title: Infrared spectroscopic studies of protein formulations containing glycine.
abstract: 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.
authors.affiliation: Center for Pharmaceutical Biotechnology, University of Colorado Health Sciences Center, Denver, Colorado, USA.
authors.forename: Jeffrey D
authors.initials: JD
authors.lastname: Meyer
authors.forename: Shu
authors.initials: S
authors.lastname: Jun Bai
authors.forename: Meena
authors.initials: M
authors.lastname: Rani
authors.forename: Raj
authors.initials: R
authors.lastname: Suryanarayanan
authors.forename: Rajiv
authors.initials: R
authors.lastname: Nayar
authors.forename: John F
authors.initials: JF
authors.lastname: Carpenter
authors.forename: Mark C
authors.initials: MC
authors.lastname: Manning
mesh_terms: D002626:Chemistry, Pharmaceutical; D005612:Freeze Drying / Q000379:methods; D005998:Glycine / Q000032:analysis*; D011506:Proteins / Q000032:analysis*; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods
chemical_list: D011506:Proteins; D005998:Glycine