Cell Penetrating Peptides

Commonly Used CPPs Most prospective therapeutic and diagnostic agents have very poor cell permeability and low bioavailability. Cell penetrating peptides (CPPs), also known as protein transduction domains have the ability to translocate through the cell membranes. As such, they have received formidable attention in the current advances in drug delivery as promising tools to overcome drug delivery problems. These peptides have been used to deliver drugs, imaging agents, and other therapeutic biomolecules across the cell membrane into the cytoplasm. Although the mechanism of their intracellular translocation is not clear, the amino acid composition which gives them a net positive charge seems to play a key role in this process.1 Di erent studies have hypothesized that internalization occurs via endocytosis, direct transport through the cell membrane or both. The primary structure of CPPs is generally composed of cationic residues such as arginines and lysines. Several naturally occurring and synthetic CPPs have been investigated in delivery of various cargo such as nucleic acids, proteins, quantum dots, contrast agents and small organic molecules.2 In all of these studies, CPPs exhibited minimal toxicity in biological systems, suggesting their potential as drug delivery vehicles. The table below highlights some of the most common naturally occurring and synthetic cell penetrating peptides. In this issue, we will be discussing the various CPPs and their advances in therapeutic applications. The HIV-1 TAT48-60 peptides is derived from an 86-amino acid TAT protein involved in replication of HIV-1. Studies have shown that the helical domain of TAT protein contains clusters of basic amino acids and plays a crucial role in translocation of TAT peptides into the cells.1 This domain contains multiple arginines which plays a vital role in the intracellular translocation capability of TAT peptides. When one arginine residue is deleted, TAT peptides cell permeability is decreased by half.2 HIV-1 TAT peptides have been used to deliver a variety biological molecules including large proteins such as RNase A, β-galactosidase among other proteins.4,5 Other biomolecules that have successfully been transported into the cells by linking them to TAT peptides include; liposomes,6 nanoparticles,4 peptide nucleic acids, DNA, siRNA7 and small molecules.

Most prospective therapeutic and diagnostic agents have very poor cell permeability and low bioavailability. Cell penetrating peptides (CPPs), also known as protein transduction domains have the ability to translocate through the cell membranes. As such, they have received formidable attention in the current advances in drug delivery as promising tools to overcome drug delivery problems. These peptides have been used to deliver drugs, imaging agents, and other therapeutic biomolecules across the cell membrane into the cytoplasm.
Although the mechanism of their intracellular translocation is not clear, the amino acid composition which gives them a net positive charge seems to play a key role in this process. 1 Di erent studies have hypothesized that internalization occurs via endocytosis, direct transport through the cell membrane or both. The primary structure of CPPs is generally composed of cationic residues such as arginines and lysines. Several naturally occurring and synthetic CPPs have been investigated in delivery of various cargo such as nucleic acids, proteins, quantum dots, contrast agents and small organic molecules. 2 In all of these studies, CPPs exhibited minimal toxicity in biological systems, suggesting their potential as drug delivery vehicles. The table below highlights some of the most common naturally occurring and synthetic cell penetrating peptides. In this issue, we will be discussing the various CPPs and their advances in therapeutic applications. Bio-Synthesis, a leading global manufacturer of high quality custom peptides and oligonucleotides. Our experts have enabled us to provide clients with the ability to design and manufacture advanced glycosylated and carbohydrate modi ed peptides for biopharmaceutical, diagnostic, and research applications. We continue to maintain integrity and professionalism as we serve our clients in areas spanning from proteomics to cell biology.
Bio-Synthesis has developed a reputation for both small and large scale synthesis using optimal processes that meet your speci cations. Being a US based company, all of our products are exclusively manufactured at our state-of-the-art facilities in Lewisville, Texas.

Polyarginines
Transportan Peptide Sequence Oligoarginines of 6-20 residues have been studied extensively for their ability to penetrate into cytoplasm through the cell membrane. It was found that optimal cell membrane permeation is achieved by oligoarginines residues between 5 and 15. 1 In particular, nona-arginine peptides were shown to have improved cell penetration e ciency compared to TAT peptides. 2 Thus, most studies have utilized octa-and nona-arginine peptides as delivery medium for most biological molecules including siRNA, anticancer drugs, small molecules, proteins, peptides, and oligonucleotides. 2,3 Since oligoarginine peptides are the most commonly used CPPs, their optimization to reduce cell toxicity and improve protease stability has been investigated. Replacement of L-arginines with D-amino acids resulted to protease resistant polyarginines with better intracellular translocation compared to the L-oligoarginines peptides. 4 In addition, fatty acids have been incorporated to generate more active peptides with low toxicity. Lee et. al. incorporated C14 fatty acid chains. The resulting lipooligoarginines peptides had increased cell permeation, improved metabolic stability and minimal cytotoxicity. 5 Oligoarginine peptides with minimal cell adsorption and uptake have also been designed by incorporating a polyglutamic chain as a counter ion domain. The protease labile linker between the polyglutamic and polyarginine domains releases the polyarginine domain for intracellular translocation. 6 It has been potrayed that the guanidino functional group plays a critical role in the intracellular translocation of oligoarginines peptides. Hence, several other guanidine containing molecules have been discovered. Wender et al., designed a polyguanidine peptoid derivative with improved cellular uptake compared to the TAT peptides and nonaarginine peptides containing D-amino acids. 4 This derivatization enhanced protease stability while maintaining cell permeation capability.
Transportan is a 21-mer nonarginine chimera of N-terminal neuropeptide galanin and venom peptide mastoparan. 1 Transportan has been used to deliver peptides, proteins, peptide nucleic acids and small molecules into various cell lines. 2 Several transportan analogs such as transportan 10, TP10, have been investigated. In TP10, the six N-terminal amino acid residues have been truncated, yet this peptide retains the cell translocating capabilities of the original peptide due to its amphiphatic features. 3