This domain is found in toxoflavin-degrading enzymes such as toxoflavin lyase (TflA) also known as toxoflavin-degrading enzyme (TxDE). TflA/TxDE is structurally similar to the vicinal oxygen chelate superfamily of metalloenzymes, despite the lack of apparent sequence identity [1, 2].

1: Toxoflavin lyase requires a novel 1-His-2-carboxylate facial triad. Fenwick MK, Philmus B, Begley TP, Ealick SE; Biochemistry. 2011;50:1091-1100. PMID:21166463

2: Structural and functional analysis of phytotoxin toxoflavin-degrading enzyme. Jung WS, Lee J, Kim MI, Ma J, Nagamatsu T, Goo E, Kim H, Hwang I, Han J, Rhee S; PLoS One. 2011;6:e22443. PMID:21799856