Control Involving Adenine and Pyridine Nucleotides

Publisher Summary This chapter discusses control involving adenine and pyridine nucleotides. The adenine derivatives are employed as cofactors, or as building blocks, in a variety of metabolic functions. The adenine and pyridine nucleotides are studied mainly because of their central role in energy metabolism. The maintenance of nucleotide ratios at constant values is often considered essential for life. However, the observation of the response to light in the chloroplast stroma, or to anoxia in most cells, provides examples of large changes in adenine and pyridine nucleotide ratios, which are in contradiction with the principle of homeostasis. These changes are linked together and to other metabolite ratios either through the network of near-equilibrium reactions or by the modification of enzyme kinetics. Recent developments suggest that these changes also affect such processes as posttranslational modifications, or degradation of proteins, or the structure of membranes.