This volume describes some of the approaches that have been used to study enzymes in vivo. Metabolic control analysis provides a relatively simple framework with which to relate flux in a metabolic pathway to the kinetic properties of the component enzymes. More importantly it shows us how the importance of an enzyme in controlling flux in a pathway can be quantitated experimentally from measurements on the intact tissue. Fluorescence microscopy and NMR are two spectroscopic techniques which can be used to monitor, non-invasively, metabolite levels, metabolic fluxes and enzyme localization and mobility in intact biological systems. The potential of NMR for investigating the properties of enzymes in vivo has been greatly enhanced by using the technique in conjunction with molecular genetic method for changing the levels and properties of specific enzymes in the intact cell.
Control of metabolism is regarded by some as a dead subject, with little new to learn. While it is true that the chemistry of the major metabolic pathways have been fully elucidated, our understanding of how they are controlled in the cell is still rather limited. Of particular interest is the emerging evidence for a high degree of spatial organization of the supposedly 'soluble' enzymes in the cytosol and the mitochondrial matrix. Much is still to be learnt on how this organization is effected and what influence it has on control of metabolic flux. If this volume excites some interest in this area of research and, furthermore, demonstrates that these problems are eminently addressable using the new techniques which are being developed, then it will have served a useful purpose.