Conformational specificity of mini-alphaA-crystallin as a molecular chaperone.
The chaperone activity and biophysical properties of the 19 amino acid peptide DFVIFLDVKHFSPEDLTVK, identified as the functional element in alphaA-crystallin and here referred to as mini-alphaA-crystallin, were studied using light scattering and spectroscopic methods after altering its sequence and enantiomerism. The all-D and all-L conformers of the peptide do not show marked differences in their chaperone-like activity against heat-induced aggregation of alcohol dehydrogenase at 48 degrees C and dithiothreitol-induced aggregation of insulin. The retro peptide does not show any secondary structure and is also unable to act like a chaperone. Both all-L and all-D peptides lose their beta-sheet conformations, hydrophobicity and chaperone-like activity at temperatures > 50 degrees C. However, upon cooling, a significant portion of those properties was regained, suggesting temperature-dependent, reversible structural alterations in the peptides under investigation. We propose that both the hydrophobicity and beta-sheet conformation of the functional element of alphaA-crystallin are essential for chaperone-like activity.
Bhattacharyya
J
J
Mason Eye Institute, Departments of Ophthalmology and Biochemistry, University of Missouri, Columbia 65212, USA.
Sharma
K K
KK
D000595:Amino Acid Sequence; D002942:Circular Dichroism; D003459:Crystallins / Q000737:chemistry*; D018832:Molecular Chaperones / Q000737:chemistry*; D008969:Molecular Sequence Data; D017433:Protein Structure, Secondary; D013056:Spectrophotometry, Ultraviolet
D003459:Crystallins; D018832:Molecular Chaperones