pH-dependent stability and conformation of the recombinant human prion protein PrP(90-231).
A recombinant protein corresponding to the human prion protein domain encompassing residues 90-231 (huPrP(90-231)) was expressed in Escherichia coli in a soluble form and purified to homogeneity. Spectroscopic data indicate that the conformational properties and the folding pathway of huPrP(90-231) are strongly pH-dependent. Acidic pH induces a dramatic increase in the exposure of hydrophobic patches on the surface of the protein. At pH between 7 and 5, the unfolding of hPrP(90-231) in guanidine hydrochloride occurs as a two-state transition. This contrasts with the unfolding curves at lower pH values, which indicate a three-state transition, with the presence of a stable protein folding intermediate. While the secondary structure of the native huPrP(90-231) is largely alpha-helical, the stable intermediate is rich in beta-sheet structure. These findings have important implications for understanding the initial events on the pathway toward the conversion of the normal into the pathological forms of prion protein.
Swietnicki
W
W
Department of Pathology, Case Western Reserve University, Cleveland, Ohio 44106, USA.
Petersen
R
R
Gambetti
P
P
Surewicz
W K
WK
D002942:Circular Dichroism; D006801:Humans; D006863:Hydrogen-Ion Concentration; D011328:Prions / Q000737:chemistry*; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000737:chemistry; D013056:Spectrophotometry, Ultraviolet; D013816:Thermodynamics
D011328:Prions; D011994:Recombinant Proteins