Biological Membranes when I moved from Shell Research to the University of Amsterdam I wanted to do some research that was different from what I was doing in Shell. Antoinette Killian (Utrecht University) pointed me at her work related to the hydrophobic mismatch of proteins embedded in a membrane. From a simulation point of view the lipids in a membrane are very similar to the surfactants I had studied in Shell. This similarity made it easy to get started. And as there were so many things I did not understand, we are still working on the same topic. 
A few things, we finally did understand better:
- With surprisingly simple ingredients one can obtain a mesocopic model that gives the correct phase diagram of some typical membranes. Our earlier work in JCP B involved membrane + water, while more recent we reported in PNAS the effect of cholesterol
- Our lipid model can also be used to study the effect of the membrane of the interactions between two membrane proteins. Most biological studies focus on the membranes, but in our work we used the freedom in molecular simulations to make a model as “unrealistic” as possible; by removing all attractive interactions between the proteins we could study the effect of the membrane in our Biophys J articles in 2005 , 2008, and 2010
Most of this work is summarized in our Physics Report