A partially folded state of ovalbumin at low pH tends to aggregate.
At pH 2, ovalbumin retains native-like secondary structure as seen by far-UV CD and FTIR, but lacks well-defined tertiary structure as seen by the fluorescence and near-UV CD spectra. Addition of 20 mM Trifluoroacetic acid (TFA) or 30 mM Trichloroacetic acid (TCA) on acid-induced state results in protein aggregation. This aggregated state possesses extensive β-sheet structure as revealed by far-UV CD and FTIR spectroscopy. Furthermore, the aggregates exhibit decreased ANS fluorescence and increased thioflavin T fluorescence. The presence of aggregates was confirmed by size exclusion chromatography. Such a formation of β-sheet structure is found in the amyloid of a number of neurological diseases such as Alzheimer's and scrapie. Ovalbumin at low pH, in the presence of K(2)SO(4), exists in partially folded state characterized by native-like secondary structure and tertiary folds.
Naeem
Aabgeena
A
Department of Biochemistry, Faculty of Life Science, AMU, Aligarh 202 002, India. aabgeenanaim@rediffmail.com
Khan
Taqi Ahmed
TA
Muzaffar
Mohammad
M
Ahmad
Saman
S
Saleemuddin
M
M
D000682:Amyloid / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D010047:Ovalbumin / Q000737:chemistry*; D017510:Protein Folding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary
D000682:Amyloid; D010047:Ovalbumin