Genes for Energy-Related Proteins

Abstract

Proteins and protein systems involved directly with the production or employment of such energy-storing molecules as ATP and the other triphosphorylated nucleosides are of numerous types. Some of these form large families, such as the familiar cytochromes, while others comprise small groups of related varieties, and still others work as clusters of diversified composition. But even the large family just cited, the cytochromes, are not unified as to their specific function. Although all conduct electrons, the best known members of that group comprise the greater portion of an electron-transport chain whose end product is ATP or kin substance, but others, notably the cytochromes P-450, are concerned with syntheses that break down that type of nucleoside to liberate required energy. Still another category of energy-using compounds contains the varied components of a group involved in using such energy to convert free nitrogen into ammonia and thereby “fix” that element. Thus this chapter centers both on substances that create stores of energy and others that draw upon that supply. No relationship between the several classes involved here is to be expected; their sole common denominator is a direct interaction with high-energy nucleosides. But the possibility that this varied lot may show some features in common nevertheless needs to be explored—the two unrelated classes examined in the preceding chapter certainly were found to share some very significant traits.