Alpha-to-beta structural transformation of ovalbumin: heat and pH effects.
Ovalbumin is an important member of the serpin superfamily without inhibitory activity. The heat- and pH-induced alpha-to-beta structural transformations of ovalbumin were investigated by means of circular dichroism and binding of ANS and Congo red dyes. The native ovalbumin shows a mixture of alpha-helix and beta-sheet, while both the heat and alkali treatments are able to transform the native protein into a predominance of beta-sheet secondary structure. The free energy changes during transitions to the unfolded state are 5.19 kcal/mol from the native state and 4.00 kcal/mol from the heat-treated one. The binding abilities of the heat-treated and the alkali-treated forms to ANS and Congo red suggest that the altered forms exhibit hydrophobic exposure and intermolecular interaction. The results substantiate that the altered protein forms bearing increased beta-sheet structures are prone to aggregation, which is implicated in the pathogenesis of some conformational diseases.
Hu
H Y
HY
Shanghai Institute of Biochemistry, Chinese Academy of Sciences. hyhu@sunm.shcnc.ac.cn
Du
H N
HN
D000818:Animals; D002942:Circular Dichroism; D004396:Coloring Agents / Q000737:chemistry / Q000378:metabolism; D003224:Congo Red / Q000737:chemistry / Q000378:metabolism; D005456:Fluorescent Dyes / Q000737:chemistry / Q000378:metabolism; D019791:Guanidine / Q000737:chemistry; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D010047:Ovalbumin / Q000737:chemistry* / Q000378:metabolism*; D017510:Protein Folding; D020033:Protein Isoforms / Q000378:metabolism; D017433:Protein Structure, Secondary; D013050:Spectrometry, Fluorescence; D013816:Thermodynamics
D004396:Coloring Agents; D005456:Fluorescent Dyes; D020033:Protein Isoforms; D003224:Congo Red; D010047:Ovalbumin; D019791:Guanidine