A specific, low K m ADP-ribose pyrophosphatase from rat liver

Abstract
Two rat liver ADP-ribose pyrophosphatases (ADPRibases) were partially purified. ADPRibase-I hydrolyzed ADP-ribose (K m=0.5 μM) giving AMP as a product, required Mg2+ or, less efficiently, Mn2+ (Ca2+ was not active), its activity changed little between pH 7 and 9, and was specific for ADP-ribose as it did not hydrolyze ADP-glucose, NAD+, NADH or diadenosine 5′,5″-P 1,P n -n-phosphates (Ap2A, Ap3A). ADPRibase-II showed similar properties, except that the K m for ADP-ribose was 50 μM and may be non-specific, as the same preparation hydrolyzed ADP-glucose, NADH and Ap2A. ADPRibase-I fulfils the requirements of a specific turnover pathway consistent with a cellular role for free ADP-ribose.

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