Morphological and mechanical studies of cholesterol monolayer on aqueous solution of Vibrio cholerae hemolysin

The action of Vibrio cholerae hemolysin (VCH) on cholesterol monolayer was investigated on the basis of area strain measurements and atomic force microscopic observations of the monolayer. The area strain-time behavior of the monolayer by addition of VCH was mainly classified into the two processes in shorter and longer time ranges with respect to around 2.0 × 103 s. The area strain in a long time range decreased remarkably, that is, the monolayer expanded owing to the penetration of VCH subunits into the monolayer and the gathering growth of them.