How α-crystallin prevents the aggregation of insulin

Abstract

Using steady-state, polarized, and phase-modulation fluorometry, the dithiothreitol-induced denaturation of insulin and formation of its complex with α-crystallin in solution were studied. Prevention of the aggregation of insulin by α-crystallin is due to formation of chaperone complexes, i.e. interaction of chains of the denatured insulin with α-crystallin. The conformational changes in α-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 α-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.