Complexes containingα-crystallin were isolated from crosslinked lens extract using an affinity column constructed with monoclonal antibodies specific forα-crystallin. The affinity-purified protein was compared withα-crystallins before and after crosslinking. Electron microscopy revealed sheet-like structures in the cross-linked protein from the lens extract compared with spherical structures for the others. Studies on the amino acid composition, tryptophan microenvironments and the interaction with a monoclonal antibody revealed that the complexes consist almost entirely ofα-crystallin. These results indicate that under certain conditions,α-crystallin subunits can adopt a sheet-like form.