This domain is predicted to be an enzyme [1] and is often found associated with Pfam:PF01476. It's structure consists of a beta-sandwich surrounded by two helices and two one-turn helices [2].

1: Systematic identification of novel protein domain families associated with nuclear functions. Doerks T, Copley RR, Schultz J, Ponting CP, Bork P; Genome Res 2002;12:47-56. PMID:11779830

2: Crystal structure of the TLDc domain of oxidation resistance protein 2 from zebrafish. Blaise M, Alsarraf HM, Wong JE, Midtgaard SR, Laroche F, Schack L, Spaink H, Stougaard J, Thirup S; Proteins. 2012;80:1694-1698. PMID:22434723