Water and biomolecules: an introduction

As an introduction to the eighth session ‘Water and Biosystems’ of the XVth ‘Horizon in Hydrogen Bond Research’, water molecules are presented with the stress on some elusive points which justify the existence of a session devoted to this topics. Thus, despite its familiar character, H2O is a molecule which remains still poorly known, especially when it is part of large orderless systems such as liquid water or macromolecules. It is then difficult to observe it. It has consequently for long been ignored despite the fundamental role it may play, in biosystems for instance. The central importance it has in the reactivity of aqueous sytems is evocated, with a particular emphasis on the difference between proton transfers, which are encountered in the chemistry of acid/base in water, and H atoms transfers in cyclic hydrogen bonded structures by tautomerism. Arguments are given which suggest that this latter mechanism is the basic mechanism in bioreactivity and that it is the presence of water molecules that makes it efficient. In the final part the different lectures delivered during this session are presented in the line of this viewpoint. q 2004 Elsevier B.V. All rights reserved