Biopharmaceutical Form and Function

Most biopharmaceuticals are proteins or protein conjugates that are characterized by unique conformation in solution, which is essential for their function. Protein-conformation studies are valuable tools that help scientists understand the relationship between structure and function. These studies also help scientists evaluate biologicals’ comparability (e.g., in the event of process or formulation changes).The interest in conformational analysis is likely to increase in the near future as more companies develop biosimilars. The results of the analysis will help scientists compare generic biologicals with branded products. Approaches to the Conformational Analysis of Biopharmaceuticals surveys the technologies available for examining biopolymers.

Approaches to the Conformational Analysis of Biopharmaceuticals, Roger K. Lundblad, Ed., CRC Press, Boca Raton, FL, 2010, 347 pp., ISBN: 9781439807804

The book’s first two chapters introduce the topics of conformational analysis and the comparability of drug substances or formulations. Tables in Chapter Two summarize studies that evaluate the effect of chemical modifications, pressure, and temperature on protein conformation. They effectively encapsulate useful information about proteins, reagents, reaction conditions, results, and references and are quite useful for readers.Subsequent chapters offer excellent reviews of various instrumental techniques that reveal biomolecular conformation. These techniques include electrophoresis, affinity chromatography, size-exclusion chromatography, ultracentrifugation, differential scanning calorimetry, light scattering, luminescence, near- and mid-infrared spectroscopy, Raman and ultraviolet-visible spectroscopy, optical rotary dispersion, circular dichroism, nuclear magnetic resonance, chemical probes, and hydrogen exchange. Each chapter introduces one technique and enumerates its potential applications. Helpful tables list examples of applications and provide a wealth of references that can serve as good starting points for novices.

Next, the book discusses chemical modifications of biopolymers. In this process, a chemical reagent is reacted with a protein’s functional groups. The author provides a long list of examples of chemical modifications with references. The chapter also explains the mechanism of action of various compounds.Scientists sometimes use immunological reactivity as a measure of biopolymers’ conformational integrity, and one of the book’s chapters describes this technique. It is essential to ensure that biosimilar products are nonimmunogenic. Likewise, products that have been reformulated or manufactured by modified processes must also be nonimmunogenic. This chapter’s discussion of using the enzyme-linked immunosorbent assay, a technique applied extensively to diagnostic products, to evaluate biopharmaceuticals’ immunological reactivity is particularly informative.

Other chapters explain how techniques such as limited proteolysis, crystallographic analysis, small-angle neutron and X-ray scattering, equilibrium dialysis, and enzyme kinetics can analyze proteins’ conformations. These techniques are not universally applicable. The chapter highlights the fact that they apply to certain cases and provides examples.

Finally, readers gain practical advice about developing an experimental approach for conformational analysis in the last chapter. The author gives practical tips about the need for documentation and about using multiple analytical approaches. A table compares various technological approaches, shows the amount of samples each requires, and indicates each approach’s limitations. The choice of assay is critical and should enable regulatory compliance.Overall, this book is an excellent reference for scientists who must select appropriate methods for conformational analysis. The text provides relatively brief notes about each technique, but supplements them with useful references and presents its explanations in language that is easy to understand. The book provides useful guidance for performing the conformational analysis of biopharmaceuticals, an application which will only become more important as follow-on biologics gain prominence.

Sanjay Garg is deputy head of the School of Pharmacy at the University of Auckland, New Zealand, and a member of Pharmaceutical Technology's Editorial Advisory Board, s.garg@auckland.ac.nz.