Solubilization of the lens water-insoluble fraction by sonication

A method is reported whereby the solubilization of the bulk of the lens water-insoluble fraction is accomplished by a short sonication of the suspended proteins in low salt buffers. This procedure solubilized greater than 90% of a bovine lens water-insoluble fraction and 80% of the normal human lens water-insoluble fraction. Decreased protein was solubilized from cataractous lenses, but in every case sonication was at least equivalent to extraction with 6.0 M urea. Fractionation of the solubilized proteins by Agarose A-1.5 m gel filtration chromatography showed native molecular weights for bovine lens, but only partial disaggregation with human lens extracts. A sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) comparison of the proteins solubilized by sonication and 6.0 M urea extraction showed no major differences except that sonication solubilized more of the highly cross-linked protein which remained at the top of the gel.