Amino acid composition of cell-penetrating peptides (CPPs)

Cell-penetrating peptides (CPPs) such as the HIV TAT peptides are able to enter cells by direct translocation and endocytosis. Click here to see details about the CPP: http://lifetein.com/Cell_Penetrating_Peptides.html

About Cell-Penetrating Peptides

cell penetrating peptide entry mechanism

Cell Penetrating Peptides

The following table shows a selection of currently known CPPs, their origins, and sequences.
Name

Origin

Sequence

Tat (48-60)

HIV-1 protein

GRKKRRQRRRPPQQ

     plsl

Igl-1 homeodomain

RVIRVWFQNKRCKDKK

STR-R8

Stearly-RRRRRRRR-amide (Stearyl = CH3(CH2)16CO-)

STR-(RxR)4

Stearly-(RxR)4-amide (X=6-aminohexanoic acid)

Peptide Synthesis for Cell-penetration Studies

Cell-penetrating peptides (CPPs) have the ability to enter a cell’s plasma membrane independent of a membrane receptor. Attached to a CPP, therapeutic cargo could be delivered to an intracellular target, thus overcoming the entry restrictions set by the plasma membrane.

Peptide Synthesis & Cell Penetration

The cationic CPPs interact with negatively charged head groups of lipids directly in the plasma membrane through electrostatic interactions. The increased local peptide concentration at the membrane surface will cause a transient destabilization of the lipid bilayer and lead to cell entry. The hydrophobic interactions, especially facilitated by the presence of tryptophan residues, may be important for the CPP-membrane interaction and cellular internalization.

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Synthetic Peptide Vaccine Research: Problems and Accomplishments

 

Synthetic Peptide Vaccine Research: Problems and Accomplishments

Advancements in Peptide Vaccine Research: Tackling Pancreatic Cancer and Beyond

Insulin Peptide

The tragic loss of Apple’s co-founder, Steve Jobs, to pancreatic cancer in 2011 underscored the urgent need for effective cancer treatments. Pancreatic cancer, known for its lethality and as the fourth leading cause of cancer deaths globally, highlights the critical need for advancements in medical research, particularly in the realm of immunotherapy.

One promising avenue is the development of synthetic-peptide-based vaccines. These vaccines are engineered to stimulate T cell immunity, offering potential in both preventing and treating various diseases, including malignant disorders like cancer. Peptide vaccines have shown promise in generating antigen-specific responses in pancreatic cancer, targeting the unique differences between healthy and cancerous cells.

A notable target in cancer cells is Mucin 1 (MUC1), a glycoprotein that differs in structure between normal and cancerous cells. Peptide vaccines targeting MUC1 have demonstrated the ability to elicit an immune response, including the production of antibodies against its unique peptide sequences. Clinical trials are currently exploring the potential of MUC1 peptide vaccines in cancer immunotherapy.

Moreover, cancer cells exhibit distinct characteristics in terms of telomere-building enzymes and vascular endothelial growth factors (VEGF). For instance, the GV1001 peptide, a telomerase-based vaccine, has shown promising results in inducing an immune response in pancreatic cancer patients. Similarly, a VEGFR2–169 peptide vaccine, used alongside chemotherapy, has extended median survival in advanced pancreatic cancer patients, with further studies underway.

Tailoring peptide vaccines to individual patients is another emerging strategy. In a pilot study, patients with pancreatic and colorectal cancers received vaccines containing K-Ras peptides specific to their cancer mutations, leading to prolonged survival and significant T-cell responses in a subset of patients.

However, the journey in peptide vaccine research is not without challenges. The inherent low immunogenicity of peptides poses a hurdle, though various strategies, such as modifying key residues and combining peptides with more immunogenic substances, are being explored to enhance their effectiveness.

The future of peptide vaccines in cancer treatment requires a deep understanding of how cancers evade immune detection and how to counteract these mechanisms. Ongoing research aims to optimize peptide dosage, vaccine formulation, and identification of the most effective T cell epitopes, crucial for the success of future clinical trials.

In the realm of infectious diseases, the 2009 swine flu outbreak caused by the H1N1 virus strain brought to light the potential of peptide-based treatments. Researchers have identified a killer decapeptide (KP) with potent action against the influenza A virus. This peptide, derived from an anti-idiotypic antibody, has shown promising results in reducing viral levels and improving survival rates in animal models.

The versatility of synthetic peptides extends beyond cancer treatment to infectious disease control, with ongoing research in using peptides for HIV-2 detection and antibody production. The growing number of therapeutic peptides in clinical use and trials underscores their potential as a novel therapeutic strategy in various clinical settings. The question “Will killer peptide offer new therapy against swine flu H1N1 virus?” remains at the forefront of scientific inquiry, reflecting the ongoing efforts to harness peptide-based solutions in combating both infectious diseases and cancer.

The exploration of peptides in obesity control further illustrates their diverse therapeutic potential. Research has shown that certain peptide hormones, like glucagon and GLP-1, can be engineered to target multiple body mechanisms for weight normalization. High-potency glucagon-based co-agonist peptides, for instance, have demonstrated significant efficacy in reducing obesity and improving glucose tolerance in animal studies. This represents a promising direction in the quest for effective weight management therapies.

As the field of peptide research continues to evolve, it offers a beacon of hope in addressing some of the most pressing health challenges of our time, from cancer and infectious diseases to obesity. The versatility and specificity of peptides make them an attractive option in the therapeutic landscape, paving the way for more targeted and effective treatments across a broad spectrum of diseases.

References:

  • G. Conti, W. Magliani, S. Conti, L. Nencioni, R. Sgarbanti, A.T. Palamara, L. Polonelli. “Therapeutic activity of an anti-idiotypic antibody-derived killer peptide against influenza A virus experimental infection.” Antimicrobial Agents and Chemotherapy, 52. 12: 4331-4337
  • Day JW, etc. “A new glucagon and GLP-1 co-agonist eliminates obesity in rodents.” Nat Chem Biol. 2009 Oct;5(10):749-57. Epub 2009 Jul 13.

This comprehensive view of peptide vaccine research and therapeutic peptides underscores their significant role in advancing medical science and offers a glimpse into the future of healthcare.

Research on Synthetic Peptide Vaccines

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