How alpha-Crystallin Prevents the Aggregation of Insulin

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N. L. Vekshin

Institute of Cell Biophysics, Russian Academy of Sciences, 142290 Pushchino, Moscow Region, Russia; E-mail: nvekshin@rambler.ru

Received May 10, 2007; Revision received August 7, 2007

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Using steady-state, polarized, and phase-modulation fluorometry, the dithiothreitol-induced denaturation of insulin and formation of its complex with alpha-crystallin in solution were studied. Prevention of the aggregation of insulin by alpha-crystallin is due to formation of chaperone complexes, i.e. interaction of chains of the denatured insulin with alpha-crystallin. The conformational changes in alpha-crystallin that occur during complex formation are rather small. It is unlikely that N-termini are directly involved in the complex formation. The 8-anilino-1-naphthalenesulfonate (ANS) is not sensitive to the complex formation. ANS emits mainly from alpha-crystallin monomers, dimers, and tetramers, but not from oligomers or aggregates. The possibility of highly sensitive detection of aggregates by light scattering using a spectrofluorometer with crossed monochromators is demonstrated.

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KEY WORDS: alpha-crystallin, insulin, chaperone complex, aggregation, light scattering, fluorescence

DOI: 10.1134/S0006297908040111

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