Biosynthesis of Cysteine
The synthesis of L-cysteine from inorganic sulfur is that the predominant mechanism by that reduced sulfur is incorporated into organic compounds. L-cysteineis used for macromolecule and glutathione synthesis and is the first supply of reduced sulfur in L-methionine, lipoic acid, thiamin, coenzyme (CoA), molybdopterin, and different organic molecules. sulphate and thiosulfate uptake in E. coli and serovar Typhimurium area unit achieved through one periplasmic transport system that utilizes 2 totally different however similar periplasmic binding proteins. Kinetic studies indicate that selenate and selenite share one transporter with sulphate, however molybdate additionally features a separate transport system. throughout aerobic growth, the reduction of sulfite to chemical compound is catalyzed by NADPH-sulfite enzyme (SiR), and serovar Typhimurium mutants lacking this catalyst accumulate sulfite from sulphate, implying that sulfite may be a traditional intermediate in assimilating sulphate reduction. L-Cysteine biogenesis in serovar Typhimurium and E. coli ceases virtually entirely once cells area unit adult on L-cysteine or L-cystine, due to a mix of consequence inhibition of amino acid transacetylase by L-cysteine and a factor restrictive system called the amino acid regulon, whereby genes for sulphate assimilation and alkanesulfonate utilization area unit expressed only sulfur is limiting. In vitro studies with the cysJIH, cysK, and cysP promoters have confirmed that they’re inefficient at forming transcription initiation complexes while not CysB and N-acetyl-L-serine. Activation of the tauA and ssuE promoters needs Cbl. it’s been planned that the 3 serovar Typhimurium anaerobic reductases for sulfite, thiosulfate, and tetrathionate might operate primarily in anaerobic respiration. 
Cysteine protection against X irradiation
Abstract : teams of fourteen to twenty seven male and feminine rats of the Sprague Dawley strain, advisement one hundred fifty to 250 g. and maintained on Derwood checkers with water to craving, got 800 roentgens in an exceedingly single exposure; animals of a similar sex were irradiated in pairs, one serving as management whereas the opposite was treated by injection of amino acid either one hour, before, 5 min. before, or 5 min. once exposure. neutral and unneutralised cysteine-HCl solutions were used at four completely different levels, namely, 175, 350, 575 and 875 mg. amino acid per metric weight unit. bodyweight.
Of the rats pre-treated with unneutralised amino acid eighty two per cent. survived as compared with nineteen per cent. of controls. Unneutralised cysteineHCl was equally effective at every level of administration, however the neutral preparation gave greatest protection at 875 mg. Administration of amino acid either one hour. or 5 min. before irradiation created the same reduction of mortality; injection of amino acid once exposure was ineffective. Of 126 animals that received neutral or unneutralised amino acid before irradiation seventy three per cent. survived, as compared with thirteen per cent. of 134 irradiated controls.-G. F. Davison. 
The cystatins: Protein inhibitors of cysteine proteinases
The last decade has witnessed huge progress of supermolecule inhibitors of amino acid proteinases regarding their structures, functions and biological process relationships. though they take issue in their molecular properties and biological distribution, they’re structurally connected proteins. All 3 repressive families, the stefins, the cystatins and therefore the kininogens, square measure members of identical taxonomic group. Recently determined crystal structures of chicken cystatin and human stefin B established a brand new mechanism of interaction between amino acid proteinases and their inhibitors that is basically completely different from the quality mechanism for aminoalkanoic acid proteinases and their inhibitors. 
Chemoselective and photocleavable cysteine modification of peptides and proteins using isoxazoliniums
It is of current interest to develop new approaches for economical and selective modification of aminoalkanoic acid residues on biomolecules. Here we tend to gift a comprehensive study on a recently developed isoxazolinium-mediated aminoalkanoic acid modification of peptides and proteins. employing a ratio quantity of isoxazolinium reagents generated in place from a chemical action amount of silver salts, cysteine-containing peptides may be with efficiency changed to afford product in nearly complete conversions. With the optimized conditions, free aminoalkanoic acid containing proteins HSA and BSA, yet as a site-directed mutated therapeutic macromolecule (BCArg) may be with efficiency and by selection labeled exploitation little amounts of the isoxazolinium reagents. we discover that the phenylacyl thioether linkage bearing associate acetylene moiety may be apace cleaved beneath irradiation of UV-A lightweight, giving the formation of a thioaldehyde moiety, which may be regenerate back to aminoalkanoic acid by reduction. 
Anti-ulcerogenic, Antioxidant and Mucogenic Effects of L-cysteine in Gastric Tissue of Wistar Rats
Aim: to judge the impact of L-cysteine pretreatment on nonsteroidal anti-inflammatory drug evoked ulceration in male wistar rats.
Study Design: Experimental animal study.
Place and length of Study: Department of Physiology (inflammation and duct secretion unit), school of medication, University of Ibadan, Nigeria, between Gregorian calendar month and July 2017.
Methodology: Fifty male wistar rats were used for this study and were indiscriminately divided into 2 study teams of twenty-five (25) animals every. the primary sub-group was used for the anti-ulcer studies; inhibitor enzymes (SOD and MDA), gas (NO), mean lesion score and stomachal blood flow (GBF), whereas the second sub-group was used for the stomachal mucous secretion secretion study. every sub cluster was divided into 5 teams with 5 animals per cluster as follows: lesion management, L-cysteine (100 mg/kg, three hundred mg/kg and five hundred mg/kg), antiacid (50 mg/kg). Results were analysed exploitation analysis of variance and reported as Mean ± SEM. Values were thought of important at… 
 Kredich, N.M., 2008. Biosynthesis of cysteine. EcoSal Plus, 3(1). (Web Link)
 Patt, H.M., TYEEE, E., Straube, R.L. and Smith, D.E., 1949. Cysteine protection against X irradiation. Science (Washington), 110, pp.213-214. (Web Link)
 Turk, V. and Bode, W., 1991. The cystatins: protein inhibitors of cysteine proteinases. FEBS letters, 285(2), pp.213-219. (Web Link)
 Chemoselective and photocleavable cysteine modification of peptides and proteins using isoxazoliniums
Jie-Ren Deng, Sai-Fung Chung, Alan Siu-Lun Leung, Wai-Ming Yip, Bin Yang, Man-Chung Choi, Jian-Fang Cui, Karen Ka-Yan Kung, Zhen Zhang, Kar-Wai Lo, Yun-Chung Leung & Man-Kin Wong
Communications Chemistryvolume 2, Article number: 93 (2019) (Web Link)
 Ajayi, O., S. Oluwole, F. and Dare, A. (2018) “Anti-ulcerogenic, Antioxidant and Mucogenic Effects of L-cysteine in Gastric Tissue of Wistar Rats”, Journal of Applied Life Sciences International, 19(3), pp. 1-10. doi: 10.9734/JALSI/2018/45289. (Web Link)