Vibrational circular dichroism studies of epidermal growth factor and basic fibroblast growth factor.
Vibrational circular dichroism (VCD) studies are reported for two unrelated recombinant growth factor proteins: epidermal growth factor and basic fibroblast growth factor (bFGF). NMR, electronic CD, and bFGF X-ray studies indicate that these two proteins are primarily composed of beta-sheet and loop secondary structure elements with no detectable alpha-helices. Two reports on solution conformation of these proteins using FTIR absorption spectroscopy with subsequent resolution enhancement confirmed the presence of a large fraction of a beta-sheet conformation but in addition indicated the presence of large absorption bands in the 1650-1656 cm-1 region, which are typically assigned to alpha-helices. The VCD spectra of both proteins have band shapes that strongly resemble those of other high beta-sheet fraction proteins, such as the trypsin family of proteins. Quantitative analysis of the VCD spectra also indicates that these proteins are predominantly in beta-sheet and extended ("other") conformations with very little alpha-helix fraction. These results agree with the CD interpretation and affirm that the FTIR peaks in the region 1650-1656 cm-1 can be assigned to loops. This study provides an example of the limitations of using FTIR frequencies alone for examination of protein secondary structure.
Dukor
R K
RK
Department of Chemistry, University of Illinois, Chicago 60680.
Pancoska
P
P
Keiderling
T A
TA
Prestrelski
S J
SJ
Arakawa
T
T
D002942:Circular Dichroism; D004815:Epidermal Growth Factor / Q000737:chemistry*; D016222:Fibroblast Growth Factor 2 / Q000737:chemistry*; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000737:chemistry; D013055:Spectrophotometry, Infrared; D014732:Vibration
D011994:Recombinant Proteins; D016222:Fibroblast Growth Factor 2; D004815:Epidermal Growth Factor