Oxidative deamination is an oxidation reaction, which occurs under aerobic conditions in most tissues, and occurs largely on glutamic acid residues since glutamic acid is the end product of many transamination reactions. Oxidative deamination is also known to cause the loss of the amino groups of lysine and has been identified in oxidized proteins.
While enzymatic forms of this reaction are important in maintaining nitrogen balance, oxidative deamination can also occur as an enzymatic reaction, where the deamination of lysine can be catalyzed by the enzyme lysine oxidase. Oxidative deamination is also the first step in the breakdown of norleucine and structurally related non-standard amino acids such as norvaline, beta-methylnorleucine, and homoisoleucine.
For example, oxidative deamination of norleucine would yield ketocaproic acid and ammonia.
Akagawa et al., used model reactions of benzylamine to elucidate oxidative deamination by glycoxidation.
The oxidative reaction was inhibited by EDTA, catalase, and dimethyl sulfoxide,
suggesting the participation of reactive oxygen species in this process. They proposed a
Strecker-type reaction and reactive oxygen species-mediated oxidation during
glycoxidation as a mechanism for oxidative deamination.
When the enzyme lysyl oxidase crosslinks collagen, for example, hydrogen peroxide is released. However, enzymatic deamination reactions involving oxidases may be attenuated by endogenous protective mechanisms.