Search Result

Results for "

cysteine residue

" in MedChemExpress (MCE) Product Catalog:

By Targets:	ADC Cytotoxin (1) ADC Linker (4) Amino Acid Derivatives (2) Antibiotic (1) Apoptosis (4) Autophagy (2) Bacterial (2) Biochemical Assay Reagents (13) Cathepsin (3) CRM1 (1) Deubiquitinase (2) DNA Methyltransferase (1) DNA/RNA Synthesis (2) Drug Metabolite (1) EGFR (3) Endogenous Metabolite (1) Farnesyl Transferase (1) Fluorescent Dye (7) Fungal (1) GLP Receptor (1) Glutaminase (1) Hippo (MST) (1) Histone Methyltransferase (3) HIV (1) HPV (1) IKK (1) Influenza Virus (2) MARCKS (1) Mps1 (1) NF-κB (3) NO Synthase (1) Parasite (2) PDHK (1) Phosphatase (1) PKC (1) Ras (1) RGS Protein (1) RNA MTase (1) SARS-CoV (2) STING (2) TRP Channel (1) Virus Protease (1) β-glucuronidase (1)
By Research Areas:	Cancer (21) Infection (7) Inflammation/Immunology (10) Metabolic Disease (4) Neurological Disease (4)

By Targets:

ADC Cytotoxin (1)

ADC Linker (4)

Amino Acid Derivatives (2)

Antibiotic (1)

Apoptosis (4)

Autophagy (2)

Bacterial (2)

Biochemical Assay Reagents (13)

Cathepsin (3)

CRM1 (1)

Deubiquitinase (2)

DNA Methyltransferase (1)

DNA/RNA Synthesis (2)

Drug Metabolite (1)

EGFR (3)

Endogenous Metabolite (1)

Farnesyl Transferase (1)

Fluorescent Dye (7)

Fungal (1)

GLP Receptor (1)

Glutaminase (1)

Hippo (MST) (1)

Histone Methyltransferase (3)

HIV (1)

HPV (1)

IKK (1)

Influenza Virus (2)

MARCKS (1)

Mps1 (1)

NF-κB (3)

NO Synthase (1)

Parasite (2)

PDHK (1)

Phosphatase (1)

PKC (1)

Ras (1)

RGS Protein (1)

RNA MTase (1)

SARS-CoV (2)

STING (2)

TRP Channel (1)

Virus Protease (1)

β-glucuronidase (1)

By Research Areas:

Cancer (21)

Infection (7)

Inflammation/Immunology (10)

Metabolic Disease (4)

Neurological Disease (4)

Inhibitors & Agonists

Screening Libraries

Fluorescent Dye

Peptides

Natural
Products

Targets Recommended: ASCT

Cat. No.	Product Name	Target	Research Areas	Chemical Structure

HY-D2381

AF 488 maleimide	Fluorescent Dye	Others
AF 488 maleimide is a thiol-reactive dye for labeling of protein SH groups, and it can be used to attach AF 488 fluorophore to proteins and peptides containing cysteine residues, as well as to other thiolated molecules. AF488 exhibits the λ_em and λ_ex wavelength of 520 nm and 470 nm, respectively .

HY-D0843

N-Ethylmaleimide 15+ Cited Publications NEM	Cathepsin Deubiquitinase Apoptosis	Others
N-Ethylmaleimide (NEM) derives from maleic acid, it can alkylates free sulfhydryl. N-Ethylmaleimide is an irreversible cysteine protease inhibitor. N-ethylmaleimide specific inhibits phosphate transport in mitochondria. N-Ethylmaleimide inhibits prolyl endopeptidase with an IC₅₀ value of 6.3 μM. N-Ethylmaleimide can be used to modify cysteine residues in proteins and peptides .

HY-135113

Lanthionine	Amino Acid Derivatives	Others
Lanthionine is a cysteine derivative. Lanthionine is linked by a disulfide bond formed by an oxidation reaction between two cysteine residues .

HY-P4101

Cys(Npys)-TAT (47-57)	HIV	Infection
Cys(Npys)-TAT (47-57) is a peptide fragment of TAT peptide and it is able to interact with plasmid DNA electrostatically. Cys(Npys)-TAT (47-57) is corresponding to the transduction domain of TAT with an activated cysteine residue C. TAT is a small nuclear transcriptional activator protein encoded by HIV-1 .

HY-N11085

Isophysalin A	NO Synthase IKK	Inflammation/Immunology
Isophysalin A is a physalin with alpha and beta unsaturated ketone components. Isophysalin A binds to GSH and targets multiple cysteine residues on IKKβ. Isophysalin A also inhibits inducible NO synthase (iNOS) and nitric oxide (NO) production, showing anti-inflammatory activity .

HY-P10533

Cysteine peptide	Biochemical Assay Reagents	Others
Cysteine peptide is a heptapeptide containing a cysteine residue whose thiol group makes it susceptible to a range of oxidative modifications. Cysteine peptide is used to detect the skin sensitization potential of chemicals including cosmetic ingredients .

HY-137251

Sulfo-MBS sodium	Biochemical Assay Reagents	Others
Sulfo-MBS sodium is a heterobifunctional crosslinker with a maleimide group and an N-hydroxysuccinimide (NHS) ester group, which can react with cysteine residues and lysine residues on proteins. Sulfo-MBS sodium be used for protein cross-linking studies .

HY-171029

C902	Amino Acid Derivatives	Others
C902 is a cysteine residue in the RAG1 protein, that binds to Zn ²⁺ ion and contributes to the DNA cleavage .

HY-N5182

Chymostatin B	Others	Others
Chymostatin B is a subtype of chymostatin characterized by a valine residue. Chymostatin inhibits chymotrypsin, papain, and other *serine/cysteine* endopeptidases** .

HY-N5180

Chymostatin A	Others	Others
Chymostatin A is a subtype of chymostatin characterized by a leucine residue. Chymostatin inhibits chymotrypsin, papain, and other *serine/cysteine* endopeptidases** .

HY-N5183

Chymostatin C	Others	Others
Chymostatin C is a subtype of chymostatin characterized by a leucine residue. Chymostatin inhibits chymotrypsin, papain, and other *serine/cysteine* endopeptidases** .

HY-120128

MTSEA hydrobromide	Biochemical Assay Reagents	Neurological Disease
MTSEA hydrobromide is a sulfhydryl-reactive compound that modifies free cysteine residues to produce a positively charged side chain approximately the size of lysine .

HY-19730A

Olmutinib hydrochloride HM61713 hydrochloride; BI 1482694 hydrochloride	EGFR	Cancer
Olmutinib hydrochloride is an orally active and irreversible third EGFR tyrosine kinase inhibitor that binds to a cysteine residue near the kinase domain. Olmutinib hydrochloride is used for NSCLC .

HY-145674

HDP 30.1699	DNA/RNA Synthesis ADC Cytotoxin	Cancer
HDP 30.1699, the derivative of α-Amanitin, shows considerable cross-links. The cysteine residues of the anti-HER2 THIOMAB antibody are used for conjugation of the cysteine reactive linker–Amanitin compound, HDP 30.1699, with a cleavable linker by maleimide chemistry .

HY-P10871

cTEV6-2	Virus Protease	Infection
cTEV6-2 binds to the cysteine residue (C151) of tobacco etch virus protease (TEV protease), and covalently inhibits TEV protease with an IC₅₀ of 81.7 nM .

HY-19730

Olmutinib 5+ Cited Publications HM61713; BI 1482694	EGFR	Cancer
Olmutinib (HM61713; BI-1482694) is an orally active and irreversible third EGFR tyrosine kinase inhibitor that binds to a cysteine residue near the kinase domain. Olmutinib is used for NSCLC .

HY-12809

Optovin 1 Publications Verification	TRP Channel	Neurological Disease
Optovin is a reversible photoactivated TRPA1 ligand that enables light-mediated neuronal excitation. Optovin activates TRPA1 via structure-dependent photochemical reactions with redox-sensitive cysteine residues .

HY-14645

(-)-DHMEQ 25+ Cited Publications Dehydroxymethylepoxyquinomicin	NF-κB	Inflammation/Immunology Cancer
(-)-DHMEQ (Dehydroxymethylepoxyquinomicin) is a potent, selective and irreversible NF-κB inhibitor that covalently binds to a cysteine residue. (-)-DHMEQ inhibits nuclear translocation of NF-κB and shows anti-inflammatory and anticancer activity .

HY-N12776

Illudalic acid	Phosphatase	Cancer
Illudalic acid is a potent and selective Leukocyte antigen-related (LAR) phosphatase inhibitor with an IC₅₀ value of 1.30 µM. Illudalic acid inhibits LAR phosphatase through covalent ligation to the catalytic cysteine residue .

HY-129654

MTSES sodium Sodium (2-Sulfonatoethyl)methanethiosulfonate	Biochemical Assay Reagents	Others
MTSES sodium (Sodium (2-Sulfonatoethyl)methanethiosulfonate) is a negatively charged, membrane-impermeable methanethiosulfonate (MTS). MTS is a compound that reacts with sulfhydryl groups to form mixed disulfide bonds and is often used to study cysteine ??residues on proteins.

HY-112906

C-176 Maximum Cited Publications 71 Publications Verification	STING	Inflammation/Immunology
C-176 is a selective and blood-brain barrier permeable STING inhibitor. C-176 covalently targets transmembrane cysteine residue 91 and thereby blocking activation-induced palmitoylation of STING .

HY-W800720

S-(Pyridin-2-ylthio)-L-homocysteine	Biochemical Assay Reagents	Others
(S)-2-amino-4-(2-(pyridin-2-yl)disulfanyl)butanoic acid is a small molecule reagent with a 2-thiopyridine linked to a short amino acid. SPDP is a thiol-specific labeling reagent, commonly used in reversibly binding cysteine residues on proteins. The disulfide bond it forms with the cysteine is selectively cleaved in the reducing environment of the cell cytoplasm.

HY-D0843R

N-Ethylmaleimide (Standard)	Cathepsin Deubiquitinase Apoptosis	Others
Bayogenin (Standard) is the analytical standard of Bayogenin. This product is intended for research and analytical applications. Bayogenin is an alfalfa saponin, shows moderate potency of glycogen phosphorylase inhibition .

HY-162156

TTK inhibitor 4	Mps1	Cancer
TTK inhibitor 4 (compound 16) is a potent inhibitor of threonine tyrosine kinase (TTK), with the IC₅₀ value of 0.016 μM, that has anti-tumor activity .

HY-W615327

Bis-sulfone NHS ester	Biochemical Assay Reagents	Others
Bis-sulfone NHS Ester is a bis-alkylating labeling reagent that is selective for the cysteine sulfur atoms from a native disulfide. These reagents undergo bis-alkylation to conjugate both thiols derived from the two cysteine residues of a reduced native disulfide bond such as the interchain disulfide bonds of an antibody. The reaction results in covalent rebridging of the disulfide bond via a three carbon bridge leaving the protein structurally intact.

HY-138683

STING-IN-3 2 Publications Verification	STING	Inflammation/Immunology
STING-IN-3 is an inhibitor of stimulator of interferon genes (STING). STING-IN-3 efficiently inhibits both hsSTING and mmSTING through covalently target the predicted transmembrane cysteine residue 91 and thereby block the activation-induced palmitoylation of STING .

HY-P5681

Human α-Defensin 6	Bacterial	Infection Inflammation/Immunology
Human α-Defensin 6, a 32-residue cysteine-rich peptide, can inhibit bacterial invasion and contribute to the mucosal immunity. Human α-Defensin 6 forms ordered self-assembly fibrils and nanonets that surround and entangle bacteria after stochastic binding to bacterial surface proteins. Human α-Defensin 6 also inhibits C. albicans biofilm formation .

HY-116254

L-739750	Farnesyl Transferase	Others
L-739750 is a selective protein farnesyltransferase (PFTase) inhibitor (IC₅₀: 0.4 nM). PFTase utilizes farnesyl diphosphate to farnesylate the cysteine residue of protein substrates having a C-terminal CAAX motif. L-739750 is a selective CAAX peptidomimetic .

HY-16909

Leptomycin B 5+ Cited Publications CI 940; LMB	CRM1 Fungal Antibiotic	Infection Cancer
Leptomycin B (CI 940; LMB) is a potent inhibitor of the nuclear export of proteins. Leptomycin B inactivates CRM1/exportin 1 by covalent modification at a cysteine residue. Leptomycin B is a potent antifungal antibiotic blocking the eukaryotic cell cycle .

HY-128945

CL2A	ADC Linker	Inflammation/Immunology Cancer
CL2A is a claevable complicated PEG8- and triazole-containing PABC-peptide-mc linker. CL2A is cleavable through pH sensitivity, giving rise to bystander effect, and binds the antibody at a cysteine residue via a disulfide bond. Labetuzumab govitecan used this linker .

HY-W878827

Bis-sulfone-PEG12-NHS ester	Biochemical Assay Reagents	Others
Bis-sulfone-PEG12-NHS Ester is a bis-alkylating labeling reagent that is selective for the cysteine sulfur atoms from a native disulfide. These reagents undergo bis-alkylation to conjugate both thiols derived from the two cysteine residues of a reduced native disulfide bond such as the interchain disulfide bonds of an antibody. The reaction results in covalent rebridging of the disulfide bond via a three carbon bridge leaving the protein structurally intact. The hydrophilic PEG spacer increases solubility in aqueous media.

HY-W190952

Bis-sulfone-PEG4-NHS ester	Biochemical Assay Reagents	Others
Bis-sulfone-PEG4-NHS Ester is a bis-alkylating labeling reagent that is selective for the cysteine sulfur atoms from a native disulfide. These reagents undergo bis-alkylation to conjugate both thiols derived from the two cysteine residues of a reduced native disulfide bond such as the interchain disulfide bonds of an antibody. The reaction results in covalent rebridging of the disulfide bond via a three carbon bridge leaving the protein structurally intact. The hydrophilic PEG spacer increases solubility in aqueous media.

HY-W800627

Bis-sulfone-PEG8-NHS ester	Biochemical Assay Reagents	Others
Bis-sulfone-PEG8-NHS Ester is a bis-alkylating labeling reagent that is selective for the cysteine sulfur atoms from a native disulfide. These reagents undergo bis-alkylation to conjugate both thiols derived from the two cysteine residues of a reduced native disulfide bond such as the interchain disulfide bonds of an antibody. The reaction results in covalent rebridging of the disulfide bond via a three carbon bridge leaving the protein structurally intact. The hydrophilic PEG spacer increases solubility in aqueous media.

HY-135056

MitoTracker Green FM 5+ Cited Publications	Fluorescent Dye	Others
Mito-Tracker Green is a green fluorescent dye that selectively accumulates in the mitochondrial matrix. MitoTracker Green FM covalently binds mitochondrial proteins by reacting with free mercaptan of cysteine residues, allowing staining of mitochondrial membrane potential independent of membrane potential. Excitation/emission wavelength 490/523 nm.

HY-137028

2′-Thioadenosine PD157432	EGFR	Cancer
2'-Thioadenosine (PD157432) is a selective and irreversible inhibitor of ErbB-1 and ErbB-2, with an IC₅₀ of 45 µM for ErbB-2. 2'-Thioadenosine covalently inactivates ErbB-1 via modification of a cysteine residue at the active site .

HY-123749

Tetramethylrhodamine-5-iodoacetamide 5-TMRIA	Fluorescent Dye	Others
Tetramethylrhodamine-5-iodoacetamide (5-TMRIA) is a thiol-selective reactive dye that is used to non-specifically label proteins via the cysteine residues. Tetramethylrhodamine-5-iodoacetamide (5-TMRIA) can be used to covalently label DNA fragments .

HY-W017464

NAPQI N-Acetyl-4-benzoquinone Imine	Drug Metabolite Endogenous Metabolite	Metabolic Disease
NAPQI is the toxic metabolite of Acetaminophen (HY-66005). NAPQI is also an inhibitor of enzymes in the vitamin K cycle. NAPQI is rapidly detoxified by glutathione (GSH), but in situations of GSH deficiency, excess NAPQI reacts with cysteine residues in proteins, causing cell death and toxicity in the liver .

HY-128945A

CL2A TFA	ADC Linker	Inflammation/Immunology Cancer
CL2A TFA is a claevable complicated PEG8- and triazole-containing PABC-peptide-mc linker. CL2A TFA is cleavable through pH sensitivity, giving rise to bystander effect, and binds the antibody at a cysteine residue via a disulfide bond. Labetuzumab govitecan used this linker .

HY-N0191

Andrographolide 20+ Cited Publications Andrographis	NF-κB SARS-CoV Influenza Virus Autophagy Parasite	Infection Inflammation/Immunology Cancer
Andrographolide is a NF-κB inhibitor, which inhibits NF-κB activation through covalent modification of a cysteine residue on p50 in endothelial cells without affecting IκBα degradation or p50/p65 nuclear translocation. Andrographolide has antiviral effects.

HY-W578278

tert-Butyl (2-(pyridin-2-yldisulfanyl)ethyl)carbamate	Biochemical Assay Reagents	Others
tert-Butyl (2-(pyridin-2-yldisulfanyl)ethyl)carbamate consists of a tert-butyl group, where the protected amine can be deprotected under mild acidic conditions, and the other part of the molecule may act as a thiol-specific labeling reagent, commonly used in reversibly binding cysteine residues on proteins.

HY-130149

Adagrasib 35+ Cited Publications MRTX849	Ras	Cancer
Adagrasib (MRTX849) is a potent, orally-available, and mutation-selective covalent inhibitor of KRAS G12C with potential antineoplastic activity. Adagrasib covalently binds to KRAS G12C at the cysteine at residue 12, locks the protein in its inactive GDP-bound conformation, and inhibits KRAS-dependent signal transduction .

HY-19564

JX06 2 Publications Verification	PDHK Apoptosis	Cancer
JX06 is a potent, selective and covalent inhibitor of PDK. JX06 inhibits PDK1, PDK2 and PDK3 with IC₅₀s of 49 nM, 101 nM, and 313 nM, respectively. JX06 inhibits PDK1 activity via covalently binding to a cysteine residue in an irreversible manner. JX06 shows significant antitumor activity .

HY-D1783

MitoTracker Deep Red FM 4 Publications Verification	Fluorescent Dye	Others
MitoTracker Deep Red FM fluorescent dye that selectively accumulates in the mitochondrial matrix. MitoTracker Deep Red FM covalently binds mitochondrial proteins by reacting with free mercaptan of cysteine residues, allowing staining of mitochondrial membrane potential independent of membrane potential. Excitation/emission wavelength 644/665 nm . Storage: Keep away from light.

HY-N0191R

Andrographolide (Standard)	NF-κB SARS-CoV Influenza Virus Autophagy Parasite	Infection Inflammation/Immunology Cancer
Andrographolide (Standard) is the analytical standard of Andrographolide. This product is intended for research and analytical applications. Andrographolide is a NF-κB inhibitor, which inhibits NF-κB activation through covalent modification of a cysteine residue on p50 in endothelial cells without affecting IκBα degradation or p50/p65 nuclear translocation. Andrographolide has antiviral effects.

HY-172721

Cy3B maleimide	Fluorescent Dye	Others
Cy3B maleimide is a mono-reactive dye containing maleimide group, which can selectively and efficiently attach Cyanine3 fluorophore (an analog of Cy3) to proteins and peptides containing cysteine residues, as well as to other thiolated molecules (such as thiol-containing oligonucleotides). Cy3B is an improved version of Cy3 dyes with significantly increased fluorescence quantum yield and photostability.

HY-116255

MS453	Histone Methyltransferase	Others
MS453 is a potent and highly selective SETD8 inhibitor with an IC50 value of 804 nM. MS453 specifically modifies a cysteine residue close to the inhibitor binding site. MS453 is selective for 28 other methyltransferases. The crystal structure of MS453 reveals its binding mode to SETD8, providing an atomic-level view for the development of high-quality chemical probes for SETD8 .

HY-152919

Mal-amide-PEG8-Val-Cit-PAB-OH	ADC Linker	Cancer
Mal-amide-PEG8-Val-Cit-PAB-OH is a cleavable ADC linker featuring a maleimide, a hydrophilic PEG spacer, a Val-Cit dipeptide, and a PAB functional group. Maleimide is used to covalently bind free thiols on the cysteine residues of proteins. The Val-Cit dipeptide is cleaved by cellular proteases within the cell to allow for efficient payload delivery with the help of the PAB structure.

HY-D1363

BDP R6G maleimide	Fluorescent Dye	Others
BDP R6G maleimide is a borodipyrromethane fluorophore with absorption and emission wavelengths similar to those of R6G rhodamine. Sulfhydryl labelling is a common protein modification where the cysteine residues in the protein allow more site-specific labelling than the NHS ester of the amine group. BDP R6G maleimide is a thiol reactive dye that reacts with thiol groups to form thioester bonds .

HY-158378

Trivalent hydroxyarsinothricn R-AST-OH	Glutaminase	Cancer
Trivalent hydroxyarsinothricn (R-AST-OH) is a covalent and irreversible kidney-type glutaminase (KGA) inhibitor. Trivalent hydroxyarsinothricn binds to the glutamine binding site and forms a covalent bond with an active site cysteine residue. Trivalent hydroxyarsinothricn selectively kills triple-negative breast cancer (TNBC) cells and is not cytotoxic to the control cell line. KGA is the enzyme that controls glutamine metabolism and is correlated with tumor malignancy .

HY-172291

Mal-amide-PEG8-Val-Cit-PAB-PNP	ADC Linker	Cancer
Mal-amide-PEG8-Val-Cit-PAB-PNP is a cleavable ADC linker featuring a maleimide, a PEG spacer, a Val-Cit dipeptide, a PAB. and a PNP carbonate. Maleimide is a thiol-specific covalent linker which is used to label cysteine residues in proteins while the PNP group acts as a highly activated leaving group. Val-Cit linkers are cleaved by cytoplasmic peptidases.

Cat. No.	Product Name

HY-L153

Cysteine Targeted Covalent Library

4,813 compounds

Covalent inhibitors are small molecules that can bind specifically to target proteins through covalent bonds and inhibit their biological functions. Although for a long time, covalent targeting has been playing a subordinate role in drug discovery, with an increasing number of reports on successful clinical applications of such drugs, the potential of these agents is now being acknowledged. Currently, cysteine is the most common covalent amino acid residue in a variety of covalent drugs, and various warheads have been developed that can react with cysteine, providing the key building blocks for covalent drugs to form covalent bonds.

To meet the development needs of covalent inhibitors targeting cysteine, MCE has designed a unique collection of 4,813 compounds with different covalent warheads that target cysteine. The MCE Cysteine Targeted Covalent Library is designed using the following covalent warheads: Acrylamides, Propiolic acid ester, Dimethylamine functionalized acrylamides, Chloroacetamides, Acrylonitrile, 2-Cyanoacrylamide, Aziridine, Haloacetamide, etc.

HY-L154

Cysteine Targeted Covalent Fragment Library

3,371 compounds

To meet the development needs of covalent inhibitors targeting cysteine, MCE has designed a unique collection of 3,371 fragments with different covalent warheads that target cysteine. The MCE Cysteine Targeted Covalent Fragment Library is designed using the following covalent warheads: Acrylamides, Propiolic acid ester, Dimethylamine functionalized acrylamides, Chloroacetamides, Acrylonitrile, 2-Cyanoacrylamide, Aziridine, Haloacetamide, etc. All fragments are pre-filtered with the Rule of Three restrictions which can be used for fragment-based covalent drug development.

HY-L915

Lysine Focused Covalent Fragment Library

437 compounds

Lysine is the second most common target residue used in the design of TCIs and related covalent ligands. Its appeal lies in its abundance in human proteins, which is approximately three times higher than that of cysteine (5.8% vs. 1.9%). This significantly increases the number of proteins suitable for covalent targeting, especially given that many human proteins lack ligandable cysteine residues. Moreover, it has been suggested that functional lysines have a lower probability of being replaced by mutation, as they often play a crucial role in catalysis by acting as bases or nucleophiles. Additionally, lysines are essential for maintaining the structural integrity of proteins and for regulating post-translational modifications (PTMs). Consequently, targeting lysine has garnered significant interest in recent years.

Through careful selection, we constructed a structural filter containing over 110 electrophilic groups. By analyzing the electrophilic fragments selected by the structural filter, we removed any molecules with trivial or undesirable structural features. Ultimately, we obtained 445 fragment molecules which can target lysine residue and can be used for fragment-based covalent drug discovery.

HY-L908

Lead-like Covalent Screening Library

1,273 compounds

Small molecule covalent inhibitors, or irreversible inhibitors, are a type of inhibitors that exert their biological functions by irreversibly binding to target through covalent bonds. Compared with non-covalent inhibitors, covalent inhibitors have obvious advantages in bioactivity, such that covalent warheads can target rare residues of a particular target protein, thus leading to the development of highly selective inhibitors and achieving a more complete and continued target occupancy in living systems. In recent years, the distinct strengths of covalent inhibitors in overcoming drug resistance had been recognized. However, toxicity can be a real challenge related to this class of therapeutics due to their potential for off-target reactivity and has led to these drugs being disfavored as a drug class. The drug design and optimization of covalent inhibitors has become a hot spot in drug discovery.

MCE Lead-like Covalent Screening Library offers a valuable resource of 1,049 lead-like compounds with commonly used covalent warheads. These warheads, such as acrylamide, activated terminal alkyne, acyloxymethyl ketone, and boronic acid, are capable of reacting with specific amino acid residues, including cysteine, lysine, serine, and histidine. The inclusion of these reactive warheads in the library allows researchers to explore the potential of covalent inhibition, a powerful approach in drug discovery.

HY-L913

Tyrosine Focused Covalent Fragment Library

120 compounds

Recently, significant advancements in tyrosine-targeting electrophiles have primarily occurred in the field of protein-protein interactions (PPIs), where cysteine residues are often underrepresented and novel chemistries are needed to address these interfaces. In this context, tyrosines are frequently more accessible compared to more buried binding sites. Moreover, they are commonly found at "hot spots," which are functional epitopes of PPIs, with 12.3% of the residues consisting of tyrosines. This prevalence is likely due to the hydrophobic nature of tyrosine, its ability to participate in aromatic π-interactions, and its capacity for hydrogen bonding. Beyond PPIs, some progress has also been made in covalent tyrosine targeting in other areas where more commonly addressed side chains are lacking. Even though tyrosine has a slightly lower pKa value compared to the protonated lysine side chain (approximately 10 vs. 10.5 for the unprotected amino acid side chains), significantly less progress has been made in the development of tyrosine-targeted covalent ligands compared to lysine. This is likely due to the reduced flexibility of the tyrosine side chain and the greater steric hindrance of its hydroxy group, which makes it more challenging to adopt suitable reaction geometries.

Through careful selection, we constructed a structural filter containing over 110 electrophilic groups. By analyzing the electrophilic fragments selected by the structural filter, we removed any molecules with trivial or undesirable structural features. Ultimately, we obtained 124 fragment molecules which can target tyrosine residue and can be used for fragment-based covalent drug discovery.

Cat. No.	Product Name	Type

HY-D2381

AF 488 maleimide	Fluorescent Dyes/Probes
AF 488 maleimide is a thiol-reactive dye for labeling of protein SH groups, and it can be used to attach AF 488 fluorophore to proteins and peptides containing cysteine residues, as well as to other thiolated molecules. AF488 exhibits the λ_em and λ_ex wavelength of 520 nm and 470 nm, respectively .

HY-135056

MitoTracker Green FM 5+ Cited Publications	Fluorescent Dyes/Probes
Mito-Tracker Green is a green fluorescent dye that selectively accumulates in the mitochondrial matrix. MitoTracker Green FM covalently binds mitochondrial proteins by reacting with free mercaptan of cysteine residues, allowing staining of mitochondrial membrane potential independent of membrane potential. Excitation/emission wavelength 490/523 nm.

HY-123749

Tetramethylrhodamine-5-iodoacetamide 5-TMRIA	Dyes
Tetramethylrhodamine-5-iodoacetamide (5-TMRIA) is a thiol-selective reactive dye that is used to non-specifically label proteins via the cysteine residues. Tetramethylrhodamine-5-iodoacetamide (5-TMRIA) can be used to covalently label DNA fragments .

HY-D0098

Fluorescein-5-maleimide

3 Publications Verification

N-(5-Fluoresceinyl)maleimide

Fluorescent Dyes/Probes

Fluorescein-5-maleimide (N-(5-Fluoresceinyl)maleimide) is a fluorescent dye. Fluorescein-5-maleimide can be used to detect the redox state of thiols in eukaryotic cells. Fluorescein-5-maleimide can label peptides and is used to detect negatively charged nanoparticles. Fluorescein-5-maleimide can also label actin to explore its interaction with cardiac myosin-binding protein C (cMyBP-C), which helps in developing small molecule modulators for heart failure. Fluorescein-5-maleimide can screen mutant proteins that contain cysteine residues. The excitation wavelength of Fluorescein-5-maleimide is 494 nm, and the emission wavelength is 519 nm .

HY-172721

Cy3B maleimide

Fluorescent Dyes/Probes

Cy3B maleimide is a mono-reactive dye containing maleimide group, which can selectively and efficiently attach Cyanine3 fluorophore (an analog of Cy3) to proteins and peptides containing cysteine residues, as well as to other thiolated molecules (such as thiol-containing oligonucleotides). Cy3B is an improved version of Cy3 dyes with significantly increased fluorescence quantum yield and photostability.

HY-D1363

BDP R6G maleimide

Fluorescent Dyes/Probes

BDP R6G maleimide is a borodipyrromethane fluorophore with absorption and emission wavelengths similar to those of R6G rhodamine. Sulfhydryl labelling is a common protein modification where the cysteine residues in the protein allow more site-specific labelling than the NHS ester of the amine group. BDP R6G maleimide is a thiol reactive dye that reacts with thiol groups to form thioester bonds .

Cat. No.	Product Name	Target	Research Area

HY-135113

Lanthionine	Amino Acid Derivatives	Others
Lanthionine is a cysteine derivative. Lanthionine is linked by a disulfide bond formed by an oxidation reaction between two cysteine residues .

HY-P4101

Cys(Npys)-TAT (47-57)	HIV	Infection
Cys(Npys)-TAT (47-57) is a peptide fragment of TAT peptide and it is able to interact with plasmid DNA electrostatically. Cys(Npys)-TAT (47-57) is corresponding to the transduction domain of TAT with an activated cysteine residue C. TAT is a small nuclear transcriptional activator protein encoded by HIV-1 .

HY-P10533

Cysteine peptide	Biochemical Assay Reagents	Others
Cysteine peptide is a heptapeptide containing a cysteine residue whose thiol group makes it susceptible to a range of oxidative modifications. Cysteine peptide is used to detect the skin sensitization potential of chemicals including cosmetic ingredients .

HY-P10871

cTEV6-2	Virus Protease	Infection
cTEV6-2 binds to the cysteine residue (C151) of tobacco etch virus protease (TEV protease), and covalently inhibits TEV protease with an IC₅₀ of 81.7 nM .

HY-P4087

Cys(Npys)-(Arg)9	Peptides	Others
Cys(Npys)-(Arg)9 is a cell penetrating peptide. Cys(Npys)-(Arg)9 is comprised of 9 D-Arginine residues and an activated cysteine residue C(Npys). Cys(Npys)-(Arg)9 can be used as a carrier peptide applicable in conjugation and cell permable studies .

HY-P5681

Human α-Defensin 6	Bacterial	Infection Inflammation/Immunology
Human α-Defensin 6, a 32-residue cysteine-rich peptide, can inhibit bacterial invasion and contribute to the mucosal immunity. Human α-Defensin 6 forms ordered self-assembly fibrils and nanonets that surround and entangle bacteria after stochastic binding to bacterial surface proteins. Human α-Defensin 6 also inhibits C. albicans biofilm formation .

HY-P10428

E6AP-mimicking peptide	HPV	Infection
E6AP-mimicking peptide (compound 13) is a high-affinity, selective, irreversible and potent peptide-based covalent HPV16 E6 inhibitor targeting the 16E6 oncoprotein using a cysteine-reactive acrylamide warhead. E6AP-mimicking peptide has a K_i of 17 nM. E6AP-mimicking peptide targets all residues appearing in the binding pocket of E6 to disrupt the binding interface of 16E6 and E6AP. E6AP-mimicking peptide selectively binds and crosslinks to MBP-16E6 in PBS or a protein mixture .

HY-P5439

Epsilon-V1-2, Cys-conjugated	PKC MARCKS	Others
Epsilon-V1-2, Cys-conjugated is a biological active peptide. (This peptide is the εPKC specific inhibitor. Its inhibitory activity is based on εPKC translocation and MARCKS phosphorylation. This peptide interferes with εPKC interaction with the anchoring protein εRACK. This peptide contains a cysteine residue added to the C-terminus for potential S-S bond formation with a carrier protein.Pyroglutamyl (pGlu) peptides may spontaneously form when either Glutamine (Q) or Glutamic acid (E) is located at the sequence N-terminus. The conversion of Q or E to pGlu is a natural occurrence and in general it is believed that the hydrophobic γ-lactam ring of pGlu may play a role in peptide stability against gastrointestinal proteases. Pyroglutamyl peptides are therefore considered a normal subset of such peptides and are included as part of the peptide purity during HPLC analysis.)

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cysteine residue

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