In the world of biopharmaceuticals, large and complex protein therapeutics often dominate the landscape. As innovation accelerates, many of these therapeutics undergo chemical modifications to enhance their properties or improve drug delivery. However, not all amino acid–based drugs are large proteins; many peptides are increasingly being used in the treatment of various diseases.
Peptide medicines trace their origins to fundamental biochemical research that uncovered the diverse physiological roles of peptides. Today, peptides play a vital role in treating a range of disease conditions. Advances in chemistry have further expanded the production of synthetic and modified peptides.
However, synthetic peptides present unique challenges in structural characterization due to their non-biological origin. These analytical challenges require both conventional techniques (used for biologically derived peptides and proteins) and specialized approaches tailored for synthetic products. Recognizing this shift, regulatory bodies like the EMA and FDA have developed specific guidelines to address the complexities associated with synthetic peptide development and approval (1, 2).
Modern analytical technologies have revolutionized peptide research. Enhanced instrumentation not only supports the development, control and production of synthetic peptides but also deepens our understanding and investigation of naturally occurring peptides, a field now known as “peptidomics.” These advances pave the way for next-generation peptide therapeutics.
Discover how early analytical strategies enabled the structural characterization of human CGRP, a potent vasodilator. This foundational Nature paper offers valuable insights into peptide analysis techniques still relevant today.
Like all therapeutics, structural characterization is essential for peptide products. Regulatory agencies have adopted guidelines such as ICH Q6B, which outline general requirements for structural analysis. A primary requirement is the determination of the amino acid sequence and any modifications, which can be often achieved completely using mass spectrometry.
Mass spectrometry has become the primary analytical tool for peptide characterization, applicable to synthetic products and recombinant molecules.
The dominance of mass spectrometry in peptide research stems from its structural agnosticism and ability to provide both qualitative and quantitative data.
Despite their relatively small size, therapeutic peptides can adopt complex 3D conformations and investigating these higher order structures is important.
Aggregation must also be considered. Common methods include:
Orthogonal techniques for HOS investigations are recommended. Orthogonality using multiple, complementary techniques is emphasized in both regulatory guidances (1, 2) to ensure robust structural characterization.
As mentioned above, peptides can have their own unique analytical challenges. One such challenge is chirality. Most biological processes utilize L-forms of amino acids, but D-forms may be intentionally included to enhance stability or other attributes. Therefore, chirality must be investigated thoroughly.
D-amino acids, if present outside their intended sequence positions, are considered impurities. Mass spectrometry can help detect such impurities, even those that do not alter the mass, like D- vs. L-amino acids (Fig. 2) and Aspartic acid/Iso-aspartic acid isomers. These subtle changes, although "hiding in plain sight," can have significant impacts on peptide function and safety.
Other product-related impurities, such as oxidation and deamidation (as mentioned in the peptide mapping section above), also arise from chemical production processes and must be investigated. Regulatory expectations vary based on the relative abundance of these impurities. Relative abundance thresholds must be met, with analytical strategies tailored to meet both EMA and FDA expectations.
In addition to product-related impurities, process-related impurities must be addressed. These arise from the manufacturing process itself and include:
Regulatory guidance from the EMA and FDA outlines expectations for identifying and quantifying these impurities. The EMA guidelines, for example, explicitly mention nitrosamines, while the FDA guidance does not. Refer to ICH guidelines for assessing each impurity type.
Peptide characterization demands an analytical strategy capable of providing a detailed and accurate structural definition of the product. This is crucial for all peptide therapeutics, whether produced synthetically or recombinantly. The regulatory expectations are not only clear, but achievable using state-of-the-art instrumentation and scientifically sound methodologies. As the peptide landscape continues to evolve, thorough structural characterization will remain essential for ensuring safety, efficacy, and to meet regulatory expectations.
Whether you're navigating early-stage development or preparing for regulatory submission, BioPharmaSpec offers expert-driven peptide analysis services to help you meet structural characterization requirements with confidence.
Contact our scientists today to discuss your peptide project and receive a tailored analytical strategy.
