▁and ▁properties ▁ ▁While ▁D - am ino ▁acid ▁ox id ase ▁diff ers ▁to ▁some ▁extent ▁between ▁various ▁organ isms , ▁the ▁structure ▁is ▁basically ▁the ▁same ▁across ▁most ▁e uk ary otes , ▁ex cluding ▁plants . ▁This ▁en zym e ▁is ▁a ▁flav op rote in ▁belonging ▁to ▁the ▁F AD ▁dependent ▁ox id ored uct ase ▁family , ▁and ▁acts ▁on ▁the ▁CH - N H 2 ▁group ▁of ▁D - am ino ▁acid ▁don ors ▁with ▁o xygen ▁as ▁accept or . ▁It ▁is ▁also ▁considered ▁a ▁per ox is om al ▁en zym e ▁containing ▁F AD ▁as ▁a ▁c of actor . ▁Each ▁DA O ▁mon omer ▁has ▁an ▁F AD - binding ▁domain ▁( FB D ) ▁containing ▁a ▁Ross mann ▁fol d , ▁and ▁a ▁substr ate - binding ▁domain ▁( SB D ) ▁that ▁also ▁forms ▁an ▁interface ▁with ▁the ▁other ▁mon omer ▁in ▁the ▁protein . ▁DA O ▁exists ▁as ▁a ▁dim er , ▁with ▁each ▁mon omer ▁containing ▁both ▁an ▁FB D ▁and ▁S BD . ▁Each ▁mon omer ▁is ▁composed ▁of ▁ 3 4 7 ▁am ino ▁ac ids ▁in ▁human ▁DA O , ▁though ▁among ▁other ▁e uk ary otes ▁the ▁protein ▁can ▁range ▁from ▁ 3 4 5 ▁to ▁ 3 6 8 ▁am ino ▁ac ids ▁long . ▁In ▁human ▁DA O , ▁the ▁two ▁mon om ers ▁are ▁connected ▁in ▁a ▁head - to - head ▁fashion . ▁DA O ▁of ▁other ▁organ isms , ▁such