Interaction of alpha-lactalbumin with mini-alphaA-crystallin |
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Authors: | Sreelakshmi Y Sharma K K |
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Institution: | (1) Departments of Ophthalmology and Biochemistry, University of Missouri, Columbia, Missouri, 65212 |
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Abstract: | A-Crystallin can function like a molecular chaperone. We have recently shown that residues 71-88 in A-crystallin represent the chaperone active site of the protein. A peptide containing the sequence of A-crystallin sequence DFVIFLDVKHFSPEDLTVK (mini A-crystallin) by itself displays the antiaggregation property of A-crystallin. We have prepared a complex of reduced -lactalbumin and mini- A-crystallin and investigated the nature, conformation, and properties of the complex by dynamic light scattering, HPLC analysis, CD spectroscopy, and fluorescence studies. Although mini- A was able to prevent the precipitation of reduced -lactalbumin, large aggregates (50-500 nm) of the complex were formed during the assay. Amino acid composition estimation revealed that -lactalbumin and mini- A-crystallin were present in 1:2 ratio in the aggregates. During our study significant red shift in the Trp fluorescence emission maximum and an increase in Bis-ANS binding to the mini A-crystallin-bound -lacatalbumin were observed. The CD spectra of the complex showed a significant loss of -helical content but the -sheet content appeared to be less affected, indicating the molten-globule state of the reduced lactalbumin in the complex. These data show that the active site of A-crystallin by itself can maintain a significantly denatured and unfolded protein in soluble form. |
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Keywords: | Alpha lactalbumin chaperone-like aggregation light scattering crystallin small heat shock protein |
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