This book of protocols is devoted to the yellow coenzymes derived from riboflavin or vitamin B2 and to the hundreds of enzymes whose functionality depends on them, and represents a compendium of techniques for working with flavoproteins or with the wide spectrum of functions that flavoproteins can drive in the cells. Starting with Rf production in microorganisms and the chemical, optical, and redox properties of these fascinating molecules and moving along to the variety and the peculiarity of some single flavoenzymes, the volume explores the complexity of functions and distribution of these molecules in the cell. Written for the highly successful Methods in Molecular Biology series, chapters include introductions to their respective topics, lists of the necessary materials and reagents, step-by-step, readily reproducible laboratory protocols, and tips on troubleshooting and avoiding known pitfalls.