Reduction mechanism of L-cysteine on keratin fibers using microspectrophotometry and Raman spectroscopy

✍ Scribed by Akio Kuzuhara; Teruo Hori

• Publisher: Wiley (John Wiley & Sons)
• Year: 2005
• Tongue: English
• Weight: 372 KB
• Volume: 79
• Category: Article
• ISSN: 0006-3525
• DOI: 10.1002/bip.20362

✦ Synopsis

Abstract

In order to investigate the reduction mechanism of L‐cysteine (Cys) on keratin fibers, cross‐sectional samples of virgin white human hair treated with Cys were prepared. The heterogeneous reaction between Cys and keratin fibers involving the diffusion of Cys into human hair was analyzed at the molecular level using microspectrophotometry and Raman spectroscopy. The diffusion pattern of Cys into human hair showed non‐Fickian type characteristics, thus indicating the free amino groups of electrostatically interacted with the anionic ions of the fiber surface. The disconnected relative concentration of —SS— groups at various depths of the hair samples with pH 9.0 was less than the Cys relative concentration, indicating that the reaction rate (the disconnection of —SS— groups) was slower than the diffusion rate of Cys into human hair. From these experiments, we concluded that the free amino groups of Cys electrostatically interacted with the anionic ions of the fiber surface, thereby decreasing the reaction rate (the disconnection of —SS— groups) of Cys at pH 9.0. © 2005 Wiley Periodicals, Inc. Biopolymers 79: 324–334, 2005

This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at [email protected]