Forms part of a putrescine-utilizing pathway in Escherichia coli, in which it has been hypothesized that putrescine is first glutamylated to form γ-glutamylputrescine, which is oxidized to 4-(γ-glutamylamino)butanal and then to 4-(γ-glutamylamino)butanoate. The enzyme can also catalyse the reactions of EC 18.104.22.168 (D-glutaminase) and EC 22.214.171.124 (theanine hydrolase).
Kurihara, S., Oda, S., Kato, K., Kim, H.G., Koyanagi, T., Kumagai, H. and Suzuki, H. A novel putrescine utilization pathway involves γ-glutamylated intermediates of Escherichia coli K-12. J. Biol. Chem.280 (2005) 4602–4608. [PMID: 15590624]