Cys(Npys)-(D-Arg)9

Product Name: Cys(Npys)-(D-Arg)9

Sequence One Letter Code: C(Npys)RRRRRRRRR-NH2

Sequence Three Letter Code: H-Cys(Npys)-D-Arg-D-Arg-D-Arg-D-Arg-D-Arg-D-Arg-D-Arg-D-Arg-D-Arg-NH2

Chemical Formula:C62H118N40O12S2

Molecular Weight: 1679.9

Purity: 95%

Form: Lyophilized

Storage Conditions: - 20 °C

Research Area: Cell Penetrating Peptides

Source / Species: Synthetic construct

Conjugation: Unconjugated

Code Nacres: NA.26

Application: D-Arg9-Cys(Npys) Cell-Penetrating Peptide is a cell-penetrating peptide composed of nine D-arginine residues and a C-terminal cysteine protected with a 3-nitro-2-pyridinesulfenyl (Npys) group. The poly-D-arginine sequence confers strong membrane translocation and intracellular delivery capabilities, while the Npys-activated cysteine enables selective disulfide exchange with cysteine-containing peptides or proteins. This design allows efficient formation of unsymmetrical disulfide-linked conjugates for intracellular delivery of biomolecules. The peptide is widely used in bioconjugation strategies, intracellular transport studies, and delivery of functional proteins, including genome-editing enzymes and other therapeutic macromolecules.

Current Research: Efficient delivery of biomolecules into living cells remains a major challenge in biomedical research and therapeutic development. Many biologically active molecules—including peptides, proteins, and nucleic acids—cannot easily cross the plasma membrane due to their size or charge. Cell-penetrating peptides (CPPs) provide a powerful solution to this problem by facilitating transport of cargo molecules into cells. One widely used CPP is the polyarginine peptide, particularly sequences composed of multiple arginine residues. The D-Arg9-Cys(Npys) cell-penetrating peptide combines a poly-D-arginine translocation domain with a chemically reactive cysteine residue protected by a 3-nitro-2-pyridinesulfenyl (Npys) group. This design enables both efficient cellular uptake and controlled conjugation to target molecules, making it a valuable tool for intracellular delivery and bioconjugation strategies. Structure and Design of the Peptide The peptide consists of two functional components that work together to enable delivery and conjugation: Poly-D-arginine sequence (D-Arg9) The peptide contains nine arginine residues synthesized in the D-amino acid configuration. Polyarginine sequences are among the most effective cell-penetrating peptides known, and the positive charge of the guanidinium groups promotes interaction with negatively charged components of the cell membrane. Using D-amino acids instead of L-amino acids offers several advantages: Increased resistance to proteolytic degradation Enhanced stability in biological environments Prolonged intracellular activity C-terminal cysteine with Npys protection At the C-terminus, the peptide includes a cysteine residue protected with an Npys (3-nitro-2-pyridinesulfenyl) group. This functional group is specifically designed to enable controlled disulfide exchange reactions with other cysteine-containing molecules. Together, these elements make the peptide both an efficient intracellular delivery vehicle and a bioconjugation scaffold. Mechanism of Cellular Uptake Polyarginine peptides such as D-Arg9 are well known for their ability to cross cellular membranes. Their uptake involves interactions between the positively charged arginine side chains and negatively charged molecules on the cell surface, including glycosaminoglycans and phospholipids. These interactions promote internalization through mechanisms that may include: Endocytosis Direct membrane translocation Macropinocytosis Once internalized, the CPP can deliver attached cargo molecules into the cytoplasm or other intracellular compartments. Npys-Activated Cysteine for Controlled Conjugation The Npys protecting group attached to the cysteine residue plays a critical role in controlled conjugation chemistry. Npys allows selective disulfide bond formation through thiol–disulfide exchange reactions. When the peptide encounters another molecule containing a free cysteine thiol, the Npys group can undergo exchange, forming an unsymmetrical disulfide bond between the two molecules. This strategy offers several advantages: Site-specific conjugation to cysteine-containing biomolecules Formation of stable yet reversible disulfide linkages Compatibility with proteins, peptides, and other thiol-containing cargo Because disulfide bonds can be reduced in the intracellular environment, these linkages may also allow controlled release of cargo molecules inside cells. Applications in Intracellular Delivery The D-Arg9-Cys(Npys) peptide is widely used as a delivery platform for transporting biologically active molecules across cellular membranes. By forming disulfide-linked conjugates with cargo molecules, the peptide can facilitate entry into cells and deliver functional biomolecules to intracellular targets. Common cargo molecules include: Peptides and proteins Enzymes Antibodies or antibody fragments Nucleic acid–binding proteins Because of its efficient uptake and stable conjugation chemistry, the peptide is particularly useful in experimental systems requiring controlled intracellular delivery. Use in Genome Editing and Protein Delivery One important application of this CPP system is the delivery of genome-editing enzymes such as CRISPR-associated nucleases. Protein-based genome editing approaches often require efficient transport of large macromolecules into cells. By conjugating genome-editing proteins to the D-Arg9 CPP through cysteine-mediated disulfide bonds, researchers can enhance cellular uptake while maintaining enzymatic activity. This approach is also applicable to other functional proteins used in cell biology and therapeutic research. Applications in Bioconjugation and Chemical Biology Beyond delivery applications, the peptide is widely used in bioconjugation studies. The Npys-activated cysteine provides a convenient way to generate unsymmetrical disulfide-linked conjugates under controlled conditions. These conjugates can be used to study: Intracellular trafficking of proteins Peptide–protein interactions Targeted delivery systems Redox-sensitive biomolecular linkages Such strategies are particularly valuable in chemical biology, where controlled modification of biomolecules is essential for studying cellular processes. A Tool for Intracellular Transport and Biomolecule Engineering The D-Arg9-Cys(Npys) cell-penetrating peptide combines efficient membrane translocation with versatile conjugation chemistry. Its poly-D-arginine sequence enables strong cellular uptake, while the Npys-activated cysteine provides a site for controlled disulfide linkage to cysteine-containing biomolecules. Through applications in bioconjugation, intracellular transport studies, and delivery of functional proteins, this peptide continues to serve as a powerful tool in research involving protein engineering, therapeutic delivery strategies, and genome-editing technologies.