“…In most flavin-linked dehydrogenases the flavin adenine nucleotide is a tightly bound prosthetic group. In CII, it is even covalently and thus permanently bound to the enzyme during the catalytic cycle when the redox state is regenerated in each enzymatic turnover, as documented in early reports ( 35 ) and summarized in classical textbooks ( 36 , 37 ). Structural studies of CII have expanded our knowledge of the mechanism of enzyme assembly ( 13 ), enzyme structure ( 38 , 39 , 40 ), kinetic regulation of CII activity ( 41 , 42 ), and associated pathologies ( 3 , 26 , 27 , 28 , 29 ).…”