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APYTFGQGTK – SIL Adalimumab signature peptide

APYTFGQGTK peptide is a sequence from light chain of Adalimumab monoclonal antibody. Due to its universal location in Adalimumab antibody, Stable Isotope Labeled (SIL) APYTFGQGTK is used as a specific signature peptide for  the quantitation of Adalimumab.

Indeed, proteomic studies allows quantification of proteins in blood samples. By this way, APYTFGQGTK peptide can be isotope labeled and used as an internal standard for Liquid Chromatography/ Mass Spectrometry (LC/MS) analysis. 

Using 13C and 15N-labeled Lysine, the heavy Adalimumab peptide sequence will have an increased mass but will keep the same properties. With a high sensitive and specific level, bioanalytical studies with stable isotope labeled signature peptides corresponds to the gold standard for accurate targeted quantitative proteomics.

What is Adalimumab?

Adalimumab corresponds to a therapeutic monoclonal antibody. It is a subcutaneously administered biological disease modifier for the treatment of rheumatoid arthritis and other chronic debilitating diseases mediated by tumor necrosis factor. This drug is frequently known as Humira.

1 Rheumatoid Arthritis Moderate to severe
2 Juvenile Idiopathic arthritis Moderately to severely active
3 Psoriatic arthritis Active
4 Ankylosing spondylitis Active
5 Crohn's disease Moderately to severely active
6 Ulcerative colitis Moderately to severely active
7 Plaque psoriasis Moderate to severe chronic
8 Hidradenitis suppurativa Moderate to severe
9 Pyoderma gangrenosum Off-label

Technical specification

heavy SIL adalimumab buy Sequence : APYTFGQGT-K*-  [K*= K(13C,15N)]
heavy SIL adalimumab synthesis MW : 1 077.17 Da
adalimumab peptide standard price Purity : > 95%
adalimumab peptide standard synthesis Counter-Ion : TFA Salts (see option TFA removal)
Peptide library synthesis abeta peptide Delivery format : Freeze dried in propylene 2mL microtubes
buy synthesized peptide standard Other name : Adalimumab signature peptide
adalimumab internal standard solubility guidelines Peptide Solubility Guideline
buy peptide price Bulk peptide quantities available



Catalog code Size Price € Price $ USD
SB042-0.1MG 0.1 mg 190 237
SB042-1MG 1 mg 830 1037



1- Jourdil, Jean-François MS et al. Therapeutic Drug Monitoring. (2018)
Simultaneous Quantification of Adalimumab and Infliximab in Human Plasma by Liquid Chromatography–Tandem Mass Spectrometry


Background: Adalimumab (ADA) and infliximab (IFX) are therapeutic monoclonal antibodies targeting tumor necrosis factor-alpha (TNFα). They are used to treat inflammatory diseases. Clinical trials have suggested that therapeutic drug monitoring for ADA or IFX could improve treatment response and cost effectiveness. However, ADA and IFX were quantified by ELISA in all these studies, and the discrepancies between the results obtained raise questions about their reliability. We describe here the validation of a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the simultaneous quantification of ADA and IFX in human samples.

Methods: Full-length antibodies labeled with stable isotopes were added to plasma samples as an internal standard. Samples were then prepared using Mass Spectrometry Immunoassay followed by trypsin digestion before ADA and IFX quantification by LC-MS/MS. ADA and IFX were quantified in serum from patients treated with ADA (n = 21) or IFX (n = 22), and the concentrations obtained were compared with those obtained with a commercial ELISA kit.

Results: The chromatography run lasted 8.6 minutes, and the quantification range was 1-26 mg/L. The method was reproducible, repeatable, and accurate. For both levels of internal quality control, for ADA and IFX, interday and intraday coefficients of variation and accuracies were all within 15%, in accordance with FDA recommendations. No significant cross-contamination effect was noted. Good agreement was found between LC-MS/MS and ELISA results, for both ADA and IFX.

Conclusions: This LC-MS/MS method can be used for the quantification of ADA and IFX in a single analytical run and for the optimization of LC-MS/MS resource use in clinical pharmacology laboratories.

2- Park, Y et al. Pharmaceutics. (2018)
Qualification and Application of a Liquid Chromatography-Quadrupole Time-of-Flight Mass Spectrometric Method for the Determination of Adalimumab in Rat Plasma



A liquid chromatography–quadrupole time-of-flight (Q-TOF) mass spectrometric method was developed for early-stage research on adalimumab in rats. The method consisted of immunoprecipitation followed by tryptic digestion for sample preparation and LC-QTOF-MS/MS analysis of specific signature peptides of adalimumab in the positive ion mode using electrospray ionization. This specific signature peptide is derived from the complementarity-determining region (CDR) of adalimumab. A quadratic regression (weighted 1/concentration), with an equation y = ax2 + bx + c, was used to fit calibration curves over the concentration range of 1–100 μg/mL for adalimumab. The qualification run met the acceptance criteria of ±25% accuracy and precision values for quality control (QC) samples. This qualified LC-QTOF-MS/MS method was successfully applied to a pharmacokinetic study of adalimumab in rats as a case study. This LC-QTOF-MS/MS approach would be useful as a complementary method for adalimumab or its biosimilars at an early stage of research.

3- Théo Willeman et al. Analytica Chimica Acta (2019)
A multiplex liquid chromatography tandem mass spectrometry method for the quantification of seven therapeutic monoclonal antibodies: Application for adalimumab therapeutic drug monitoring in patients with Crohn’s disease



The use of therapeutic monoclonal antibodies (mAbs) is steadily increasing. Previous studies have reported the clinical interest of mAb therapeutic-drug monitoring (TDM), including that of adalimumab, for patients with Crohn’s disease (CD). Proof of concept mAb-quantification studies by liquid chromatography mass spectrometry (LC-MS/MS) have been published, but a specific and reliable routine-suited multiplex quantification method is still needed to facilitate mAb TDM.

We describe an electrospray ionization LC-MS/MS method for the simultaneous quantification of seven mAbs (adalimumab, cetuximab, infliximab, rituximab, secukinumab, tocilizumab, and trastuzumab) in human plasma. Sample preparation was performed using protein-G purification and trypsin digestion to obtain proteotypic peptides. We retrospectively measured the adalimumab concentration in 65 plasma samples from 56 CD patients and determined the adalimumab therapeutic cut-off concentration associated with biological remission.

Calibration curves were linear from 1 to 100 μg mL−1, except for rituximab (5–100 μg mL−1). This method was reproducible, repeatable, and accurate (coefficient of variation and bias < 20%), with no cross contamination. Adalimumab concentrations were significantly higher (p = 0.0198) for patients with biological remission (median: 11.3 μg mL−1 [4.6; 18.3]) than that for patients without a biological response (9.5 μg mL−1 [3.94;17.0]). An adalimumab cut-off concentration of 8.0 μg mL−1 correctly discriminated patients with or without biological remission (sensitivity: 74.1%, specificity: 57.9%).

This validated LC-MS/MS routine-suited method is the first allowing simultaneous quantification of up to seven mAbs acting against different pharmacological targets. It opens the field of TDM to numerous mAbs.