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Further Work

The results presented in this thesis indicate that the future for ab initio computational simulations in biological disciplines is extremely promising. Several avenues of investigation of the cytochrome P450 enzyme system are immediately suggested. Further steps in the catalytic cycle, including the reduction of the system by its redox partners and the binding of tex2html_wrap_inline2954 at the active site, may be explored. This would offer information about intermediary states in the catalytic cycle which are not directly accessible to conventional experimental techniques. Such simulations could also permit the calculation of reaction rates which are thought to be limited by the rate of the second reduction of the active site complex (See Chapter gif). A scheme for predicting the action of a cytochrome P450 enzyme on a given molecule would be of enormous benefit to the pharmaceutical industry. Such a tool would offer savings in time and money in the development of potential drug compounds which must be tested for their activity with cytochrome P450 enzymes. Any approach to predictive simulations would obviously require the consideration of the specificity of human cytochrome P450s. This in turn requires accurate models of the geometry of the active sites of these enzymes which is are subjects of current investigations (see for example [132] and [133]). Ab initio simulations may also have a rôle to play in these investigations. Comparison of experimental observations with calculated reaction characteristics for a ligand in different orientations within the active site would allow models of the active site structure to be tested. Using current ab initio methods, the computational power is not available to thoroughly explore questions of substrate specificity and orientation within the active site. This is because a large number of possible configurations must be tested to determine the optimum orientation of a ligand or even if it will bind at all. However, these searches may be efficiently performed using empirical approaches, although these are less accurate than ab initio methods. It is possible that the use of ab initio techniques in combination with empirical fast-search methods might provide a suitable methodology to solve this problem. A quick empirical search could suggest a few candidate ligand orientations which would then be studied in detail using ab initio simulations to compare their energies and model the reaction mechanism.

Although the cytochrome P450 enzyme system offers an ideal target for ab initio modeling, there are many other enzymes and receptors which could be studied. With the increases in available computer power predicted over the next few years, the possible applications of ab initio computer simulations are almost boundless.


next up previous contents
Next: Implementation of Population Analysis Up: Conclusion Previous: Summary of Thesis

Matthew Segall
Wed Sep 24 12:24:18 BST 1997