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