Schrag_1997_Methods.Enzymol_284_85

The three-dimensional structures of more than 20 representatives of the / hydrolase fold are now known and many more members have been identified by sequence and secondary structure comparisons. The fold is proving to be a common and stable way to assemble a wide variety of catalytic activities. With emphasis on lipases, this chapter reviews the features of this fold and the resources used to identify similarities in the rapidly growing number of enzymes and proteins that share this fold. The enzymes in this fold family include peroxidases, proteases, lipases, esterases, dehalogenases, and epoxide hydrolases. This fold is versatile in terms of the identities of catalytic residues and in their locations. The amino acids thus far observed as catalytic nucleophiles are serine, cysteine, and aspartate and both glutamate and aspartate have been observed as the catalytic acid. Although the acid is generally located after strand beta7, functional triads can also be constructed with the acid located after strand beta6. This fold family is also known to include proteins with no catalytic activity.