NAD(P)(+)-glycohydrolase from human spleen: a multicatalytic enzyme.
NAD(P)(+)-glycohydrolase (NADase, EC 3.2.2.6) was partially purified from microsomal membranes of human spleen after solubilization with Triton X-100. In addition to NAD+ and NADP+, the enzyme catalyzed the hydrolysis of several NAD+ analogues and the pyridine base exchange reaction with conversion of NAD+ into 3-acetylpyridine adenine dinucleotide. The enzyme also catalyzed the synthesis of cyclic ADP-ribose (cADPR) from NAD+ and the hydrolysis of cADPR to adenosine diphosphoribose (ADPR). Therefore, this enzyme is a new member of multicatalytic NADases recently identified from mammals, involved in the regulation of intracellular cADPR concentration. Human spleen NADase showed a subunit molecular mass of 45 kDa, a pI of 4.9 and a Km value for NAD+ of 26 microM. High activation of ADPR cyclase activity was observed in the presence of Ag+ ions, corresponding to NADase inhibition.
Orsomando
G
G
Dipartimento di Scienze Morfologiche e Biochimiche Comparate, Università di Camerino, Italy.
Polzonetti
V
V
Natalini
P
P
D002384:Catalysis; D002413:Cations, Divalent; D004795:Enzyme Stability; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008670:Metals; D009699:N-Glycosyl Hydrolases / Q000302:isolation & purification / Q000378:metabolism*; D009244:NAD+ Nucleosidase; D013154:Spleen / Q000201:enzymology*; D013379:Substrate Specificity; D013696:Temperature
D002413:Cations, Divalent; D008670:Metals; D009699:N-Glycosyl Hydrolases; D009244:NAD+ Nucleosidase