l‐Cysteine metabolism and its nutritional implications

Abstract

L-Cysteine is a nutritionally semiessential amino acid and is present mainly in the form of L-cystine in the extracellular space. With the help of a transport system, extracellular L-cystine crosses the plasma membrane and is reduced to L-cysteine within cells by thioredoxin and reduced glutathione (GSH). Intracellular L-cysteine plays an important role in cellular homeostasis as a precursor for protein synthesis, and for production of GSH, hydrogen sulfide (H(2)S), and taurine. L-Cysteine-dependent synthesis of GSH has been investigated in many pathological conditions, while the pathway for L-cysteine metabolism to form H(2)S has received little attention with regard to prevention and treatment of disease in humans. The main objective of this review is to highlight the metabolic pathways of L-cysteine catabolism to GSH, H(2)S, and taurine, with special emphasis on therapeutic and nutritional use of L-cysteine to improve the health and well-being of animals and humans.

Dietary supplementation with l-glutamate and l-aspartate alleviates oxidative stress in weaned piglets challenged with hydrogen peroxide

“…Accumulating evidence has shown the beneficial and protective effects of Glu and Asp in animals under physiological and pathological conditions, because of their regulatory roles in oxidative stress, nutrition, immunity, and metabolism (Feng et al 2015;Wu et al 2014a, b;Yin et al 2015c).…”

Preinduction of heat shock protein 70 protects mice against post-infection irritable bowel syndrome via NF-κB and NOS/NO signaling pathways

“…Intestine is the main site for nutrients absorption and metabolism (Yin et al 2015c). The present study demonstrated that Trichinella spiralis infection induces intestinal dysfunction, while the nutrients' absorption and metabolism in PI-IBS model are still unclear.…”

“…The pathological mechanism is still obscure, while recent evidences suggested that low-grade inflammation and increased permeability in the intestine associate with the development of PI-IBS (Spiller and Garsed 2009;Wang et al 2014a). Intestine is the main site for amino acids absorption and metabolism and functional amino acids play important roles as metabolic intermediates in nutrition, immune response, inflammation, signaling transduction, and protein synthesis (Wu et al 2014;Yin et al 2015c). However, the amino acids' absorption and metabolism in PI-IBS model are still unclear.…”

Methionine And Antioxidant Potential

“…Mice genetically engineered to lack both TrxR1 and GR cannot reduce oxidized GSSG and are more susceptible to oxidative stress, while dietary methionine provides the cytosolic disulfide-reducing power and methionine-fueled transsulfuration supplies the necessary Cys precursor for GSH synthesis in TR/GRnull livers [23], suggesting that hepatocytes can adequately sustain cytosolic redox homeostasis pathways after adequate methionine uptake. Taurine and H 2 S also exhibit antioxidant function and has been reviewed at [2].…”

“…Met can be metabolized to cysteine (Cys) through transsulfuration pathway, which is further metabolized to glutathione (GSH), taurine, and hydrogen sulfide (H 2 S). All these metabolites exhibit antioxidant functions in various models (reviewed at [2]). More recently, Met also has been demonstrated to enhance cellular oxidative tolerance via pentose phosphate pathway (PPP) [3], which contributes to the balance of cellular reducing power and accelerates the reduction reaction of MetO and GSH oxidative product GSSH back to Met and GSH.…”