User:Ammembalsadi

Introduction
Aptides represent a novel class of high-affinity peptides, first described by Kim et al. in 2012. These molecules exhibit remarkable specificity, binding to their target molecules with affinities in the nanomolar range. They offer several advantages over other widely-used targeting molecules, such as aptamers and antibodies. While antibodies have garnered significant attention for their specific binding and precise targeting capabilities, they also face challenges, including complex intellectual property issues and limited penetrability. Aptides address these challenges due to their smaller size, with a maximum length of approximately 30 amino acids. This diminutive size facilitates rapid extravasation in vivo. The name "aptides" is derived from the term 'aptamer-like' peptides. Sequence and Structure Aptides derive their structure from the Basic Leucine Zipper (bZIP) class of peptides. These bZIP peptides function as transcriptional regulators in eukaryotes, achieving high affinity, sequence-specific recognition. Mimicking these peptides, aptides possess a stabilizing scaffold comprised of 12 tryptophan repeats in a bZIP-like beta hairpin structure (with a melting temperature of 72°C). This structure is reinforced by two tryptophan–tryptophan cross-strand pairs. To enable aptides to recognize multiple target proteins, similar to the DNA recognition sites of bZIP proteins, two randomizable regions of six amino acids each have been introduced at each end of the trpzip using glycine linkers. Aptides are designed to bind their target proteins through the synergistic action of these two binding sites. Applications Compared to antibodies, peptides, including aptides, offer several advantages for specific biomedical applications. They can be chemically synthesized in large quantities (up to kilogram scales) at a fraction of the cost. Additionally, the risk of contamination by cellular materials is significantly reduced with peptides. Furthermore, peptides can be readily conjugated with cytotoxic drugs, facilitating drug delivery applications. [Citations needed]

Recent research has identified potential applications of aptides in the realm of medical imaging and targeted therapeutics. For instance, they have been used to detect Extra Domain B (EDB) in breast cancer-initiating cells and in Lewis lung carcinoma models. These findings suggest that aptides targeting EDB could be valuable for magnetic resonance imaging (MRI) of certain cancers. HyPEP Body: A Hybrid Therapeutic Approach A challenge facing peptide-based therapeutics is their short plasma half-life, which results from rapid proteolysis and renal clearance in vivo. To address this limitation, researchers have been exploring hybrid approaches that combine features of antibodies and peptides. Techniques such as "Peptibody" and "CovX-body" have been developed to enhance the plasma half-life of peptide therapeutics. However, these techniques have their own set of challenges, including limited tumor penetration and manufacturing hurdles.

To overcome these challenges, a new molecular platform named "HyPEP-body" has been introduced. This hybrid complex combines an anti-hapten antibody with a hapten-labeled bispecific peptide. The construct utilizes cotinine, a nicotine metabolite, as a hapten tag and an anti-cotinine antibody (Abcot) to form the HyPEP body. [Citations needed]