Polysaccharide lyase. This family includes heparin lyase I, EC:4.2.2.7. Heparin lyase I depolymerizes heparin by cleaving the glycosidic linkage next to an iduronic acid moiety. The structure of heparin lyase I consists of a beta-jelly roll domain with a long, deep substrate-binding groove and an unusual thumb domain containing many basic residues extending from the main body of the enzyme. This family also includes glucuronan lyase, EC:4.2.2.14. The structure glucuronan lyase is a beta-jelly roll.
quorum-quenching N-acyl-homoserine lactonase, MBL-fold metallo-hydrolase domain. Acyl Homoserine Lactones (also known as AHLs) are signal molecules which coordinate gene expression in quorum sensing, in many Gram-negative bacteria. Quorum-quenching N-acyl-homoserine lactonase (also known as AHL lactonase, N-acyl-L-homoserine lactone hydrolase, EC 3.1.1.81) catalyzes the hydrolysis and opening of the homoserine lactone rings of AHLs, a reaction that can block quorum sensing. These enzymes belong to the MBL-fold metallo-hydrolase superfamily which is comprised mainly of hydrolytic enzymes which carry out a variety of biological functions.
Metallo-beta-lactamase superfamily. Apart from the beta-lactamases a number of other proteins contain this domain. These proteins include thiolesterases, members of the glyoxalase II family, that catalyse the hydrolysis of S-D-lactoyl-glutathione to form glutathione and D-lactic acid and a competence protein that is essential for natural transformation in Neisseria gonorrhoeae and could be a transporter involved in DNA uptake. Except for the competence protein these proteins bind two zinc ions per molecule as cofactor.
