| Size | Price | Stock | Qty |
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| 10mg |
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| 25mg |
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| 50mg |
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| 100mg |
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| 250mg |
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| Targets |
The molecular target of Mc-Phe-Lys(Boc)-PAB is not a biological target per se, but rather it is a chemical linker used in the synthesis of ADCs. In the context of an ADC, the linker connects the antibody (which targets a cell surface antigen) to the cytotoxic drug payload. The maleimide group reacts with reduced cysteine residues on the antibody to form a stable thioether bond. The Phe-Lys dipeptide is designed to be cleaved by cathepsin B, a lysosomal protease that is overexpressed in many cancer cells. The Boc-protected ε-amine on the lysine residue provides stability during synthesis and can be deprotected when needed. The PAB group undergoes self-immolation upon cleavage of the dipeptide, releasing the drug payload. The ultimate biological target of the complete ADC would be the specific antigen recognized by the antibody, which could be HER2, CD30, CD33, or other tumor-associated antigens.
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| ln Vitro |
In vitro activity of Mc-Phe-Lys(Boc)-PAB is not assessed as a standalone compound, as it is a linker molecule rather than a therapeutic agent. Its activity is evaluated in the context of the complete ADC, where the linker's role is to deliver the cytotoxic payload to target cells. In cell-based assays, ADCs constructed with Mc-Phe-Lys(Boc)-PAB would be tested for antigen-specific cytotoxicity against cancer cell lines expressing the target antigen. The linker's efficiency is assessed by measuring the potency of the ADC (IC50) compared to the free drug, as well as the selectivity for antigen-positive versus antigen-negative cells. The stability of the linker in serum is also evaluated to ensure that the drug is not released prematurely. The self-immolative PAB group ensures that the drug is efficiently released inside the target cell upon lysosomal processing. Specific IC50 values would depend on the antibody, the drug payload, and the target antigen.
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| ln Vivo |
In vivo activity of Mc-Phe-Lys(Boc)-PAB is evaluated in the context of complete ADCs in animal models. ADCs incorporating this linker would be tested in xenograft models where human tumor cells expressing the target antigen are implanted in immunodeficient mice. The ADC would be administered intravenously at doses typically ranging from 1 to 30 mg/kg, often on a weekly or biweekly schedule for 2-4 weeks. Tumor growth inhibition would be measured, along with survival extension. The linker's in vivo stability, pharmacokinetics, and biodistribution would also be assessed. ADCs with this type of cleavable linker are designed to release the drug payload specifically within tumor cells, thereby maximizing efficacy and minimizing systemic toxicity. The in vivo efficacy of the ADC would depend on the antibody targeting, the potency of the drug payload, and the linker's cleavage efficiency in the tumor microenvironment.
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| Enzyme Assay |
For in vitro linker conjugation and stability assays, the following protocol is used: the antibody (e.g., trastuzumab) is reduced with TCEP (tris(2-carboxyethyl)phosphine) at 37°C for 2 hours to generate free thiol groups on cysteine residues. The number of free thiols is determined using Ellman's reagent. Mc-Phe-Lys(Boc)-PAB is dissolved in DMSO and added to the reduced antibody in a buffer containing 20 mM histidine (pH 5.5) and 2 mM EDTA, at a molar ratio of 5-10:1 (linker:antibody). The conjugation reaction is carried out at room temperature for 1-2 hours. The excess linker is removed by dialysis or size-exclusion chromatography. The resulting ADC is characterized by HIC-HPLC, SEC-HPLC, and LC-MS to determine the drug-to-antibody ratio (DAR). For stability studies, the ADC is incubated in human plasma or serum at 37°C for up to 7 days, and samples are analyzed by SEC-HPLC to monitor aggregation and by LC-MS to assess drug release. For cathepsin B cleavage assays, the linker is incubated with recombinant cathepsin B at 37°C for 2-24 hours in acetate buffer (pH 5.5) containing DTT, and the released drug is quantified by HPLC.
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| Cell Assay |
For in vitro cell-based assays with ADCs containing Mc-Phe-Lys(Boc)-PAB, the following typical protocol is used: target antigen-positive cancer cells (e.g., HER2-positive SK-BR-3 or BT-474 cells) and antigen-negative cells (e.g., MDA-MB-468) are cultured in appropriate media at 37°C in 5% CO₂. Cells are seeded in 96-well plates at 5,000-10,000 cells per well and allowed to adhere overnight. The ADC is serially diluted in culture medium to final concentrations ranging from 0.001 to 100 μg/mL (based on antibody concentration). Cells are treated with the ADC for 72-120 hours. Cell viability is assessed using the CellTiter-Glo or MTT assay. IC50 values are calculated from dose-response curves. For mechanistic studies, cells are treated with the ADC for 24-48 hours, and apoptosis is assessed by flow cytometry using Annexin V/PI staining. Cell cycle analysis is performed by propidium iodide staining. The specificity of the ADC is confirmed by the lack of activity against antigen-negative cells and by competition with excess unconjugated antibody.
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| Animal Protocol |
For in vivo animal studies with ADCs incorporating Mc-Phe-Lys(Boc)-PAB, the following general protocol is used: female athymic nude mice (6-8 weeks old, 18-22 g) are subcutaneously injected with 5-10 × 10⁶ target antigen-positive tumor cells (e.g., BT-474 or NCI-N87 for HER2) in the flank. When tumors reach approximately 100-200 mm³, mice are randomized into treatment groups (n=8-10 per group). The ADC is administered intravenously via the tail vein at doses of 1, 3, 10, and 30 mg/kg on days 1, 8, 15, and 22 (weekly for 3-4 weeks). Tumor volumes are measured twice weekly with calipers and calculated as (length × width²)/2. Body weights are monitored for toxicity assessment. At the end of the study, tumors are excised, weighed, and processed for histopathology and immunohistochemistry. Blood samples are collected for pharmacokinetic analysis to measure ADC concentration, total antibody, and released drug.
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| ADME/Pharmacokinetics |
Mc-Phe-Lys(Boc)-PAB (CAS# 756487-18-0) is an ADC linker featuring a maleimide, a Phe-Lys dipeptide with a Boc-protected ε-amine, and a PAB group. It has a molecular formula of C37H49N5O8 and a molecular weight of 691.81 g/mol. The maleimide group is for conjugation to antibodies, the Phe-Lys dipeptide is cleaved by cathepsin B in the lysosome, and the PAB group provides self-immolative drug release. Future research could focus on optimizing the linker for specific ADC applications, evaluating its stability and cleavage efficiency in different tumor types, and developing new drug payloads and antibody combinations to improve the therapeutic index of ADCs.
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| Molecular Formula |
C37H49N5O8
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| Molecular Weight |
691.813669919968
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| Exact Mass |
691.36
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| Elemental Analysis |
C, 64.24; H, 7.14; N, 10.12; O, 18.50
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| CAS # |
756487-18-0
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| PubChem CID |
155908175
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| Appearance |
Solid powder
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| LogP |
3
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| Hydrogen Bond Donor Count |
5
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| Hydrogen Bond Acceptor Count |
8
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| Rotatable Bond Count |
21
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| Heavy Atom Count |
50
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| Complexity |
1150
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| Defined Atom Stereocenter Count |
2
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| SMILES |
CC(C)(C)OC(=O)NCCCC[C@@H](C(=O)NC1=CC=C(C=C1)CO)NC(=O)[C@H](CC2=CC=CC=C2)NC(=O)CCCCCN3C(=O)C=CC3=O
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| InChi Key |
TUPIPBYBJMCLLM-KYJUHHDHSA-N
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| InChi Code |
InChI=1S/C37H49N5O8/c1-37(2,3)50-36(49)38-22-10-9-14-29(34(47)39-28-18-16-27(25-43)17-19-28)41-35(48)30(24-26-12-6-4-7-13-26)40-31(44)15-8-5-11-23-42-32(45)20-21-33(42)46/h4,6-7,12-13,16-21,29-30,43H,5,8-11,14-15,22-25H2,1-3H3,(H,38,49)(H,39,47)(H,40,44)(H,41,48)/t29-,30-/m0/s1
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| Chemical Name |
tert-butyl N-[(5S)-5-[[(2S)-2-[6-(2,5-dioxopyrrol-1-yl)hexanoylamino]-3-phenylpropanoyl]amino]-6-[4-(hydroxymethyl)anilino]-6-oxohexyl]carbamate
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| Synonyms |
TKN87180; TKN-87180; TKN 87180;
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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 | 1.4455 mL | 7.2274 mL | 14.4548 mL | |
| 5 mM | 0.2891 mL | 1.4455 mL | 2.8910 mL | |
| 10 mM | 0.1445 mL | 0.7227 mL | 1.4455 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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