Analysis of Free Cysteine

Analysis of Free Cysteine

Since the introduction of 5,5 ’ -dithio-bis(2-nitrobenzoic acid), which is mentioned as Ellman’s Reagent in 1959, Ellman’s Test has become the favorite analytical assay for spectrophotometric measurement of free thiols of tested proteins, present in the aqueous solution. Creative Proteomics can provide robust Ellman’ s Test service for your research.

Because of the significance of protein sulfhydryls for maintenance of correct senior structure and conformation, chemistry is a rapidly expanding field in basic and applied bioscience. As a consequence, the quantitative measurement of -SH groups is one of the routine routine tasks in many applied disciplines where a rapid and reliable analytical method is strongly required. Electrochemical and fluorimetric assays of protein sulfhydryls are quite sensitive and reliable, but they involve long and complicated procedures (complete proteolysis, electrolysis, HPLC separation). Sensitivity and reliability can be achieved in an enzymatic method where protein sulfhydryls are at first reacted with cystamine and then released cysteamine cleaves papain-S-S-CH3, yielding active papain-SH, which can react with a fluorigenic substrate.

Compared with the electrochemical and fluorimetric assays, the spectrophotometric assays like Ellman’s test, are less sensitive, but they are rapid and simple; if the spectrophotometer is calibrated, there is no necessary for application of a parallel standard series. This makes Ellman’s assay still quite a popular method for quantification of thiols in various of protein therapeutics. Staffed with experienced analysts and technicians, Creative Proteomics can provide robust analytal assistance to you if needed.

* For Research Use Only. Not for use in diagnostic procedures.
Our customer service representatives are available 24 hours a day, 7 days a week. Inquiry
Online Inquiry

Please submit a detailed description of your project. We will provide you with a customized project plan to meet your research requests. You can also send emails directly to for inquiries.

  • Verification Code

Stay in Contact

  • 45-1 Ramsey Road, Shirley, NY 11967, USA
  • Tel: 1-631-275-3058 (USA)
  • Tel: 44-208-144-6005 (Europe)
  • Fax: 1-631-614-7828
  • Email:
© 2008-2021 Creative Proteomics. All rights reserved.