A three-component membrane-bound flavoenzyme that catalyzes the formation of hydrogen cyanide, a secondary metabolite, by transfer of electrons to a cyanide-resistant branch of the aerobic respiratory chain. 2 A + glycine = 2 AH2 + CO2 + hydrogen cyanide Oxygen is necessary for cyanogenesis. Activated by succinate, glycine methyl ester, glucose and D,L-methionine in addition to glycine. Phenazine methosulfate, methylene blue, 2,6-dichlorophenolindophenol (DCIP) and ferricyanide can replace oxygen for the reaction. Inhibited by pyrrolnitrin and acriflavine at 1 mM concentration. Measured for the whole complex. Optimum pH is 8.3 (in the presence of Tris-HCl). Active from 7.3-7.8 in the presence of other buffers. Not stable at 0 degrees Celsius. Decrease in activity up to 40% immediately after freeze-drying procedure, with a further decrease up to 10% when stored at -10 degrees Celsius. Heterotrimer of HcnA, HcnB and HcnC. Reduced oxygen levels. Belongs to the FAD-dependent glycerol-3-phosphate dehydrogenase family.