This category groups enzymes having the EC number 1.1.99, corresponding to oxidoreductases acting on the CH-OH group of donors with other acceptors, i.e., those not found in the earlier 1.1.# classes. For example, EC 1.1.1 enzymes used NAD or NADP as the acceptor, whereas 1.1.2 and 1.1.3 enzymes use cytochromes and oxygen, respectively.

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