Both α-crystallin from bovine eye lens and Hsp16.3 from
Mycobacterium tuberculosis are members of the small heat shock protein
family. They were preincubated at 100°C for 15 min and then cooled
on ice immediately. The chaperone-like activities of preheated proteins
were measured at 37° using DTT-treated insulin B chains as
substrates. Both preheated proteins exhibited greatly enhanced
chaperone-like activities, accompanied with almost unchanged secondary
structures and surface hydrophobicity but with a minor change in
tertiary structures. The dramatically enhanced chaperone-like
activities of preheated a-crystallin and Hsp16.3 may have resulted from
the irreversible change in the tertiary structure as detected by
near-UV CD spectra
