Infrared Spectroscopic Studies of Protein Formulations Containing Glycine

Jeffrey D. Meyer, Shu Jun Bai, Meena Rani, Raj Suryanarayanan, Rajiv Nayar, John F. Carpenter, Mark C. Manning

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Glycine is extensively used as an excipient in protein formulations. However, it absorbs significant infrared (IR) radiation in the conformationally sensitive amide I region (1700-1600 cm-1) of proteins. Furthermore, glycine can form a number of polymorphs, as well as an amorphous phase. Each of these forms possibly exhibits a different IR absorption spectrum. Accurate subtraction of glycine signals, in order to obtain reliable amide I spectra, was found to be possible only if the protein-to-glycine ratio was ≥1:1. In those cases, the solid-state conformation of the protein could be determined. In addition, a new method for estimating the degree of crystallinity of freeze-dried glycine is described, using IR bands in the 1350-1300 cm -1 region.

Original languageEnglish (US)
Pages (from-to)1359-1366
Number of pages8
JournalJournal of Pharmaceutical Sciences
Issue number5
StatePublished - May 2004


  • Crystallinity
  • Glycine
  • Infrared spectroscopy
  • Lyophilization
  • Protein formulation
  • X-ray diffraction

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    Meyer, J. D., Bai, S. J., Rani, M., Suryanarayanan, R., Nayar, R., Carpenter, J. F., & Manning, M. C. (2004). Infrared Spectroscopic Studies of Protein Formulations Containing Glycine. Journal of Pharmaceutical Sciences, 93(5), 1359-1366.