IntBioSim is a BBSRC funded project involving the universities of Oxford, Southampton, Bristol, Manchester, and London (UCL). The project will develop an integrated approach to computational systems biology spanning from chemical to cell biological simulations. This approach will be applied to a pharmaceutically important class of proteins, namely monotopic membrane-bound enzymes, e.g. cyclooxygenases and monoamine oxidase. The key e-Science objective of this project is to develop a generic framework within which to conduct multi-level biomolecular simulations. The project will address two areas: (i) development of a biomolecular simulation markup language to enable a hierarchical approach to multi-level simulations; and (ii) development of approaches to computational steering and coupling simulations on heterogeneous resources to enable a hybrid approach. The project will also evaluate the relative performance of hierarchical vs. hybrid approaches to multi-level biomolecular simulations in a GRID environment.