Requires Mg2+ and is highly specific for ATP as phosphate donor [5]. The cofactors FMN and FAD participate in numerous processes in all organisms, including mitochondrial electron transport, photosynthesis, fatty-acid oxidation, and metabolism of vitamin B6, vitamin B12 and folates [3]. While monofunctional FAD synthetase is found in eukaryotes and in some prokaryotes, most prokaryotes have a bifunctional enzyme that exhibits both this activity and that of EC
2.7.1.26, riboflavin kinase [3,5].