Ac-Cys-NHMe , CAS No.10061-65-1

CAS: 10061-65-1 Cat. No.: A1448726 Summenformel: C₆H₁₂N₂O₂S Molekulargewicht: 176.24

Storage

Store at -20°C

Shipped In

Ice chest + Ice pads

Übersicht

Ac-Cys-NHMe is a Cys dipeptide with thiol group.

Specifications

Storage

Store at -20°C

Verschickt in

Ice chest + Ice pads

Dieses Produkt erfordert Kühlkettenversand. Grundversand und andere Economy-Optionen sind nicht verfügbar.

Namen und Kennungen

Molekulargewicht

176.24

Application Protocols

No item-specific, validated protocols are supplied. The following literature-style examples illustrate typical uses of cysteine thiols; adapt to your system and consult primary references.

Example A: Maleimide conjugation

• Dissolve Ac-Cys-NHMe in degassed phosphate buffer (50 mM, pH 7.0) at 1–5 mM; include 1 mM EDTA.
• Prepare a solution of maleimide-functional partner in buffer or buffer/MeCN.
• Mix at 1.05–1.2 equiv maleimide per thiol; react at RT for 30–60 min.
• Quench residual maleimide with excess cysteine or mercaptoethanol; analyze by LC-MS.

Example B: S-alkylation with iodoacetamide

• Prepare 50 mM HEPES, pH 8.0, degassed; add Ac-Cys-NHMe to 1–2 mM.
• Add 1.1 equiv iodoacetamide; react at RT for 1 h protected from light.
• Quench with excess thiol (e.g., DTT) if needed; purify by reversed-phase HPLC.

Example C: Disulfide formation (air oxidation)

• Dissolve at 1–5 mM in 50 mM phosphate, pH 7.4; gently aerate or stir under air for 2–6 h.
• Monitor by LC-MS for disulfide dimer formation; remove oxygen to halt reaction when complete.

These are general guidelines; optimize concentrations, pH, and time for your specific system.

Biological Roles

General biochemical context (literature/general)

• Cysteine’s thiol participates in redox chemistry, metal coordination, enzyme catalysis (e.g., cysteine proteases), and structural disulfides in proteins.
• Terminal capping (N-acetyl, C-methylamide) yields a neutral, zwitterion-free mimic that approximates a cysteine residue embedded within peptides, removing complications from ionizable termini. This can be useful for studying intrinsic thiol reactivity or microenvironment effects.
• Redox behavior: The thiol can undergo reversible oxidation to disulfides and higher sulfur oxoforms (sulfenic, sulfinic) under strong oxidants; in controlled settings, this models protein thiol chemistry.

Research uses

• Probe molecule for benchmarking thiol-selective reagents (maleimides, iodoacetamides) and for calibrating assays quantifying free thiols (e.g., DTNB/Ellman’s test) without confounding amine/carboxyl reactivity.
• Model for understanding pKa shifts and nucleophilicity changes due to local hydrogen bonding or polarity, as occurs in enzyme active sites.

Note: No medical or clinical claims are made. This product is intended strictly for research use, as stated by the manufacturer.

Buffer Applications

Not typically applicable. Ac-Cys-NHMe is not a buffering agent and does not constitute a defined buffer system. For experimental work involving this compound, select buffers that support thiol stability (e.g., neutral pH, degassed, metal-chelated), as discussed under Solvent Selection and Reaction Conditions.

Green Alternatives

Context: This product is a small amino acid derivative, not a bulk solvent or reagent with straightforward “green replacement.” Greenness focuses on solvent choice and minimizing redox waste.

Greener practice options (literature/general)

• Prefer water or aqueous buffers as primary media when compatible; avoid excess organic cosolvents.
• If an organic solvent is required, consider bio-based or lower-toxicity options (e.g., ethanol) instead of DMF/DMF-like solvents, where feasible.
• Use catalytic, mild oxidants for disulfide formation (air/O2 under controlled conditions) instead of stoichiometric halogen oxidants.
• Minimize protecting-group steps by leveraging the inherent selectivity of thiol reactions at neutral pH.

Illustrative comparison (general)

• DMF vs ethanol/water: DMF offers superior solvating power for some electrophiles but carries higher EHS concerns; ethanol/water blends reduce hazard and simplify waste, albeit sometimes at the cost of solubility/reactivity.

Waste reduction

• Employ micro-scale optimization with this small model compound before scaling to valuable biomolecules, reducing material and solvent consumption.

Pharmaceutical Uses

This product is supplied for research use only. It is not an excipient or API grade material.

General formulation context (literature/general)

• N-acetylated amino acid amides can serve as model compounds in preformulation studies (e.g., thiol stability, conjugation chemistry) but are not standard pharmacopeial excipients.
• If incorporated into experimental delivery systems or conjugates, any downstream use would require full qualification and regulatory assessment beyond the scope of this catalog item.

No pharmacopeial status, compendial tests, or clinical formulation claims are provided for this item.

Physical Properties

Item-specific properties

• Appearance: Not specified for this item; refer to CoA/Spec Sheet.
• Melting point: Not specified for this item; refer to CoA/Spec Sheet.
• Boiling point: Not applicable (decomposes before boiling; peptide-like solids; literature/generic note).
• Density: Not specified for this item; refer to CoA/Spec Sheet.
• Solubility: Not specified for this item; refer to CoA/Spec Sheet.
• LogP, pKa, refractive index: Not specified for this item; refer to CoA/Spec Sheet.

Literature/general expectations for capped cysteine derivatives (guidance only)

• Physical state: Typically a white to off-white solid, hygroscopic tendencies possible for small peptide derivatives.
• Solubility profile: Frequently soluble in polar solvents (water, aqueous buffers, MeOH, EtOH) and DMSO; free thiol increases polarity. Salt formation is unnecessary since termini are neutralized by acylation/amide capping.
• Thiol acidity: Cysteine thiol pKa typically ~8–9 (literature, environment-dependent). Terminal capping has minor influence relative to local H-bonding and solvent.
• Stability: Free thiols readily oxidize to disulfides in air/alkaline media; solutions are best prepared fresh, oxygen-limited, and mildly acidic to neutral.

Practical implications

• Prepare solutions under inert gas where feasible and avoid prolonged exposure to basic pH to limit disulfide formation.
• If exact solubility or quantitative constants are required for your method validation, consult the item’s CoA/Spec Sheet.

Quality and Grades

Item-specific quality

• Grade/purity: Not specified for this item; refer to CoA/Spec Sheet.

Context for peptide/small amino acid derivative quality (general information)

• Typical peptide-chemistry specifications: Vendors commonly report HPLC area purity (e.g., ≥95%), identity by HRMS/ESI-MS, and occasionally 1H NMR and elemental analysis. For thiol-containing materials, additional testing for disulfide content or free thiol percentage may be provided.
• Stabilizers: None are typically added; the compound’s free thiol may slowly oxidize. Some lots may be packed under inert gas—check your CoA.
• UV profile: Small cysteine derivatives have weak chromophores; HPLC monitoring often at 210–220 nm. Low UV background is beneficial if the compound is used as a spacer/control in chromatographic assays.

Best practices

• Upon receipt, note lot-specific purity and identity data on the CoA. If your application is redox-sensitive, assess free thiol content by Ellman’s assay or LC-MS before critical experiments.
• If stringent impurity control is required (e.g., for quantitative kinetics), consider a quick polish by preparative HPLC under reducing conditions, then verify by analytical HPLC/MS.

Reaction and Applications

Use profile (general chemistry of this motif)

• Selective thiol chemistry: The free cysteine thiol allows highly chemoselective conjugation under mild conditions.
  • Michael addition to maleimides at pH ~6.5–7.5 (fast, selective).
  • S-alkylation with haloacetamides/iodoacetamides or activated sulfonates at pH ~7.5–8.3.
  • Disulfide formation by controlled oxidation (air, DMSO, iodine) and exchange reactions in buffered media.
  • Thioether formation via thiol–ene/thiol–yne click under radical initiation or photoredox conditions.
• Blocking groups and protection: If transient masking is needed, reversible S-protection (e.g., Acm, Trt) can be introduced and later removed; not present on this item unless stated on CoA.

Application concepts

• Fragment/linker design: Ac-Cys-NHMe is a minimal, neutralized cysteine mimic useful as a thiol handle without charged termini; helpful in probing thiol-selective reagents and in assembling thioether-linked adducts with defined end-capping.
• Controls and standards: Useful as a small-molecule model to optimize thiol-reactive labeling conditions before deploying on peptides/proteins.
• Surface/conjugate chemistry: Anchors to maleimide- or iodoacetamide-activated resins, nanoparticles, or dyes, generating stable S–C linkages.

Practical tips (literature/general)

• Keep oxygen and metals low to preserve the free thiol; verify state by Ellman’s reagent or LC-MS.
• For kinetic work, buffer capacity near neutral pH and ionic strength control improve reproducibility.

Reaction Conditions

General, literature-based guidance for thiol reactions with cysteine derivatives (adapt to your system)

• Maleimide conjugation

  • Solvent: Aqueous buffer (phosphate/HEPES), optional 10–20% organic cosolvent.
  • pH: 6.5–7.5 (selective for thiols over amines; avoids maleimide hydrolysis).
  • Temperature/time: RT, minutes to 1–2 h.
  • Notes: Include 0.5–1 mM EDTA to reduce metal-catalyzed side reactions; exclude oxygen as feasible.

• S-alkylation (iodoacetamide/haloacetate)

  • Solvent: Water or water/MeCN, DMF, or DMSO blends.
  • pH: 7.5–8.3 to deprotonate the thiol while minimizing base-promoted side reactions.
  • Temperature/time: RT, 0.5–4 h depending on electrophile.
  • Notes: Control equivalents to avoid overalkylation at other nucleophiles if present.

• Disulfide formation

  • Oxidants: Air/O2 (slow), DMSO (mild), ferricyanide or iodine (faster; quench excess).
  • Solvent: Aqueous buffer near neutral pH.
  • Temperature/time: RT, minutes to hours.
  • Notes: For symmetric disulfides, use equimolar partners; for mixed disulfides, employ preformed activated disulfides.

Verification

• Monitor progress by LC-MS or HPLC (210–220 nm). Confirm free thiol content by Ellman’s assay before conjugation.

Safety and Handling

Item-specific hazard data

• GHS classification: Not specified for this item; refer to SDS.
• Signal word / Pictograms / H-statements: Not specified for this item; refer to SDS.

General safety guidance for small thiol-containing peptide derivatives (literature/standard practice)

• PPE: Wear lab coat, nitrile gloves, and safety glasses. Use in a fume hood when weighing/dissolving powders to minimize inhalation of dust/aerosols.
• Incompatibilities: Avoid oxidizing agents (thiol → disulfide). Copper and other transition metals can catalyze oxidation; minimize contact with metal surfaces and metal salts. Peroxides in solvents can also promote oxidation.
• Handling: Work quickly with chilled, deoxygenated solvents for sensitive applications. Where compatible, add a small amount of benign reductant to working buffers (e.g., TCEP) to maintain the free thiol state; verify compatibility with your downstream chemistry.
• First aid (overview; see SDS): If inhaled, move to fresh air. On skin contact, wash with soap and water. Eye exposure: rinse cautiously with water for several minutes and seek medical attention if irritation persists. If ingested, rinse mouth and seek medical advice.
• Waste: Collect aqueous and organic waste according to institutional procedures for organic sulfur compounds/peptide derivatives.

Always consult the product’s SDS for authoritative safety information before use.

Solvent Selection

Applicability: As a polar, small peptide derivative with a free thiol and capped termini, Ac-Cys-NHMe is generally handled in polar protic solvents or water-miscible organics.

General solvent guidance (literature/general)

• Water/buffers: Often readily soluble. For maximum thiol stability, use degassed, metal-free buffers at pH 6.5–7.5.
• DMSO: Excellent solvating power; convenient for stock solutions followed by aqueous dilution. Degas and store aliquots to limit oxidation.
• Alcohols (MeOH, EtOH) and acetonitrile: Useful for preparative/analytical chromatography and for intermediate dissolutions.
• Avoid: Strongly basic media for prolonged periods (promotes oxidation/decomposition) and nonpolar solvents (limited solubility).

Selection tips

• For bioconjugation: Use aqueous buffer (e.g., phosphate, HEPES) with chelators (e.g., EDTA) to suppress metal-catalyzed oxidation; include compatible reductant if necessary.
• For S-alkylation/S-acylation: Polar aprotic solvents (DMF, DMSO, MeCN) or mixed aqueous–organic systems help dissolve electrophiles and maintain reactivity.

Mini comparison (general)

• Water vs DMSO: Water is greener and ideal for biological compatibility; DMSO enables higher concentration stocks and solubilization of hydrophobic partners. Blends are common.

Storage and Reconstitution

Item-specific conditions

• Storage: Store at -20°C (per product data). Keep container tightly closed.
• Shipping: Shipped in an ice chest with ice pads (per product data).

General handling recommendations for thiol-containing peptide derivatives

• Protect from air and moisture; consider storing under inert gas with desiccant.
• Light sensitivity is typically low, but protecting from strong light helps minimize inadvertent oxidation during handling.
• Aliquot upon first opening to minimize freeze–thaw and headspace oxygen exposure.

Reconstitution (guidance)

• Solvents: Water, aqueous buffers, or DMSO are commonly suitable for small cysteine derivatives; exact solubility is not specified for this item—refer to CoA/Spec Sheet or perform a small-scale solubility check.
• Concentration: Prepare concentrated stocks (e.g., 10–100 mM) in DMSO if long-term frozen storage is desired; flush with inert gas and freeze at -20°C or below.
• Stability of solutions: Freshly prepare working solutions; for multi-day use, store at 2–8°C under inert atmosphere with metal chelators and, if compatible, a mild reducing agent to maintain the free thiol.

Research use only: Not for human or veterinary use.

Structure and Identity

Overview: Ac-Cys-NHMe is an N- and C-terminally capped cysteine residue: the α-amino group is acetylated (Ac–) and the carboxylate is converted to a methylamide (–CONHMe). The side chain retains the cysteine thiol (–CH2–SH).

Item-specific identifiers

• CAS: 10061-65-1
• Molecular formula: Not specified for this item; refer to CoA/Spec Sheet.
• Molecular weight: Not specified for this item; refer to CoA/Spec Sheet.
• SMILES: Not specified for this item; refer to CoA/Spec Sheet.
• InChIKey: Not specified for this item; refer to CoA/Spec Sheet.

Structural features (general description)

• Core scaffold: α-amino acid backbone (cysteine) with both termini blocked (Ac- at N-terminus; –CONHMe at C-terminus).
• Functional groups: one thiol (sulfhydryl), two amide linkages (an N-acetyl amide and a methylamide). No free α-amino or carboxyl groups.
• Stereochemistry: Typically derived from L-cysteine in practice; absolute configuration for this catalog item is not specified.
• 2D description in words: Acetyl carbonyl linked to the backbone nitrogen; side chain –CH2–SH on the β-carbon; C-terminus converted to –C(=O)–NH–CH3.

Notes

• With the N-terminus acetylated, this molecule cannot serve as an N-terminal nucleophile in ligations (e.g., NCL). The unprotected thiol remains available for selective conjugation or oxidation.

Synthetic Utility

Functional handles and strategic value (general)

• S-center: Free thiol enables diverse S-functionalizations under mild, selective conditions. Key transformations include S-alkylation (haloacetamides, sulfonates), S-acylation (activated esters/anhydrides), and radical additions (thiol–ene/yne).
• End-caps: N-acetyl and C-methylamide termini remove competing reactivity at the α-amino and carboxyl groups, yielding a neutral building block ideal for modeling or as a pendant thiol unit in modular syntheses.
• Disulfide chemistry: Controlled oxidation furnishes symmetric or mixed disulfides, enabling reversible linkages or protecting strategies.

Use cases

• Preparation of thioether-linked conjugates and probes by coupling the thiol to maleimide-activated dyes, affinity tags, or polymer backbones.
• Assembly of small-molecule mimetics where a cysteine-like thiol is required without peptide charge; the methylamide modulates H-bonding and lipophilicity compared to free amides.
• As a calibration/benchmark substrate in method development for thiol quantitation, kinetics, or LC-MS workflows.

Notes

• For SPPS, protected amino acid derivatives (e.g., Fmoc-Cys(Trt)-OH) are typically used; Ac-Cys-NHMe functions more as a terminally capped model compound or thiol handle rather than an SPPS monomer.

Target Specificity

Not applicable. This product is a small molecule (cysteine derivative), not a biological targeting reagent or antibody. It does not have defined antigen/epitope specificity. Any selectivity arises from thiol chemoselectivity toward thiol-reactive electrophiles (see Reaction & Applications).

Häufig gestellte Fragen

How should this product be stored?

Store at ?20 °C. Freezer storage is required to maintain the specified shelf life.

How is this product shipped?

This product ships in an insulated container with ice pads. 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 10061-65-1, the molecular formula is C6H12N2O2S, and the molecular weight is 176.24 g/mol.

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.