Hydrolase amidino

Scheme 10.30 Part of clavulanic acid biosynthesis. Bonds installed byclavaminic acid synthase (CAS) are circled. CAS clavaminic acid synthase. PAH proclavaminic acid amidino hydrolase.

Proclavaminate amidino hydrolase (PAH) is one of a number of enzymes that are Mn activated and whose amino acid sequence shows strong homology with arginase. PAH catalyzes the hydrolysis of a guanidino group to give proclavaminate and urea (Equation (8)) ... 

This enzyme [EC 3.S.3.4], also called allantoate amidino-hydrolase, catalyzes the hydrolysis of allantoate to produce (-)-ureidoglycolate and urea. The enzyme can also catalyze the hydrolysis of (+)-ureidoglycolate to generate glyoxylate and urea. 

The functions of the guanidine-modifying enzymes further subdivide the family into three distinct groups hydrolases, dihydrolases, and amidinotransferases. Hydrolases catalyze the hydrolysis of guanidine derivatives to form ureido compounds, whereas dihydrolases catalyze a hydrolysis reaction to yield a primary amine, ammonia, and bicarbonate (or carbon dioxide). The amidinotransferases transfer an amidino group from one substrate to an amine. Although these are distinct reactions, they are characterized by common structural and mechanistic themes. 

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