The field of peptide science is constantly evolving, driven by the quest for more potent, specific, and functional peptide-based therapeutics and research tools. At the heart of these advancements lies the availability of specialized amino acid derivatives that allow for precise modifications and enhanced capabilities. Fmoc-4-Nitro-L-Phenylalanine, commonly denoted as Fmoc-Phe(4-NO2)-OH, is one such critical component that empowers peptide chemists to push the boundaries of innovation.

As a derivative of phenylalanine, Fmoc-4-Nitro-L-Phenylalanine (CAS No.: 95753-55-2) offers a unique modification: the incorporation of a nitro group at the para position of the phenyl ring, protected by the Fmoc (9-fluorenylmethyloxycarbonyl) group. This specific structure, with a Molecular Formula of C24H20N2O6 and a Molecular Weight of 432.43 g/mol, presents distinct chemical properties. Typically appearing as a white to off-white powder with high purity (≥98%), it is a reliable reagent for demanding peptide synthesis applications. Its stability is best maintained when stored at 2-8°C.

The strategic placement of the nitro group makes Fmoc-4-Nitro-L-Phenylalanine exceptionally useful in several advanced peptide design strategies. Firstly, it can be incorporated into peptide sequences to act as an intrinsic IR probe. This allows researchers to study the conformational dynamics of peptides, providing insights into folding mechanisms and interactions with target molecules. Secondly, the nitro group's electronic properties make it suitable for use as a quencher in FRET (Förster Resonance Energy Transfer) systems. This is invaluable for monitoring molecular proximity and conformational changes, crucial for understanding enzyme activity or receptor binding events.

Beyond these spectroscopic applications, Fmoc-4-Nitro-L-Phenylalanine serves as a vital intermediate in the synthesis of pharmacologically active compounds. Its most prominent use is in the creation of squaric acid derivatives that act as VLA-4 integrin antagonists. Targeting VLA-4 integrins is a significant therapeutic strategy for diseases characterized by excessive cell adhesion and inflammation, such as multiple sclerosis and inflammatory bowel disease. By enabling the construction of these precise molecular structures, this compound plays a direct role in the development of new treatments. It also serves as a building block for analogs of kahalalide F, further demonstrating its versatility in complex organic synthesis.

The availability of high-quality amino acid derivatives like Fmoc-4-Nitro-L-Phenylalanine from reliable chemical suppliers, such as NINGBO INNO PHARMCHEM CO.,LTD., is fundamental for researchers in academic and industrial settings. It empowers the design of innovative peptides that can serve as novel diagnostics, therapeutics, or research probes. The ongoing advancements in utilizing such specialized building blocks are key to unlocking the full potential of peptide science.