Resumen de It costs more than a nickel
Biology class teaches us that enzymes are proteins, but many enzymes rely on supplementary nonprotein cofactors for catalytic activity. Some enzyme active sites contain elaborate auxiliary components that provide chemical versatility well beyond the capabilities of naked proteins. Such enzymes often require a lot of extra effort to prepare, entailing synthesis and/or mobilization of multiple scarce components. On page 66, Desguin et al. (1) show that the catalytic center at the active site of lactate racemase contains both a prosthetic group derived from nicotinic acid (vitamin B3) and a nickel ion. This organometallic cofactor bears several features that have not been seen before in nature and raises questions about both the biosynthesis and the catalytic reactivity.
