive and safe for research use with standard handling precautions for amino acids.
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| References | |
| Additional Infomation |
L-Isoleucine-13C6 is a research compound used as a stable isotope tracer, not an approved drug. It is not intended for therapeutic use and has not undergone clinical trials as a drug. Its primary applications are in metabolic research, including studying branched-chain amino acid (BCAA) metabolism, protein synthesis rates, metabolic flux through the BCAA catabolic pathway, and the role of BCAAs in metabolic diseases (e.g., type 2 diabetes, obesity, insulin resistance, heart failure). The compound is used in nutritional studies to determine amino acid requirements, bioavailability of dietary proteins, and protein turnover rates (in combination with the flooding dose technique). L-Isoleucine-13C6 is also used as an internal standard for quantitative LC-MS analysis of L-Isoleucine in biological and clinical samples. Available for research use only.
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| Molecular Formula |
C6H13NO2
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| Molecular Weight |
137.128850698471
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| Exact Mass |
137.114
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| CAS # |
201740-82-1
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| Related CAS # |
L-Isoleucine;73-32-5
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| PubChem CID |
101365134
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| Appearance |
White to off-white solid powder
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| LogP |
-1.7
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| Hydrogen Bond Donor Count |
2
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| Hydrogen Bond Acceptor Count |
3
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| Rotatable Bond Count |
3
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| Heavy Atom Count |
9
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| Complexity |
103
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| Defined Atom Stereocenter Count |
2
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| SMILES |
[13CH3][13CH2][13C@H]([13CH3])[13C@@H]([13C](=O)O)N
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| InChi Key |
AGPKZVBTJJNPAG-CPLGCGHPSA-N
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| InChi Code |
InChI=1S/C6H13NO2/c1-3-4(2)5(7)6(8)9/h4-5H,3,7H2,1-2H3,(H,8,9)/t4-,5-/m0/s1/i1+1,2+1,3+1,4+1,5+1,6+1
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| Chemical Name |
(2S,3S)-2-amino-3-(113C)methyl(1,2,3,4,5-13C5)pentanoic acid
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| HS Tariff Code |
2934.99.9001
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| Storage |
Powder -20°C 3 years 4°C 2 years In solvent -80°C 6 months -20°C 1 month |
| Shipping Condition |
Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)
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| Solubility (In Vitro) |
May dissolve in DMSO (in most cases), if not, try other solvents such as H2O, Ethanol, or DMF with a minute amount of products to avoid loss of samples
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| Solubility (In Vivo) |
Note: Listed below are some common formulations that may be used to formulate products with low water solubility (e.g. < 1 mg/mL), you may test these formulations using a minute amount of products to avoid loss of samples.
Injection Formulations
Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline)(e.g. IP/IV/IM/SC) *Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH ₂ O to obtain a clear solution. Injection Formulation 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL DMSO → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline) Injection Formulation 3: DMSO : Corn oil = 10 : 90 (i.e. 100 μL DMSO → 900 μL Corn oil) Example: Take the Injection Formulation 3 (DMSO : Corn oil = 10 : 90) as an example, if 1 mL of 2.5 mg/mL working solution is to be prepared, you can take 100 μL 25 mg/mL DMSO stock solution and add to 900 μL corn oil, mix well to obtain a clear or suspension solution (2.5 mg/mL, ready for use in animals). View More
Injection Formulation 4: DMSO : 20% SBE-β-CD in saline = 10 : 90 [i.e. 100 μL DMSO → 900 μL (20% SBE-β-CD in saline)] Oral Formulations
Oral Formulation 1: Suspend in 0.5% CMC Na (carboxymethylcellulose sodium) Oral Formulation 2: Suspend in 0.5% Carboxymethyl cellulose Example: Take the Oral Formulation 1 (Suspend in 0.5% CMC Na) as an example, if 100 mL of 2.5 mg/mL working solution is to be prepared, you can first prepare 0.5% CMC Na solution by measuring 0.5 g CMC Na and dissolve it in 100 mL ddH2O to obtain a clear solution; then add 250 mg of the product to 100 mL 0.5% CMC Na solution, to make the suspension solution (2.5 mg/mL, ready for use in animals). View More
Oral Formulation 3: Dissolved in PEG400 (Please use freshly prepared in vivo formulations for optimal results.) |
| Preparing Stock Solutions | 1 mg | 5 mg | 10 mg | |
| 1 mM | 7.2924 mL | 36.4618 mL | 72.9235 mL | |
| 5 mM | 1.4585 mL | 7.2924 mL | 14.5847 mL | |
| 10 mM | 0.7292 mL | 3.6462 mL | 7.2924 mL |
*Note: Please select an appropriate solvent for the preparation of stock solution based on your experiment needs. For most products, DMSO can be used for preparing stock solutions (e.g. 5 mM, 10 mM, or 20 mM concentration); some products with high aqueous solubility may be dissolved in water directly. Solubility information is available at the above Solubility Data section. Once the stock solution is prepared, aliquot it to routine usage volumes and store at -20°C or -80°C. Avoid repeated freeze and thaw cycles.
Calculation results
Working concentration： mg/mL；
Method for preparing DMSO stock solution： mg drug pre-dissolved in μL DMSO (stock solution concentration mg/mL). Please contact us first if the concentration exceeds the DMSO solubility of the batch of drug.
Method for preparing in vivo formulation:：Take μL DMSO stock solution, next add μL PEG300, mix and clarify, next addμL Tween 80, mix and clarify, next add μL ddH2O，mix and clarify.
(1) Please be sure that the solution is clear before the addition of next solvent. Dissolution methods like vortex, ultrasound or warming and heat may be used to aid dissolving.
(2) Be sure to add the solvent(s) in order.
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