Cysteine Levels Research Articles

Novel Approach for Biosensor-Based Imaging of Cysteine Levels in Ischemeic Heart Disease: Insights from Preclinical Models and Human Samples.

Cardiovascular diseases (CVDs) pose a serious threat to human health, with atherosclerosis being a leading cause of heart disease and stroke. Elevated cysteine (Cys) levels have been closely linked to an increased risk of cardiovascular diseases, underscoring its significance in cardiovascular health. However, current detection methods for cysteine in serum and atherosclerotic plaques present challenges in sensitivity, specificity, dynamic monitoring, and invasiveness. The development of more sensitive, specific, and noninvasive assays is needed to enable accurate monitoring of cysteine levels. This study introduces the development and characterization of Cys-NPs, a sensitive and selective tool for imaging cysteine in foam cells and atherosclerotic mice. Encapsulation of the HD-probe using DSPE-PEG to obtain Cys-NPs effectively reduced interference from glutathione (GSH), leading to successful preparation and validation of Cys-NPs's nanoscale structure. At the same time, Cys-NPs was able to use the differences in Hcy and Cys concentrations in vivo to better assess Cys levels in vivo. In vitro and in vivo studies demonstrated Cys-NPs's effective imaging of cysteine in foam cells and atherosclerotic mice, highlighting its potential for noninvasive assessment of cysteine levels in ischemic heart disease research and clinical practice.

Regulatory mechanism of cysteine-dependent methionine biosynthesis in Bifidobacterium longum: insights into sulfur metabolism in gut microbiota

ABSTRACT Sulfur, a critical element for bacterial growth, is not directly utilized by bifidobacteria, rendering the sulfur-containing amino acid biosynthesis pathway, particularly for cysteine and methionine, poorly understood. This research identifies six genes involved in this pathway through re-annotation of the Bifidobacterium longum DJO10A genome. These genes play crucial roles in bioconversion processes essential for cysteine utilization, highlighting its significance in sulfur metabolism. Our study uncovers a novel regulatory mechanism of these pathways under varying cysteine concentrations. We demonstrate a dual-pathway mechanism for methionine biosynthesis: one directly utilizing cysteine (trans-sulfurylation pathway) and another utilizing H2S derived from cysteine degradation (direct sulfurylation pathway). This regulatory dual-pathway mechanism is contingent on environmental cysteine levels, with both pathways activated at low cysteine levels, while higher levels predominantly engage the H2S-utilizing pathway. This investigation not only advances our understanding of DJO10A’s metabolic capabilities but also underscores the bacterium’s adaptability through sophisticated regulatory mechanisms for sulfur-containing amino acid biosynthesis. The elucidation of these pathways provides valuable insights into the survival strategies of bifidobacteria in the gut environment, where sulfur sources can vary greatly. Through detailed genomic, transcriptional, and enzymatic analyses, this study significantly contributes to the field of microbiology, offering a foundation for future research on gut microbiota metabolic pathways and their implications for host health.

Contribution of haptoglobin phenotypic variation to the presence of hyperhomocysteinemia in type 2 diabetics with and without angiopathy.

The genetic polymorphism of haptoglobin (Hp) has been associated with several cardiovascular risk factors, but a possible relationship between Hp phenotypic variation and increased levels of homocysteine (Hcy) and cysteine (Cy) is still unknown. The objective of this study is to evaluate the relationship between the Hp polymorphism and hyperhomocysteinemia (HHcy) and hypercysteinemia (HCy) in type 2 diabetics (T2D) with and without angiopathy (AGP). A case-control study was carried out on 293 adults: Group I (GI) - 75 subjects with T2D and AGP; Group II (GII) - 75 subjects with T2D without AGP; Group III (GIII) - 143 controls. Plasma levels of Hcy, Cy and vitamin B6 were measured by high performance liquid chromatography (HPLC) and vitamins B9 and B12 determined by electrochemiluminescence (ECL). The Hp polymorphism was identified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and peroxidase staining. The results were analyzed in SPSS®, version 26.0 with a significance of 95%. Mean Hcy concentrations were significantly lower in carriers of the Hp2-2 phenotype (6.14 µM; p = 0.046) compared to the other genotypes. The presence of Hp2-1 is associated with an approximately 3.3 times greater probability of occurrence of HHcy (p = 0.015) and 3.7 times greater probability occurrence of HCy (p = 0.021) in T2D with AGP. The presence of the Hp2-1 phenotype is associated with the predisposition of HHcy and HCy in individuals with T2D and AGP, possibly through a positive heterosis mechanism. Carriers of the Hp2-2 phenotype appear to have a greater activation of the transsulfuration pathway in the Hcy cycle and consequent protection for its accumulation.

Methionine-SAM metabolism-dependent ubiquinone synthesis is crucial for ROS accumulation in ferroptosis induction

Ferroptosis is a cell death modality in which iron-dependent lipid peroxides accumulate on cell membranes. Cysteine, a limiting substrate for the glutathione system that neutralizes lipid peroxidation and prevents ferroptosis, can be converted by cystine reduction or synthesized from methionine. However, accumulating evidence shows methionine-based cysteine synthesis fails to effectively rescue intracellular cysteine levels upon cystine deprivation and is unable to inhibit ferroptosis. Here, we report that methionine-based cysteine synthesis is tissue-specific. Unexpectedly, we find that rather than inhibiting ferroptosis, methionine in fact plays an essential role during cystine deprivation-induced ferroptosis. Methionine-derived S-adenosylmethionine (SAM) contributes to methylation-dependent ubiquinone synthesis, which leads to lipid peroxides accumulation and subsequent ferroptosis. Moreover, SAM supplementation synergizes with Imidazole Ketone Erastin in a tumor growth suppression mouse model. Inhibiting the enzyme that converts methionine to SAM protects heart tissue from Doxorubicin-induced and ferroptosis-driven cardiomyopathy. This study broadens our understanding about the intersection of amino acid metabolism and ferroptosis regulation, providing insight into the underlying mechanisms and suggesting the methionine-SAM axis is a promising therapeutic strategy to treat ferroptosis-related diseases.

Catabolism of extracellular glutathione supplies amino acids to support tumor growth.

Restricting amino acids from tumors is an emerging therapeutic strategy with significant promise. While typically considered an intracellular antioxidant with tumor-promoting capabilities, glutathione (GSH) is a tripeptide of cysteine, glutamate, and glycine that can be catabolized, yielding amino acids. The extent to which GSH-derived amino acids are essential to cancers is unclear. Here, we find that GSH catabolism promotes tumor growth. We show that depletion of intracellular GSH does not perturb tumor growth, and extracellular GSH is highly abundant in the tumor microenvironment, highlighting the potential importance of GSH outside of tumors. We find supplementation with GSH can rescue cancer cell survival and growth in cystine-deficient conditions, and this rescue is dependent on the catabolic activity of γ-glutamyltransferases (GGTs). Finally, pharmacologic targeting of GGTs' activity prevents the breakdown of circulating GSH, lowers tumor cysteine levels, and slows tumor growth. Our findings indicate a non-canonical role for GSH in supporting tumors by acting as a reservoir of amino acids. Depriving tumors of extracellular GSH or inhibiting its breakdown is potentially a therapeutically tractable approach for patients with cancer. Further, these findings change our view of GSH and how amino acids, including cysteine, are supplied to cells.

A Fluorescent Probe Containing Triphenylamine-Benzofuranone Moiety for Detecting Cysteine and Imaging in Living Pulmonary Cells Under Hypercapnia.

In this work, a fluorescent probe TPB-Cys derived from triphenylamine-benzofuranone was developed for monitoring the cysteine (Cys) level and imaging in living pulmonary cells under hypercapnia condition. A systematic hypoxia module was tried to cover both the in-solution test and pulmonary cellular imaging. The hypoxia condition did not obviously affect the fluorescence response signal during the in-solution test. The fluorescence signal at 540 enhanced in a dose-dependent enhancement along with the increase of the Cys concentration. The probe showed the advantages including relatively long linear range, high sensitivity, high stability, and high selectivity. With low cyto-toxicity, TPB-Cys achieved the monitoring of the endogenous Cys level in living pulmonary cells. Furthermore, it also realized the visualization of the affection of the hypoxia and hypoxia recovered conditions. This work was informative for both the accurate diagnosis and potential medical techniques.

Middle-aged dogs with low and high Aβ CSF concentrations show differences in energy and stress related metabolic profiles in CSF

BackgroundAmyloid beta (Aβ) accumulation in the brain is one of the earliest findings in Alzheimer's disease (AD). The dog is a natural animal model for amyloid processing and early brain amyloid pathology. The goal of this study is to examine which differences in metabolomic profiles in cerebrospinal fluid (CSF) could be detected in dogs with a difference in CSF Aβ concentrations before amyloid accumulation occurs. MethodMetabolic profiling was performed on CSF from 4 to 8 year old dogs with different CSF Aβ concentrations. ResultsMetabolomic profiling of CSF showed differences in brain energy metabolism. More specifically, increases in N-acetylation of amino acids and amino sugars, creatine and pentose metabolism, and a decrease in tricarboxylic acid (TCA) cycle were seen in dogs with a high CSF Aβ concentration. In addition, signs of elevated oxidative stress, higher methionine, lipid and nucleotide metabolism and increased levels of cysteine, myo-inositol and trimethylamine N-oxide were noted in these animals. ConclusionsDifferences in energy metabolism and stress mediated metabolic changes are seen in the brain of dogs with different CSF Aβ concentrations, before any amyloid deposition occurs. Similar metabolic changes, as in the high Aβ dogs, have been described in AD in humans and/or transgenic AD mice, some of them in very early phases. General significanceThe differences observed in metabolomic profiles could help in identifying potential biomarkers for an increased risk of developing amyloid pathology in the brain and open the door to the evaluation of preventive treatments for amyloid pathology in humans.

Salivary cysteine levels as a potential biochemical indicator of oral cancer risk in tobacco consumers.

Aim: Oral cancer is the leading cause of mortality, with a survival rate of less than 5 years, and is predominantly influenced by tobacco mutagens. Invasive diagnostic methods hinder early detection of oral cancer biomarkers. The present study performed salivary biochemical analysis for early oral cancer screening in tobacco consumers.Materials & methods: Three study groups included healthy controls (n=25), tobacco users (n=25) and oral cancer patients (n=25). Salivary total protein, amylase, TNF-α and amino acid levels were evaluated using enzymatic tests, Enzyme linked Immunosorbent Assay (ELISA) and High-Performance Liquid Chromatography (HPLC).Results: Compared with healthy controls, salivary total protein and TNF-αlevels were significantly (p=0.04) higher in oral cancer patients. Salivary amylase levels were significantly lower in tobacco smokers (p=0.02) and higher in oral cancer patients (p=0.01). Interestingly, the amino acid cysteine concentration was significantly higher (p=0.02) in tobacco consumers (62.5±10) than in healthy controls (116.1±28).Conclusion: In high-risk populations, such as tobacco users, salivary biochemical analysis can serve as a promising noninvasive diagnostic method for early oral cancer screening. As a salivary biomarker, the amino acid cysteine exhibits potential as a means of detecting the progression of oral cancer in individuals who consume tobacco.

Assessing the effects of N-acetyl cysteine on growth, antioxidant and immune response in tilapia (Oreochromis niloticus) under different regimes of stocking densities.

The study investigated the impact of N-acetyl cysteine on growth, immune response, and antioxidant activity in tilapia (Oreochromis niloticus). Fish were reared at three densities (1.50, 3.00, and 4.50 kg/m3) with four levels of N-acetyl cysteine supplementation (0, 2, 4, and 6 mg/kg) over 60 days. Better growth was observed at low density, but at all densities, fish fed the highest N-acetyl cysteine level (6 mg/kg) showed improved growth. Chemical composition of fish and activity of amylase, lipase and protease in all treatments were noted to be insignificant. The levels of antioxidant enzymes (catalase, superoxide dismutase and glutathione peroxidase) and cortisol in HD treatments were high as compared to LD and MD treatment. However, fish fed with N3 diet in each density treatment showed the lowest level of antioxidant enzymes as well as cortisol. Similarly, the levels of malondialdehyde were noted to be high at HD treatments as compared to that in LD and MD. Its levels were lower in fish fed with N3 diets in all density treatments. Expression of somatostatins-1 did not increase in MD and HD treatments in response to high stocking density when compared with LD treatment. However, pro-opiomelanocortin-α level was reduced after N3 diet in HD treatment and interleukin 1-β expression increased after N3 supplement in HD treatment. In conclusion, N-acetyl cysteine supplementation improved growth and antioxidant response in tilapia. The most optimum dose of N-acetyl cysteine was noted to be 6 mg/kg at high stocking, suggesting the potential role of this nutraceutical in tilapia intensive culture.

Hydrogen sulfide-mediated persulfidation regulates homocysteine metabolism and enhances ferroptosis in non-small cell lung cancer

Hydrogen sulfide (H₂S), a metabolite of the transsulfuration pathway, has been implicated in ferroptosis, a unique form of cell death caused by lipid peroxidation. While the exact mechanisms controlling ferroptosis remain unclear, our study reveals that H₂S sensitizes human non-small cell lung cancer (NSCLC) cells to this process, particularly when cysteine levels are low. Combining H₂S with cystine depletion significantly enhances the effectiveness of ferroptosis-based cancer therapy. Mechanistically, H₂S persulfidates the 195th cysteine on S-adenosyl homocysteine hydrolase (SAHH), reducing its enzymatic activity. This leads to decreased homocysteine levels, subsequently lowering cysteine and glutathione concentrations under cystine depletion conditions. These changes ultimately increase the vulnerability of NSCLC cells to ferroptosis. Our findings establish H₂S as a key regulator of homocysteine metabolism and a critical factor in determining NSCLC cell susceptibility to ferroptosis. These results highlight the potential of H₂S-based therapies to improve the efficacy of ferroptosis-targeted cancer treatments for NSCLC.

Oxidative Challenges Do Not Impact Pheomelanin-Dependent Coloration in Male Japanese Quails.

Colorful traits play an important role in animal communication. Melanin-based colorations are the most extended color traits in animals and are produced by two types of endogenous melanic pigments: eumelanins and pheomelanins, the last ones being the least studied in the context of communication. The production of pheomelanin requires a semi-essential amino acid, cysteine, which is also used for the synthesis of an important endogenous antioxidant, glutathione. Hence, it has been proposed that the synthesis of pheomelanin and glutathione may compete for the cysteine available in the organism. In that case, pheomelanic colorations are predicted to be less intense when the individual is facing an oxidative challenge, and therefore, they would provide information on the oxidative status of the bearer. Here, we experimentally evaluated this hypothesis using male Japanese quails (Coturnix japonica) as a model of study, a species with pheomelanin-based plumage in the breast and cheeks. During feather growth, individuals were exposed to one of three possible conditions: Control (saline), an endogenous oxidative challenge (Escherichia coli lipopolysaccharide injections), or an exogenous oxidative challenge (paraquat injections). Contrary to predictions, we found that: (1) Birds from the three groups exhibited less intense pheomelanic colorations in feathers after the experimental manipulation, and the magnitude of this change did not differ among groups. (2) There was no effect of the experimental treatments on the proportion reduced/oxidized glutathione, an index of oxidative status. (3) Lipid peroxidation was lower after the experimental manipulation, with birds exposed to the paraquat challenge experiencing a stronger decline than other groups. (4) Cysteine and total glutathione levels decreased after the experimental manipulation, with no differences per group in the magnitude of the decline. Taken together the results do not support the hypothesis that oxidative status plays a key role at determining the variation in the intensity of pheomelanic colorations.

Considerations for Using Neuroblastoma Cell Lines to Examine the Roles of Iron and Ferroptosis in Neurodegeneration.

Ferroptosis is an iron-dependent form of programmed cell death that is influenced by biological processes such as iron metabolism and senescence. As brain iron levels increase with aging, ferroptosis is also implicated in the development of age-related pathologic conditions such as Alzheimer's disease (AD) and related dementias (ADRD). Indeed, inhibitors of ferroptosis have been shown to be protective in models of degenerative brain disorders like AD/ADRD. Given the inaccessibility of the living human brain for metabolic studies, the goal of this work was to characterize an in vitro model for understanding how aging and iron availability influence neuronal iron metabolism and ferroptosis. First, the human (SH-SY5Y) and mouse (Neuro-2a) neuroblastoma lines were terminally differentiated into mature neurons by culturing in all-trans-retinoic acid for at least 72 h. Despite demonstrating all signs of neuronal differentiation and maturation, including increased expression of the iron storage protein ferritin, we discovered that differentiation conferred ferroptosis resistance in both cell lines. Gene expression data indicates differentiated neurons increase their capacity to protect against iron-mediated oxidative damage by augmenting cystine import, and subsequently increasing intracellular cysteine levels, to promote glutathione production and glutathione peroxidase activity (GPX). In support of this hypothesis, we found that culturing differentiated neurons in cysteine-depleted media sensitized them to GPX4 inhibition, and that these effects are mitigated by cystine supplementation. Such findings are important as they provide guidance for the use of in vitro experimental models to investigate the role of ferroptosis in neurodegeneration in pathologies such as ADRD.

Developing a vanillin-derived imidazo-pyridin-containing fluorescent probe for imaging cysteine in living pulmonary cells under oxygen supply variation

In this work, derived from vanillin and imidazo-pyridin backbone, a fluorescent probe IPV-Cys was developed for imaging the cysteine (Cys) level in living pulmonary cells under oxygen supply variation. By mimicking the oxygen supply variation in both the solution test and cellular imaging, the optical performance and imaging effect of IPV-Cys was investigated. In the solution system, the oxygen supply variation caused no impact on the reporting signals. The fluorescence reporting signal intensity at 490 nm suggested the enhancement along with the increase of the Cys concentration. The advantages of IPV-Cys included relatively high sensitivity, high stability, and high selectivity. On the basis of the low cyto-toxicity, IPV-Cys achieved the monitoring the endogenous Cys level in in living pulmonary cells and the impact of the oxygen supply variation by reporting fluorescence signals. The information here was meaningful for both the pre-clinical diagnosis and surgical techniques.

Hypoxia-induced cysteine metabolism reprogramming is crucial for the tumorigenesis of colorectal cancer

Metabolic reprogramming is a hallmark of human cancer, and cancer-specific metabolism provides opportunities for cancer diagnosis, prognosis, and treatment. However, the underlying mechanisms by which metabolic pathways affect the initiation and progression of colorectal cancer (CRC) remain largely unknown. Here, we demonstrate that cysteine is highly enriched in colorectal tumors compared to adjacent non-tumor tissues, thereby promoting tumorigenesis of CRC. Synchronously importing both cysteine and cystine in colorectal cancer cells is necessary to maintain intracellular cysteine levels. Hypoxia-induced reactive oxygen species (ROS) and ER stress regulate the co-upregulation of genes encoding cystine transporters (SLC7A11, SLC3A2) and genes encoding cysteine transporters (SLC1A4, SLC1A5) through the transcription factor ATF4. Furthermore, the metabolic flux from cysteine to reduced glutathione (GSH), which is critical to support CRC growth, is increased due to overexpression of glutathione synthetase GSS in CRC. Depletion of cystine/cysteine by recombinant cyst(e)inase effectively inhibits the growth of colorectal tumors by inducing autophagy in colorectal cancer cells through mTOR-ULK signaling axis. This study demonstrates the underlying mechanisms of cysteine metabolism in tumorigenesis of CRC, and evaluates the potential of cysteine metabolism as a biomarker or a therapeutic target for CRC.

Coumarin-aurone based fluorescence probes for cysteine sensitive in-situ identification in living cells

The quantification of cysteine (Cys) levels in the organisms holds paramount significance in biological research and disease diagnosis, which can give the correlation between abnormal Cys levels and diseases. In this study, two fluorescent probes, designated as DEA-OH and DEA-AC, featuring a coumarin-aurone backbone specifically engineered for Cys detection, were meticulously designed and synthesized. The diethylamino coumarin-aurone probe DEA-OH and the acrylate-substituted probe DEA-AC demonstrated remarkable sensitivity in detecting cysteine by means of copper displacement (DEA-OH) and acrylate hydrolysis mechanisms (DEA-AC) with fluorescence detection limits of 7.25 μM and 1.65 μM, respectively. Moreover, the fluorescence peak wavelength of the two probes displayed a linear relationship with solvent polarity in the ET (30) range of 30–65 kcal•mol−1, indicating the potential for monitoring changes in environmental polarity within this ET (30) range. The outstanding attributes exhibited by DEA-AC including superior photostability, remarkable selectivity, and swift response (kinetic rate constant: 0.00747 s−1), coupled with the exceptional anti-interference ability, have significantly broadened its scope of applications, for example detecting alterations in Cys within biological systems.

A Hydrogen Bonded Non-Porous Organic-Inorganic Framework for Measuring Cysteine in Blood Plasma and Endogenous Cancer Cell.

An imbalance in cysteine (Cys) levels in the cells and plasma has been identified as the risk indicator for various human diseases. The structural similarity of cysteine with its congener homocysteine and glutathione offers challenges in its measurement. Herein, we report a hydrogen-bonded organic-inorganic framework of Cu(II) (HOIF) for the selective detection of cysteine over other biothiols. The non-fluorescent HOIF showed 12-fold green emission in the presence of cysteine. The monomeric unit of HOIF is stabilized via intermolecular hydrogen bonds, resulting in a non-porous network structure. Non-interference from homocysteine, glutathione, and other competitive bio-analytes revealed explicit affinity of HOIF for cysteine. Fluorimetric titration showed a wide working concentration window (650 nM-800 μM) for measuring cysteine in an aqueous medium. The mechanistic investigation involving HRMS, EPR, and UV-vis spectroscopic studies revealed the decomplexation of HOIF with Cys, resulting in a fluorescence turn-on response from the luminescent ligand. Validation using a commercial dye, "Cysteine Green", confirmed the prospect of HOIF for early diagnostic purposes. Utilizing the fluorescence turn-on property of HOIF in the presence of cysteine, we measured cysteine quantitatively in the blood plasma samples. Bio-imaging of endogenous cysteine in cancer cells indicated the ability of HOIF to monitor the intracellular cysteine.

Epigenetic repression of de novo cysteine synthetases induces intra-cellular accumulation of cysteine in hepatocarcinoma by up-regulating the cystine uptake transporter xCT

BackgroundThe metabolic reprogramming of amino acids is critical for cancer cell growth and survival. Notably, intracellular accumulation of cysteine is often observed in various cancers, suggesting its potential role in alleviating the oxidative stress associated with rapid proliferation. The liver is the primary organ for cysteine biosynthesis, but much remains unknown about the metabolic alterations of cysteine and their mechanisms in hepatocellular carcinoma cells.MethodsRNA-seq data from patients with hepatocarcinoma were analyzed using the TNMplot database. The underlying mechanism of the oncogenic alteration of cysteine metabolism was studied in mice implanted with BNL 1ME A.7 R.1 hepatocarcinoma.ResultsDatabase analysis of patients with hepatocellular carcinoma revealed that the expression of enzymes involved in de novo cysteine synthesis was down-regulated accompanying with increased expression of the cystine uptake transporter xCT. Similar alterations in gene expression have also been observed in a syngeneic mouse model of hepatocarcinoma. The enhanced expression of DNA methyltransferase in murine hepatocarcinoma cells caused methylation of the upstream regions of cysteine synthesis genes, thereby repressing their expression. Conversely, suppression of de novo cysteine synthesis in healthy liver cells induced xCT expression by up-regulating the oxidative-stress response factor NRF2, indicating that reduced de novo cysteine synthesis repulsively increases cystine uptake via enhanced xCT expression, leading to intracellular cysteine accumulation. Furthermore, the pharmacological inhibition of xCT activity decreased intracellular cysteine levels and suppressed hepatocarcinoma tumor growth in mice.ConclusionsOur findings indicate an underlying mechanism of the oncogenic alteration of cysteine metabolism in hepatocarcinoma and highlight the efficacy of alteration of cysteine metabolism as a viable therapeutic target in cancer.

Ala-Cys-Cys-Ala dipeptide dimer alleviates problematic cysteine and cystine levels in media formulations and enhances CHO cell growth and metabolism

Cysteine and cystine are essential amino acids present in mammalian cell cultures. While contributing to biomass synthesis, recombinant protein production, and antioxidant defense mechanisms, cysteine poses a major challenge in media formulations owing to its poor stability and oxidation to cystine, a cysteine dimer. Due to its poor solubility, cystine can cause precipitation of feed media, formation of undesired products, and consequently, reduce cysteine bioavailability. In this study, a highly soluble cysteine containing dipeptide dimer, Ala-Cys-Cys-Ala (ACCA), was evaluated as a suitable alternative to cysteine and cystine in CHO cell cultures. Replacing cysteine and cystine in basal medium with ACCA did not sustain cell growth. However, addition of ACCA at 4 mM and 8 mM to basal medium containing cysteine and cystine boosted cell growth up to 15% and 27% in CHO-GS and CHO–K1 batch cell cultures respectively and led to a proportionate increase in IgG titer. 13C-Metabolic flux analysis revealed that supplementation of ACCA reduced glycolytic fluxes by 20% leading to more efficient glucose metabolism in CHO–K1 cells. In fed-batch cultures, ACCA was able to replace cysteine and cystine in feed medium. Furthermore, supplementation of ACCA at high concentrations in basal medium eliminated the need for any cysteine equivalents in feed medium and increased cell densities and viabilities in fed-batch cultures without any significant impact on IgG charge variants. Taken together, this study demonstrates the potential of ACCA to improve CHO cell growth, productivity, and metabolism while also facilitating the formulation of cysteine- and cystine-free feed media. Such alternatives to cysteine and cystine will pave the way for enhanced biomanufacturing by increasing cell densities in culture and extending the storage of highly concentrated feed media as part of achieving intensified bioproduction processes.

Visualizing detection of cysteine level under LPS-induced oxidative stress process using benzopyrylium-based mitochondrial-targeted NIR fluorescent probe

As an important scavenger of reactive oxygen species, cysteine (Cys) plays a crucial role in mitochondrial oxidative stress. Abnormal intracellular Cys concentration under oxidative stress leads to various diseases. Cys is also widely used in the food industry. Many vegetables and fruits are rich in Cys. Abnormal levels of Cys in the body can lead to a variety of diseases. Therefore, the design of fluorescent probe that can detect Cys quickly is particularly important in living organisms. In this work, a novel turn-on mitochondrial-targeted NIR fluorescent probe (SXNU-6) was designed for the high sensitivity and specificity of Cys based on benzopyrylium. Among them, acrylate group acted as recognition site and fluorescence quencher. With the addition of Cys, the fluorescence of SXNU-6 was gradually enhanced at 660 nm. The probe had good selectivity and high sensitivity, which could realize the detection of Cys in food samples (onion, garlic, tomato, lettuce, apple, pear, milk and bread). Also, SXNU-6 could detect both endogenous and exogenous Cys under LPS-induced oxidative stress process. This work provide a powerful tool for detecting Cys in food samples and biological systems.

Cysteine and Glutamine level in hair shaft fractures patients

Cysteine and Glutamine level in hair shaft fractures patients