Unfolding of lysozyme by breaking its disulphide bridges results in exposure of hydrophobic sites.
The interaction of 1-anilino-naphthalene-8-sulphonate (ANS), a probe whose fluorescence is strongly dependent on hydrophobicity of the environment, with native lysozyme and lysozyme partially unfolded by breaking the disulphide bridges and reacting the free -SH groups with iodoacetamide, has been investigated. Monitoring the intensity of ANS fluorescence and the position of the emission maximum in the presence of native and partially unfolded lysozyme indicated that unfolding resulted in the exposure of hydrophobic sites. Hydrophobic sites could not be detected when native and partially unfolded lysozyme were denatured with urea or guanidinium chloride. Protein components of the cells export machinery like 'chaperones' associate only with partially unfolded proteins and not native, folded proteins. Hence, hydrophobic regions of proteins, exposed on partial unfolding, could be the sites of recognition by 'chaperone' proteins.
Joseph
M
M
Centre for Cellular and Molecular Biology, Hyderabad, India.
Nagaraj
R
R
D000817:Anilino Naphthalenesulfonates; D000818:Animals; D001665:Binding Sites; D002645:Chickens; D004220:Disulfides / Q000737:chemistry; D005456:Fluorescent Dyes; D006863:Hydrogen-Ion Concentration; D007460:Iodoacetamide; D015394:Molecular Structure; D009113:Muramidase / Q000737:chemistry*; D011489:Protein Denaturation; D013050:Spectrometry, Fluorescence
D000817:Anilino Naphthalenesulfonates; D004220:Disulfides; D005456:Fluorescent Dyes; C027132:1-anilino-8-naphthalenesulfonate; D009113:Muramidase; D007460:Iodoacetamide