Blocking Peptides
Blocking peptides are synthesised as epitope-matched replicas of the sequence recognised by their corresponding antibody. Pre-incubating an antibody with its matching peptide competitively blocks that binding site, so a loss of signal in Western blot, IHC, or ELISA confirms the antibody was detecting that target specifically rather than an off-target site.
Browse Blocking PeptidesConfirming Antibody Specificity Through Peptide Competition
Peptide competition works by occupying an antibody's binding site before the antibody reaches the assay sample. A blocking peptide is synthesised to match the exact epitope recognised by its corresponding antibody, so pre-incubating the antibody with an excess of peptide saturates that binding site. When the pre-incubated antibody is then applied to a Western blot, IHC section, or ELISA well, a genuine reduction or loss of signal compared with the same antibody run without peptide indicates the antibody was binding that specific epitope rather than an off-target site.
General Workflow: Confirming Specificity With a Blocking Peptide
Pre-incubation → parallel assay → signal comparison
Pre-incubate the antibody
Combine the primary antibody with a molar excess of its matching blocking peptide and incubate under the conditions used for the intended assay.
Run in parallel
Apply the peptide-blocked antibody to a Western blot, IHC section, or ELISA well alongside the same antibody without peptide, under identical conditions.
Compare signal
Loss of signal in the peptide-blocked sample relative to the unblocked control confirms the antibody was detecting that specific epitope.
Two Targets Worth a Closer Look
These two blocking peptides anchor two of the most frequently referenced target classes in the range: a synucleinopathy research target central to Parkinson's disease studies, and a tyrosine kinase target central to leukaemia research.
Alpha Synuclein Blocking Peptide (STJ504398)
Alpha synuclein aggregation into Lewy bodies is a defining neuropathological hallmark of Parkinson's disease and related synucleinopathies.1 Because antibody specificity is central to interpreting synuclein pathology in tissue and cell models, pre-incubating an alpha synuclein antibody with this matching peptide is a standard step for confirming the antibody is binding its intended epitope before use in IHC or Western blot.
View product →ABL1 Blocking Peptide (STJ505401)
ABL1 is a non-receptor tyrosine kinase whose constitutively active BCR-ABL1 fusion form drives chronic myeloid leukaemia, making it one of the most extensively studied kinase targets in cancer research.2 Because tyrosine kinases share conserved catalytic domains within their family, peptide competition confirms an ABL1 antibody is binding the intended kinase rather than a structurally related family member.
View product →Blocking Peptides for Serotonin Receptor and GPCR Targets
Blocking peptides for the 5HT1A, 5HT1B, 5HT2A and 5HT2C serotonin receptor subtypes. These G protein-coupled receptors share close amino acid sequence homology within the same subfamily, which makes peptide competition a standard step for confirming that a 5HT receptor antibody is binding its intended subtype rather than a related receptor, before that antibody is used in IHC or Western blot work on serotonergic signalling.
Blocking Peptides for Kinase and Signal Transduction Targets
Blocking peptides for ABL1, ABL2, ACK1, AKT1, AMPK alpha 1 and AMPK alpha 2. ABL1 and ABL2 are non-receptor tyrosine kinases studied in leukaemia research,2 ACK1 is a tyrosine kinase activated downstream of receptor signalling, and AKT1 together with the two AMPK alpha subunits sit within kinase pathways that regulate cell growth and cellular energy status. Kinase family members frequently share conserved catalytic domains, so peptide competition is used to confirm an antibody is binding the intended kinase rather than a close relative before it is used to draw conclusions from an experiment.
Blocking Peptides for Oncology and Metabolic Biomarker Targets
Blocking peptides for AMACR, Alpha Fetoprotein, Adiponectin and AIM2. AMACR is used as a sensitive and specific marker for distinguishing malignant from benign glands in prostate biopsies,3 and Alpha Fetoprotein is a long-established serum and tissue marker in hepatocellular carcinoma diagnostics. Adiponectin is studied as an adipokine secreted by adipose tissue with roles in glucose and lipid metabolism, and AIM2 is a cytosolic DNA sensor that assembles an inflammasome complex in innate immune signalling. Peptide competition supports accurate biomarker detection by confirming these antibodies are binding their intended target before use in diagnostic-adjacent research workflows.
Blocking Peptides for Neurodegeneration and Synaptic Protein Targets
Blocking peptides for Alpha Synuclein and Alpha SNAP. Alpha synuclein aggregation into Lewy bodies is a defining neuropathological hallmark of synucleinopathies including Parkinson's disease,1 and confirming antibody specificity against it is a standard validation step in this field. Alpha SNAP is an adaptor protein that works with NSF to disassemble SNARE complexes after membrane fusion, recycling the SNARE machinery for further rounds of vesicle trafficking, making it a target of interest in synaptic vesicle research where antibody specificity also needs to be confirmed before use.
Looking for More Validation Tools?
Blocking peptides sit alongside our positive control peptides and the wider biomolecules range for antibody and assay validation.
1. Murphy J, McKernan DP. The Effect of Aggregated Alpha Synuclein on Synaptic and Axonal Proteins in Parkinson's Disease—A Systematic Review. PMC9496556
2. Amarante-Mendes GP, Rana A, Datoguia TS, Hamerschlak N, Brumatti G. BCR-ABL1 Tyrosine Kinase Complex Signaling Transduction: Challenges to Overcome Resistance in Chronic Myeloid Leukemia. PMC8780254
3. Prihadi JC, Lionardi SK, Widjanarko ND, Alvianto S, Rinaldi FX, Iskandar AF. AMACR is a highly sensitive and specific immunohistochemical marker for diagnosing prostate cancer on biopsy: a systematic review and meta-analysis. PMC12264481
For Research Use Only. Not intended for use in diagnostic or therapeutic procedures.