Mass spectrometric analysis of L-cysteine metabolism: physiological role and fate of L-cysteine in the enteric protozoan parasite Entamoeba histolytica.
Bottom Line: Furthermore, T4C and MT4C significantly enhanced trophozoite growth and reduced intracellular reactive oxygen species (ROS) levels when it was added to cultures, suggesting that 2-(R)-thiazolidine-4-carboxylic acids are involved in the defense against oxidative stress.We found that L-cysteine inside the cell rapidly reacts with aldehydes to form 2-(R)-thiazolidine-4-carboxylic acid.We showed that these 2-(R)-thiazolidine-4-carboxylic derivatives serve as an L-cysteine source, promote growth, and protect cells against oxidative stress by scavenging aldehydes and reducing the ROS level.
Affiliation: Department of Parasitology, National Institute of Infectious Diseases, Shinjuku, Tokyo, Japan.Show MeSH
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Mentions: It has previously been shown that T4C is oxidized by E. coli (48), rat liver mitochondria (43), and barley (49). Oxidation of T4C by purified rat liver mitochondria yielded N-formyl-cysteine as a major end product (43). T4C is first converted to 2,3-thiazoline-4-carboxylate (Fig. 4A), 2,3-thiazolidine-4-carboxylate, and then N-acetyl (or formyl or propinyl)-l-cysteine by ring opening and finally gives rise to acetate (or formate or propionate) and l-cysteine by l-proline dehydrogenase (EC 188.8.131.52) (Fig. 4A) (50). Whether an additional enzyme is required to convert N-formyl-l-cysteine to formate and l-cysteine is still not clear (50). However, it was suggested that the hydrolysis of N-formyl-l-cysteine occurs nonenzymatically (50).
Affiliation: Department of Parasitology, National Institute of Infectious Diseases, Shinjuku, Tokyo, Japan.