L-Cysteine - Moligand™, Animal Free, for cell culture, ≥98% , CAS No.52-90-4

CAS: 52-90-4 Cat. No.: C108238 Formula: C₃H₇NO₂S Molecular Weight: 121.16 Beilstein Registry Number: 4506 EC Number: 200-158-2

GRADE & PURITY Animal Free, Moligand™, for Cell culture, ≥98%

Synonyms

H-Cys-OH | (R)-2-Amino-3-mercaptopropionic acid | (R)-(+)-Cysteine

Storage

Store at 2-8°C,Argon charged

Shipped In

Wet ice

Overview

L-Cysteine is a naturally-occurring non-essential amino acid. L-Cysteine is an activator of NMDA.
A non-essential amino acid.

Specifications

Synonyms

H-Cys-OH | (R)-2-Amino-3-mercaptopropionic acid | (R)-(+)-Cysteine

Specifications & Purity

Animal Free, Moligand™, for cell culture, ≥98%

Biochemical and Physiological Mechanisms

NMDA glutamate receptor

Storage

Store at 2-8°C,Argon charged

Shipped In

Wet ice

This product requires cold chain shipping. Ground and other economy services are not available.

Grade

Animal Free, for Cell culture, Moligand™

Purity

≥98%

Names and Identifiers

Pubchem Sid

488179950

Pubchem Sid Url

https://pubchem.ncbi.nlm.nih.gov/substance/488179950

Canonical Smiles

C(C(C(=O)O)N)S

IUPAC Name

(2R)-2-amino-3-sulfanylpropanoic acid

InChIKey

XUJNEKJLAYXESH-REOHCLBHSA-N

INCHI

1S/C3H7NO2S/c4-2(1-7)3(5)6/h2,7H,1,4H2,(H,5,6)/t2-/m0/s1

Isomeric SMILES

C([C@@H](C(=O)O)N)S

Molecular Weight

121.16

Beilstein

4506

Reaxy-Rn

1721406

Reaxys-RN_link_address

https://www.reaxys.com/reaxys/secured/hopinto.do?context=S&query=IDE.XRN=1721406&ln=

Taxonomic Classification

Taxonomy Tree

• Kingdom Organic compounds
  • Superclass Organic acids and derivatives
    • Class Carboxylic acids and derivatives
      • Subclass Amino acids, peptides, and analogues
        • Level5 Amino acids and derivatives
          • Level6 Alpha amino acids and derivatives
            • Level7 Cysteine and derivatives

• Kingdom: Organic compounds
• Superclass: Organic acids and derivatives
• Class: Carboxylic acids and derivatives
• Subclass: Amino acids, peptides, and analogues
• Intermediate Tree Nodes: Amino acids and derivatives - Alpha amino acids and derivatives
• Direct Parent: Cysteine and derivatives
• Alternative Parents: L-alpha-amino acids Amino acids Monocarboxylic acids and derivatives Carboxylic acids Alkylthiols Organopnictogen compounds Organic oxides Monoalkylamines Hydrocarbon derivatives Carbonyl compounds
• Molecular Framework: Aliphatic acyclic compounds
• Substituents: Cysteine or derivatives - Alpha-amino acid - L-alpha-amino acid - Amino acid - Alkylthiol - Carboxylic acid - Monocarboxylic acid or derivatives - Organic oxygen compound - Primary amine - Organosulfur compound - Organooxygen compound - Organonitrogen compound - Organic nitrogen compound - Primary aliphatic amine - Carbonyl group - Amine - Hydrocarbon derivative - Organopnictogen compound - Organic oxide - Aliphatic acyclic compound
• Description: This compound belongs to the class of organic compounds known as cysteine and derivatives. These are compounds containing cysteine or a derivative thereof resulting from reaction of cysteine at the amino group or the carboxy group, or from the replacement of any hydrogen of glycine by a heteroatom.
• External Descriptors: Common amino acids

Data sources

1. Djoumbou Feunang Y, Eisner R, Knox C, Chepelev L, Hastings J, Owen G, Fahy E, Steinbeck C, Subramanian S, Bolton E, Greiner R, and Wishart DS. ClassyFire: Automated Chemical Classification With A Comprehensive, Computable Taxonomy. Journal of Cheminformatics, 2016, 8:61.

DOI: 10.1186/s13321-016-0174-y

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Mechanisms of Action

Chemical and Physical Properties

• Solubility: H2O: 25 mg/mL；Soluble in water, alcohol, acetic acid and aqueous ammonia. Insoluble in ether, acetone, ethyl acetate, benzene, carbon disulfide and carbon tetrachloride
• Sensitivity: Light & Air sensitive
• Specific Rotation[α]: 8.8 ° (C=8, 1mol/L HCl)
• Melt Point(°C): 220°C
• Molecular Weight: 121.160 g/mol
• XLogP3: -2.500
• Hydrogen Bond Donor Count: 3
• Hydrogen Bond Acceptor Count: 4
• Rotatable Bond Count: 2
• Exact Mass: 121.02 Da
• Monoisotopic Mass: 121.02 Da
• Topological Polar Surface Area: 64.300 Ų
• Heavy Atom Count: 7
• Formal Charge: 0
• Complexity: 75.300
• Isotope Atom Count: 0
• Defined Atom Stereocenter Count: 1
• Undefined Atom Stereocenter Count: 0
• Defined Bond Stereocenter Count: 0
• Undefined Bond Stereocenter Count: 0
• The total count of all stereochemical bonds: 0
• Covalently-Bonded Unit Count: 1

Application Protocols

Note: The following are general research protocols commonly used with L-cysteine. They are not item-specific validated procedures.

1. Cell-culture stock solution (research use)

• Prepare 100× stock (e.g., 100 mM): Dissolve 1.21 g L-cysteine in water to 100 mL.
• Adjust pH to 7.0–7.4 with NaOH/HCl as needed.
• Optional: Add 0.5 mM EDTA.
• Sterile filter (0.22 µm), aliquot, flush headspace with argon, and store at 2–8 °C. Use within 1–2 weeks; prepare fresh if discoloration/precipitation occurs.

2. Reducing buffer for protein work

• 50 mM phosphate, 150 mM NaCl, 1–5 mM L-cysteine, pH 7.4.
• Degas buffer; prepare fresh before use. Monitor free thiol with Ellman’s reagent if required.

3. S-alkylation labeling (e.g., with N-ethylmaleimide)

• Dissolve protein/peptide in 50 mM HEPES, pH 7.5; add L-cysteine to pre-reduce disulfides if needed, then remove excess (desalting).
• Add maleimide reagent (1.2–2 equiv per cysteine), react 15–60 min at RT, quench with excess cysteine or other thiol scavenger.

4. Refolding with redox couple

• 50 mM Tris, 2 mM reduced L-cysteine and 0.2 mM cystine, pH 8.0; adjust ratios to tune redox potential.

Always verify compatibility with your system. For cell-based work, ensure sterility and consider oxygen control to limit cysteine oxidation.

Biological Roles

General biochemical context (literature)

• Proteinogenic amino acid: L-Cysteine is incorporated into proteins and contributes to structural stability via disulfide bridges (cystine) and to catalytic function at enzyme active sites (nucleophilic thiolate).
• Redox homeostasis: Serves as a precursor to glutathione (GSH), a central cellular antioxidant; cysteine availability can influence redox buffering capacity in cells.
• Metal homeostasis: The thiol coordinates soft metals (e.g., Zn2+, Cu+), contributing to metalloprotein structure and metal trafficking.
• Post-translational modifications: Subject to S-nitrosylation, S-palmitoylation, and disulfide exchange, modulating protein activity and localization.
• Metabolic pathways: Intersects with sulfur metabolism (cystathionine β-synthase/β-lyase pathways), taurine synthesis, and cofactor biogenesis (e.g., iron–sulfur clusters).

Relevance to lab use (aligned with Product Data: for cell culture)

• Media component: Used to formulate defined/serum-free media; often requires careful control of oxidation state and concentration.
• Reducing environment: Helps maintain thiol-dependent enzyme activity in vitro; can mitigate oxidative stress in certain cell-culture workflows (research use only).

Notes

• No medical or clinical claims are made. The above describes basic biochemical roles and common research contexts.
• Exact biological performance characteristics for this item (e.g., endotoxin/bioburden limits) are Not specified for this item; refer to CoA/Spec Sheet.

Buffer Applications

Scope: L-Cysteine is not itself a buffering agent in the classical sense (limited buffering capacity near its pKa values and narrow practical ranges). However, it is frequently used as a functional additive to buffers.

Typical uses in buffers (literature/practice)

• Reducing additive: 0.1–10 mM L-cysteine is added to phosphate, HEPES, or Tris buffers to maintain a reducing environment, protect protein thiols, or facilitate enzymatic assays.
• Disulfide chemistry: Inclusion of cysteine/cystine pairs can set defined redox potentials for protein refolding. For example, 1–5 mM cysteine with 0.1–0.5 mM cystine in 50 mM Tris, pH 7.5–8.5 (optimize per protein).
• Ligation chemistry: In native chemical ligation buffers (e.g., 6 M guanidine·HCl, 100 mM phosphate, pH ~7), cysteine residues participate directly in the ligation mechanism.

Practical tips

• Degas buffers and maintain inert headspace (argon) to limit oxidation (consistent with Product Data storage guidance).
• Add 0.1–1 mM EDTA to chelate trace metals that catalyze oxidation.
• Prepare fresh; store aliquots at 2–8 °C and protect from air; discard if turbidity (cystine precipitation) or significant pH drift occurs.

Item-specific note

• No item-specific buffer recipes, pH ranges, or validated concentrations are provided in the Product Data; consult the CoA/Spec Sheet and adapt to your application.

Green Alternatives

Perspective: L-Cysteine is a naturally occurring, biodegradable amino acid. As a reducing agent or thiol source, it can be a greener alternative to stronger, more odorous, or less biocompatible reagents.

Comparison of reductants (literature-based, general)

• L-Cysteine
  • Pros: Biogenic, readily biodegradable; compatible with cells/enzymes; aqueous systems; low odor.
  • Cons: Oxidation-prone; weaker reducing power than DTT/TCEP; stability challenges in air.
• DTT (dithiothreitol)
  • Pros: Strong reductant; predictable behavior; works at neutral pH.
  • Cons: Derived from petrochemicals; odor; less biocompatible at higher concentrations; more hazardous classifications.
• TCEP (tris(2-carboxyethyl)phosphine)
  • Pros: Strong, air-stable, odorless; effective across pH range; does not contain sulfur.
  • Cons: Synthetic phosphine; potential aquatic toxicity; less biodegradable; may interfere with downstream chemistries.
• β-Mercaptoethanol (BME)
  • Pros: Effective reductant; inexpensive.
  • Cons: Strong odor; volatility; occupational exposure concerns; less suitable for open handling.

Greener handling strategies for L-cysteine

• Use argon-charged containers (as per Product Data) and prepare minimal, fresh solutions to reduce waste from oxidation.
• Employ catalytic regeneration (e.g., small amounts of DTT/TCEP only where necessary) and recover/neutralize leftover thiols responsibly.
• Favor aqueous media and avoid unnecessary organic co-solvents; optimize pH to reduce excess usage.

Pharmaceutical Uses

Context (general, non-clinical; no therapeutic claims)

• Excipient/processing aid: L-Cysteine is used industrially as a processing aid and as an antioxidant/reducing component in certain bioprocess media and formulations (e.g., to control disulfide formation, adjust redox state, or aid protein folding during manufacturing research).
• Component of chemically defined media: Common in upstream bioprocess development for mammalian and microbial systems where precise amino acid control is required (research use only).
• Complexation/chelation roles: Its thiol and amine groups can chelate trace metals, influencing stability of actives sensitive to metal-catalyzed oxidation.

Formulation considerations (literature)

• Stability: Susceptible to air oxidation (cystine formation), especially at neutral–alkaline pH; inert headspace and metal chelators mitigate degradation.
• pH and ionic strength: Solubility and ionization state vary with pH; buffers around pH 6–7 often balance stability with compatibility.
• Compatibility: Can react with electrophiles (e.g., aldehydes via thiazolidines, maleimides via Michael addition); evaluate excipient interactions.

Item-specific limitations

• This product is designated “Animal Free, Moligand™, for Cell culture.” Specific pharmacopeial status (e.g., USP/EP), assay limits, or residual solvent/metal specifications are Not specified for this item; refer to CoA/Spec Sheet.
• For research use only (per Product Data); not for human or veterinary use.

Physical Properties

Note: Values below are literature/typical references for L-cysteine; they are not item-specific specifications.

• Appearance: Not specified for this item; refer to CoA/Spec Sheet.
• Molecular formula and mass: C3H7NO2S; 121.16 g/mol (literature)
• Acid–base properties (literature):
  • pKa1 (–CO2H) ≈ 1.9–2.0
  • pKa2 (–SH) ≈ 8.3–8.5
  • pKa3 (–NH3+) ≈ 10.2–10.3
  • Isoelectric point (pI) ≈ 5.0–5.1
• Solubility (literature):
  • Water (25 °C): high (on the order of 25–30 g/100 mL depending on ionic strength and pH)
  • Practically insoluble in nonpolar solvents (e.g., diethyl ether); sparingly soluble in ethanol/methanol.
• Melting point (literature): ~240–250 °C (decomposition; varies by hydration/crystal form)
• Optical rotation (literature, example): [α]D typically negative for L-form in water; exact value depends on concentration/temperature.
• Partitioning (literature): Highly polar, logP << 0; exists as zwitterion near neutral pH.
• Hygroscopicity/oxidation: The thiol can oxidize to cystine in air/solution (literature observation).

For authoritative, lot-specific data (e.g., water content, residual metals, UV cutoff), consult the CoA/Spec Sheet. No item-specific physical constants were provided in the Product Data.

Quality & Grades

Item-specific (from Product Data)

• Grade/Purity: Animal Free, Moligand™, for Cell culture

What this typically implies (general guidance; not a guarantee for this specific lot)

• Animal Free: Manufactured without animal-derived materials, reducing risk of adventitious agents and aligning with regulatory and ethical expectations for cell culture and bioproduction workflows.
• For Cell culture: Indicates suitability for use as a media component or supplement in research cell culture applications. Usually entails tighter controls on bioburden, endotoxin, and trace contaminants compared with commodity grades. Exact limits are Not specified for this item; refer to CoA/Spec Sheet.
• Moligand™: Branded designation suggesting ligand/metal-binding relevance or specialized use in complex biological media. Practically, L-cysteine is a known soft ligand (thiol) for transition metals; the brand may highlight consistency in ligand functionality. Specific program attributes are Not specified for this item; refer to CoA/Spec Sheet.

What is not included unless stated on CoA/Spec Sheet

• Specific assay purity %, metals profile, bioburden/endotoxin limits, water/peroxide content, optical rotation range, and UV profile are Not specified for this item; refer to CoA/Spec Sheet.

Why grade matters in practice

• In chemically defined or serum-free media, trace metals and peroxides can impact cell performance and cysteine stability. Selecting a cell-culture grade helps minimize variability, while inert-atmosphere packaging (argon charged; Product Data) helps preserve thiol integrity by limiting oxidation.

Reaction & Applications

Highlights (general chemistry; expand-on applications)

• Redox chemistry: The thiol undergoes reversible oxidation to cystine (disulfide). Employed as a mild, biologically compatible reductant (e.g., maintaining reducing environments in cell culture/media or refolding buffers).
• Nucleophilic thiol reactions: Participates in S-alkylation (with haloacetamides, maleimides), thiol–ene/thiol–yne additions (radical or Michael-type to electron-deficient alkenes), and disulfide exchange.
• Peptide/bioconjugation: Serves as a handle for site-selective conjugation via the cysteine residue; used in native chemical ligation (NCL) where N-terminal cysteine reacts with thioesters to form native amide bonds.
• Ligand/chelation chemistry: The thiol and amine act as soft/hard donor sites for transition-metal coordination (e.g., Cu, Zn, Pd), relevant to catalytic systems and to controlling trace metal speciation in media.
• Chiral building block: L-Cysteine’s stereocenter and thiol enable access to a variety of chiral auxiliaries, thiazolidines, and sulfur-containing pharmaceuticals/intermediates (general literature utility; no therapeutic claims).

Practical tips

• Maintain reducing conditions (e.g., argon headspace, degassed solvents, EDTA 0.1–1 mM) to suppress oxidative dimerization.
• Control pH: Thiolate formation (pH > pKa,SH ~8.3) dramatically increases nucleophilicity but also risks side reactions (air oxidation, over-alkylation). Work quickly or at lower temperatures when high reactivity is not desired.
• For NCL: Use buffered aqueous/organic media (e.g., 6 M guanidine·HCl, phosphate, pH ~7) with thiol catalysts as needed; monitor by LC-MS.

Reaction Conditions

General guidance (literature; adapt to your system)

1. S-Alkylation (e.g., iodoacetamide labeling)

• Solvent: Aqueous buffer (50–100 mM phosphate or HEPES), pH 7.5–8.5
• Temperature: 0–25 °C
• Stoichiometry: Electrophile 1.1–2.0 equiv vs thiol
• Time: 10–60 min (monitor by LC/MS)
• Notes: Maintain inert atmosphere; add 0.5–2 mM EDTA; avoid excess base to limit over-alkylation.

2. Disulfide formation/exchange

• Solvent: Aqueous buffer, pH 7–8
• Oxidants: Air/O2 (slow), mild oxidants (e.g., diamide) if needed
• Temperature: 4–25 °C
• Time: 0.5–24 h depending on conditions
• Notes: Control redox by adding defined cysteine/cystine ratios; monitor by Ellman’s assay or HPLC.

3. Native Chemical Ligation (NCL)

• Solvent: 6 M guanidine·HCl in 100 mM phosphate or acetate buffer
• pH: ~7.0–7.5
• Additives: Thiol catalysts (e.g., MPAA 20–50 mM)
• Temperature: 20–37 °C
• Time: 2–24 h
• Notes: Degas thoroughly; maintain reducing environment to keep cysteine in thiol state.

4. Thiol–Michael addition (to maleimides/acrylates)

• Solvent: Aqueous or mixed aqueous/organic (e.g., 50 mM phosphate with 10–30% acetonitrile)
• pH: 7–8.5 (thiolate formation; balance with selectivity)
• Temperature: 0–25 °C
• Time: 5–120 min
• Notes: Avoid excess base; quench/neutralize upon completion.

These are literature-style ranges for planning; optimize empirically. No item-specific validated conditions are provided in the Product Data.

Safety & Handling

GHS/SDS

• GHS classification, signal word, H-statements, pictograms: Not specified for this item; consult the product SDS for authoritative safety information.

General laboratory safety (literature/good practice)

• L-Cysteine is generally of low acute toxicity but may cause irritation to eyes, skin, and respiratory tract as a dust. Avoid inhalation and contact.
• PPE: Wear lab coat, safety glasses, and appropriate gloves (e.g., nitrile). Use in a fume hood when weighing powders or preparing solutions.
• Incompatibilities: Strong oxidizers (thiol oxidation); nitrosating agents (S-nitrosothiol formation); metals/metal salts may catalyze oxidation. Avoid prolonged exposure to air; argon/nitrogen headspace is beneficial (aligned with Product Data: argon charged).
• Special risks: Thiol groups can oxidize to cystine; solutions may change over time, especially at neutral–alkaline pH and in the presence of dissolved oxygen or trace metals.

First-aid overview (consult SDS for details)

• Inhalation: Move to fresh air; seek medical advice if symptoms persist.
• Skin/eye contact: Rinse with water for several minutes; remove contaminated clothing; seek medical attention if irritation develops.
• Ingestion: Rinse mouth; do not induce vomiting; seek medical advice.

Waste/Spill

• Small spills: Avoid dust formation; sweep with minimal agitation and dispose per institutional and local regulations.
• Disposal: Aqueous solutions can be collected and disposed of as nonhalogenated aqueous organic waste unless local rules require otherwise.

Solvent Selection

Context: L-Cysteine is a zwitterionic, highly polar amino acid. Solvent choices are driven by intended use (e.g., media supplementation, bioconjugation, protein chemistry) and desired protonation state.

General solubility/miscibility profile (literature)

• Highly soluble in water; solubility increases in the presence of counter-ions and at extremes of pH where net charge increases.
• Sparingly soluble in lower alcohols; essentially insoluble in nonpolar organics (e.g., ethers, hydrocarbons).

Practical selection guidance

• Aqueous buffers: Most applications use purified water or defined buffers (e.g., phosphate, HEPES) at pH 6–8. Include metal chelators (e.g., 0.1–1 mM EDTA) if oxidation is problematic.
• Alkaline dissolution: Briefly adjusting to pH 8–9 (with NaOH) increases solubility and provides thiolate for nucleophilic chemistry; immediately neutralize if required to limit side reactions.
• Mixed aqueous-organic: For peptide ligation or thiol-ene chemistry, 10–50% v/v water-miscible organic co-solvent (e.g., acetonitrile, DMF) can be used; keep water content sufficient to maintain cysteine solubility.
• Degassing/inerting: Deoxygenate solutions (argon/N2 sparge) and use argon headspace to minimize oxidation to cystine (aligns with Product Data: argon charged storage).

Comparison (use-case driven)

• L-Cysteine vs DTT/BME (reducing agents): Cysteine is less odorous than BME and more biocompatible in media, but weaker/more oxidation-prone than DTT; choose based on required reducing strength and downstream compatibility.

Storage & Reconstitution

Item-specific (from Product Data)

• Storage conditions: Store at 2–8 °C, Argon charged.
• Shipping: Wet ice.

General best practices (literature/good laboratory practice)

• Protect from air and moisture: The thiol can oxidize to cystine; keep containers tightly sealed with inert (argon) headspace (aligns with Product Data).
• Light/temperature: Store refrigerated (2–8 °C). Avoid freeze–thaw cycling of solutions unless aliquoted.
• Hygroscopic/oxidation: Minimize time at ambient conditions when weighing; promptly recap and purge with argon.

Reconstitution guidance (aqueous use)

• Water quality: Use freshly degassed, deionized water (or buffer). Optionally include 0.1–1 mM EDTA to suppress metal-catalyzed oxidation.
• Concentration: Common stocks are 10–500 mM depending on application. Adjust pH to 6.5–7.5 for general media use, or to 8–9 to increase thiolate for specific chemistries.
• Sterilization: 0.22 µm filter sterilize for cell-culture applications; avoid autoclaving solutions (promotes oxidation/degradation).
• Aliquoting: Dispense into inert-gassed, amber vials; minimize headspace; store at 2–8 °C. For longer storage, freeze aliquots at −20 °C under inert gas if compatible with your workflow.

Shelf-life and specifications

• No item-specific shelf-life, assay, or stability specifications are provided; Not specified for this item—refer to CoA/Spec Sheet.
• Inspect solutions for turbidity or yellowing (indicative of oxidation/byproducts); prepare fresh if changes are observed.

Research Use Only: Per Product Data, this product is for research use only.

Structure & Identity

Brief overview: L-Cysteine is the L-enantiomer of the sulfur-containing α-amino acid cysteine, featuring a thiol side chain (–CH2–SH), a primary amine, and a carboxylic acid on the α-carbon.

Item-specific (from Product Data)

• SKU: C108238
• Product name: L-Cysteine
• CAS: 52-90-4
• PubChem CID: 5862
• Grade/Purity: Animal Free, Moligand™, for Cell culture
• Storage: Store at 2–8°C, Argon charged; shipped on wet ice
• Category: 生命科学 (Life Science)
• InChIKey (as provided): 427557

Literature identity (general reference; not item-specific)

• IUPAC name: 2-amino-3-sulfanylpropanoic acid (L-configuration)
• Molecular formula: C3H7NO2S (literature)
• Molecular weight: 121.16 g/mol (literature)
• Canonical SMILES: NC@@HC(=O)O (literature; L-stereochemistry)
• Key functional groups: α-amino (–NH2/–NH3+), carboxyl (–CO2H/–CO2−), thiol (–SH)
• Stereochemistry: One stereocenter at the α-carbon (S-configuration for L isomer)

2D structural description (general)

• Backbone: A three-carbon chain with the α-carbon bearing an amino and carboxylate group; the β-carbon bears a thiomethyl (–CH2–SH) substituent.
• Zwitterionic at neutral pH: –NH3+ and –CO2− predominating; thiol protonation depends on pH (pKa,SH ~8–9, literature).
• Capable of intramolecular and intermolecular hydrogen bonding; thiol group participates in redox chemistry (disulfide formation).

Synthetic Utility

Functional group portfolio

• Thiol (–SH): Enables S-alkylation/arylation, thiol–ene and thiol–Michael additions, and reversible disulfide formation. Useful handle for site-selective modification and protecting-group strategies (e.g., formation of thiazolidines with aldehydes/ketones).
• α-Amino acid motif: Allows peptide coupling (amide bond formation) and chiral induction; L-configuration provides stereocontrol in auxiliary-based syntheses.

Named/representative transformations (literature)

• Native chemical ligation (NCL): N-terminal cysteine reacts with thioesters to form native amide bonds under aqueous conditions.
• Disulfide stapling/exchange: Access to cystine or mixed disulfides for protein crosslinking or dynamic covalent chemistry.
• S-alkylation with haloacetamides/maleimides: Selective conjugation to install probes, PEG chains, or handles for further diversification.
• Thiazolidine formation: Protection of cysteine’s amine/thiol by condensation with aldehydes; reversible under mild acid.

Retrosynthetic value

• Acts as a chiral synthonic unit to introduce sulfur-containing stereocenters; conversion to derivatives (e.g., sulfoxides, sulfones) expands polarity/reactivity space.

Practical notes

• Control pH to favor thiolate for S-alkylation (pH 8–9) while minimizing undesired oxidation; include EDTA and work under inert atmosphere.
• For peptide couplings, protect thiol (e.g., Acm, Trt, tBu) to avoid side reactions; deprotect under conditions compatible with the sequence.

Target Specificity

Not applicable. This product is a small-molecule amino acid, not an antibody, protein, or targeted biological. No antigen/epitope, clone, isotype, or species reactivity applies. For functional selectivity in chemistry (e.g., thiol-selective conjugation), refer to “Reaction & Applications” and “Synthetic Utility.”

Frequently Asked Questions

What is the purity of this product?

This product is supplied at ≥98% purity (chemical assay). Lot-specific values are stated on the Certificate of Analysis.

What is Moligand??

Moligand? is one of Aladdin Scientific's premium product lines, formulated for high-purity applications across multiple workflows. Compared to standard grades in the same workflow, Moligand? products typically offer tighter specifications, more rigorous QC, and stronger lot-to-lot consistency.

What does Animal Free mean?

Animal Free indicates that the material has been processed and tested for specialty industrial processing. Specifications focus on the impurities that affect performance in that application — for example, metal content for electronics, particle size for batteries, refractive index for optics, or moisture content for moisture-sensitive processes.

How should this product be stored?

Store at 2–8 °C under argon. It is supplied under an argon blanket; reseal under inert gas after each use.

How is this product shipped?

This product ships chilled on wet ice. Unpack on arrival and transfer it to the storage condition stated above.

What are the CAS number, molecular formula and molecular weight?

The CAS Number is 52-90-4, the molecular formula is C3H7NO2S, and the molecular weight is 121.16 g/mol. InChIKey XUJNEKJLAYXESH-REOHCLBHSA-N.

What documentation is provided?

Available product documentation, including Certificates of Analysis (COA), Safety Data Sheets (SDS), and specification sheets, is shown in the product document area. Document availability and access follow the current site policy.