• Sensitive — Accurately detects peptide mixtures as low as 5 µg/mL (fluorometric method) or 25 µg/mL (colorimetric method)
• Reproducible — The performance of the assay kit has been rigorously tested using a peptide digestion mixture
• Reliable Peptide Digestion Standard — The kit includes a validated peptide digestion standard that improves quantification of reproducible Presentability
• Compatible — Works with a variety of reagents, including MS sample preparation reagents and TMT-labeled peptides (fluorometric assays)
• Convenient — Simple The mixed reading format enables stable signals to be read in just 5 minutes (fluorescence method) or 15 minutes (colorimetric method)

Pierce Quantitative Colorimetric Peptide Detection KitModified BCA reagent (for reduction of Cu+2 to Cu+1), optimized proprietary chelating agent (for quantification of peptide mixtures), and peptide digestion reference standards (for generation of control linear standard curves) are available . This colorimetric peptide detection kit requires only a small amount of sample (20 µL) and has a working peptide concentration range of 25–1000 µg/mL. In the reaction, copper is first reduced through the amide backbone of the peptide under alkaline conditions (biuret reaction). Subsequently, the reduced copper combines with the chelate to form a bright red complex (absorption wavelength 480 nm). The complex can be read in as little as 15 minutes. This reaction produces a signal that is 3–4 times more sensitive than the Micro-BCA Protein Assay Kit for peptide analysis. Colorimetric peptide detection kits are compatible with TMT-labeled peptides, but are not recommended for use with synthetic peptides as the detection kit is affected by the amino acid content of the peptide.

Pierce Quantitative Fluorescent Peptide Detection KitThe reagents include peptide assay buffer, fluorescent peptide labeling reagents, and peptide digestion assay standards for quantitative determination of peptide concentration. This sensitive assay requires only 10 µL of sample, responds linearly with increasing peptide concentration (5–1000 µg/mL), and generates stable final fluorescence that can be detected in as little as 5 minutes. In this assay kit, a specific label is added to the amino terminus of the peptide using an amine-reactive fluorescent reagent (which does not fluoresce until reacted with tryptic peptides). Fluorescently labeled peptides were detected on a microplate reader (ex390/em475). This assay is suitable for the quantitative determination of peptide digest mixtures and synthetic peptides with unblocked amino termini. Fluorescence detection kits are not compatible with TMT-labeled peptides.

Thermo Scientific Peptide Digestion Assay StandardIntended for use as a reference standard for use with Pierce quantitative fluorescent and colorimetric peptide detection reagents to improve reproducibility of peptide quantification and accuracy. Peptide digestion assay standards are supplied in ready-to-use liquid format at a concentration of 1 mg/mL. Reference proteins have been digested with MS-grade trypsin to minimize missing cleavages. To ensure consistent performance, monitor protein digestion efficiency to ensure batch-to-batch consistency and assess quality by comparison to reference standards.

Applications
• Normalize sample concentration for downstream quantitative applications
• Normalize sample loading for LC, MS and LC/MS Applications
• Measuring recovery after peptide purification steps