Figure 3 of Gupta, Mol Vis 2010; 16:2242-2252.

Figure 3. Assay of protease activity in the βA3-crystallin following treatment with CHAPS or Triton X-100. Following treatment of βA3-crystallin preparation (50 μg) with either CHAPS or Triton X-100 and incubation with BAPNA as a substrate, only the CHAPS-treated crystallin exhibited protease activity. The protease activity increased during incubation for 24 h at 37 °C as indicated by the release of p-nitroaniline (yellow) from BAPNA, which was monitored at 405 nm.