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Updated: May 8, 2026

Targeting Cysteine Thiols for in Vitro Site-specific Glycosylation of Recombinant Proteins
Published on: October 4, 2017
Cysteine reacts to form blue-green pigments with thiosulfinates obtained from garlic (Allium sativum L.)
Young Keum Shin1, Kyu Hang Kyung
1Department of Food Science, Sejong University, Seoul 143-747, Republic of Korea. sn502603@naver.com
Abstract:
Cysteine was found to form pigments with garlic thiosulfinates in this investigation, in contrast to previous reports. Pigments were formed only when the molar concentration ratios of cysteine to total thiosulfinates were smaller than 2:1. Cysteine does not form pigments with thiosulfinates in the same manner as other pigment-forming amino compounds because it has a sulfhydryl (SH) group. A colour reaction of cysteine with thiosulfinates is proposed where colourless disulphide-type S-alk(en)yl mercaptocysteines (SAMCs) are formed first by the SH-involved reaction between cysteine and thiosulfinates, and then SAMCs react with residual thiosulfinates to form pigments. When the cysteine to total thiosulfinate molar concentration ratio was 2:1 or greater, total thiosulfinates were consumed to form SAMCs without leaving any thiosulfinates remaining available for the following colour reactions.
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