We will learn more about this in Chapter 21. Inhibitors or mutations that block specific steps in a metabolic pathway can reveal the order of steps in a pathway. Isotopic tracers and NMR spectroscopy offer methods to follow the fate of specific metabolic intermediates. Cell fractionation can be used to determine the compartmentalization of pathways. Compartmentalization of pathways is one mechanism by which competing reactions in metabolism are kept separate.
Vitamins are essential nutrients that are required in the diet, usually in trace amounts.
Except for vitamin C, all the water soluble vitamins are components or precursors of coenzymes . Coenzymes are typically recycled in enzymatic reactions, so only low levels are required. Rather than study each of these coenzymes in detail now, we will come back to each of them as we deal with enzymes that utilize these factors. Niacin deficiency causes pellagra in humans.