N-terminal lipase phosphatase domain of human soluble epoxide hydrolase, Escherichia coli YihX/HAD4 alpha-D-glucose 1-phosphate phosphatase, and related domains, may be inactive
This family includes the N-terminal phosphatase domain of human soluble epoxide hydrolase (sEH). sEH is a bifunctional enzyme with two distinct enzyme activities, the C-terminal domain has epoxide hydrolysis activity and the N-terminal domain (Ntermphos), which belongs to this family, has lipid phosphatase activity. The latter prefers mono-phosphate esters, and lysophosphatidic acids (LPAs) are the best natural substrates found to date. In addition this family includes Gallus gallus sEH and Xenopus sEH which appears to lack phosphatase activity, and Escherichia coli YihX/HAD4 which selectively hydrolyzes alpha-Glucose-1-P, phosphatase, has significant phosphatase activity against pyridoxal phosphate, and has low beta phosphoglucomutase activity. This family belongs to the haloacid dehalogenase-like (HAD) hydrolases, a large superfamily of diverse enzymes that catalyze carbon or phosphoryl group transfer reactions on a range of substrates, using an active site aspartate in nucleophilic catalysis. Members of this superfamily include 2-L-haloalkanoic acid dehalogenase, azetidine hydrolase, phosphonoacetaldehyde hydrolase, phosphoserine phosphatase, phosphomannomutase, P-type ATPases and many others. HAD hydrolases are found in all three kingdoms of life, and most genomes are predicted to contain multiple HAD-like proteins. Members possess a highly conserved alpha/beta core domain, and many also possess a small cap domain, the fold and function of which is variable. HAD hydrolases are sometimes referred to as belonging to the DDDD superfamily of phosphohydrolases.