Biochemical pathways energy transformations

These examples served to show that the Biochemical Pathways database provides a rich source of information on these all important reactions that determine the transformation of nutrients into the broad spectrum of compounds contained in living species and the concomitant production of energy to keep these processes going. 

Fig. 3-4 The biochemical pathway of glycolysis, which obtains energy from the breakdown of 6-carbon sugars to a pair of 3-carbon pyruvate molecules. The enzymes at each reaction in the sequence are in italics. The energy generated is stored in the form of ATP (see Fig. 3-5). Pyruvate can be further transformed to lactate or ethanol under anaerobic conditions (fermentation), or, under aerobic conditions, it can enter the TCA cycle (see Fig. 3-10).

Bioenergetics provides a quantitative description of the transformation of materials and energy in living systems. Most biochemical reactions occur in pathways, in which other reactions continuously add substrates and remove products. The rate of reactions depends on the properties of the enzymes (large proteins produced in cells) that catalyze the reaction. Substrates bind at the active sites of enzymes, where they are converted to products and later released. Enzymes are highly specific for given substrates and products. Inhibitors of enzymes decrease the rate of reaction. 

Pathways of metabolism have been outlined which indicate how tryptophan is a source of auxin, niacin, serotonin, ommochrome, and energy. Many other compounds are formed as side-products of these pathways and still others are formed by further reactions. Yet additional pathways remain to be elucidated to describe the formation of gramine (V-dimethyl-indole-3-methylamine), abrine (A -methyltryptophan), the a-hydroxy-tryptophan component of phalloidin, skatole, and possibly other complex compounds containing the indole nucleus. The reactions involved in these transformations include examples of various types of oxidation, transamination, cleavage, elimination, decarboxylation, and condensation as well as cis-trans isomerization. The wealth of biochemical variety already revealed in these studies is a stimulus toward exploration of the still unknown reactions of tryptophan metabolism. 

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