Conformation of glutathione adduct and oxidized forms of platelet-derived growth factor.
The conformational properties of several platelet-derived growth factors (PDGFs) were characterized by circular dichroism (CD), Fourier transform infrared spectroscopy (FTIR), gel filtration and sedimentation equilibrium. Three different forms of disulfide linked dimer, PDGF-AA, PDGF-AB, and PDGF-BB, showed similar far UV CD spectra with evidence for slight beta-structure, but little evidence of other regular secondary structures. These spectra were, however, different from the far UV CD spectra of the glutathione adducts of PDGF-A and B, suggesting that the latter two proteins adopt different conformations in the absence of intra- or inter-molecular disulfide bonds. FTIR studies confirmed this by showing that the glutathione adducts of the PDGF-B protein have a significantly lower amount of regular secondary structures than PDGF-BB. Additionally, the increased bandwidths of the amide I components of the FTIR spectrum of the glutathione adduct indicates a more flexible structure relative to the dimeric form. Sedimentation equilibrium analysis showed that PDGF-BB is primarily a dimer and that the glutathione form is primarily a monomer. Thus, it was concluded that the glutathione derivative has little affinity to form non-covalent dimers in neutral solution.
Narhi
L O
LO
Amgen Inc., Thousand Oaks, CA.
Kenney
W C
WC
Prestrelski
S J
SJ
Arakawa
T
T
Lyons
D
D
Lary
J
J
Yphantis
D A
DA
D002850:Chromatography, Gel; D002942:Circular Dichroism; D005978:Glutathione / Q000737:chemistry*; D010084:Oxidation-Reduction; D010982:Platelet-Derived Growth Factor / Q000737:chemistry*; D011487:Protein Conformation; D013056:Spectrophotometry, Ultraviolet; D014461:Ultracentrifugation
D010982:Platelet-Derived Growth Factor; D005978:Glutathione