• Catalog Number K005-F
  • Assay Type Detection Kit
  • Sample Types Buffers
  • Sensitivity 4.62 nM
  • Species Identical across all species
  • Assay Duration 30 Minutes
  • Samples/Plate 39 in Duplicate
  • Readout Fluorescent, 510 nm emission / 370-410 nm excitation


Assay Principle:

The DetectX® Thiol Fluorescent Detection Kit accurately measures free thiol levels in buffers, offering a quick 30 minute run time. To ensure proper execution of the assay,  refer to the detailed instructions in the kit insert. This kit includes an N-Acetylcysteine standard to create a precise standard curve.

Protocol Summary:

  • Place standards or diluted samples into the black microtiter plate.
  • Mix in ThioStar® Detection Reagent to each well for uniform reaction.
  • Incubate at room temperature for 30 minutes, allowing the fluorescent reaction between the ThioStar® Detection Reagent and free thiols.
  • Use a plate reader post-incubation to measure the fluorescent signal and determine free thiol concentration from the standard curve.


Free thiols, particularly in the form of cysteine residues in proteins, are important in biological systems. The modification of these thiol groups can affect protein activity, necessitating accurate measurement of such changes. Detecting modifications in complex protein samples, especially in the presence of agents like guanidine hydrochloride, is challenging with traditional methods like Ellman’s reagent due to their limited sensitivity.

The DetectX® Thiol Fluorescent Detection Kit is designed to overcome these challenges by offering improved sensitivity for detecting free SH groups. It is useful in research that examines protein function and modifications or whenever accurate thiol quantification is required. The kit’s methodology and reagents provide a reliable means to detect free thiols, aiding in the exploration of protein chemistry and cell processes that involve thiol dynamics.

Additionally, in the field of pharmaceutical research, understanding thiol dynamics is important for drug development. This is particularly true for medications targeting enzymes or proteins with critical thiol groups. This kit’s precision and sensitivity make it a valuable tool for pharmacological studies and in assessing the impact of drugs on thiol-modified proteins.

This kit facilitates the measurement of free thiol levels, supporting research in areas such as oxidative stress, enzymatic activity, and cellular signaling. Its effective and sensitive detection system makes it a valuable resource for researchers studying molecular biology and related fields.


Thiol Fluorescent Detection Kit


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The DetectX® Thiol Fluorescent Detection Kit allows users to accurately determine free thiol content in samples using a proprietary substrate, ThioStar®, that is converted to a brightly fluorescent product by reacting with thiols in the sample.

SKU: K005-F1 Category:

Research Areas