Proclavaminate 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))  

Arginine is capable of binding in the active site of PAH but it is not an enzyme substrate. Crystal structures of PAH from Streptomyces clavuligerus show that the metal binding site is very similar to that of arginase and the Mn—Mn distance is 3.3 A The main difference between arginase and PAH is in the binding pocket at the o-amino-terminus of the substrate.  

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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.

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