In enzymology, a ADP-ribosyl cyclase/cyclic ADP-ribose hydrolase () is a bifunctional

enzyme Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products ...

that catalyzes the

chemical reaction A chemical reaction is a process that leads to the IUPAC nomenclature for organic transformations, chemical transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the pos ...

:NAD⁺ + H₂O

\rightleftharpoons

cADPR + H₂O + nicotinamide

\rightleftharpoons

ADP-ribose + nicotinamide The 3 substrates of this enzyme are NAD⁺ and H₂O, whereas its two

products Product may refer to: Business * Product (business), an item that serves as a solution to a specific consumer problem. * Product (project management), a deliverable or set of deliverables that contribute to a business solution Mathematics * Produ ...

are

ADP-ribose Adenosine diphosphate ribose (ADPR) is an ester molecule formed into chains by the enzyme poly ADP ribose polymerase. ADPR is created from cyclic ADP-ribose (cADPR) by the CD38 enzyme using nicotinamide adenine dinucleotide (NAD+) as a cofactor. ...

and

nicotinamide Niacinamide or Nicotinamide (NAM) is a form of vitamin B3 found in food and used as a dietary supplement and medication. As a supplement, it is used by mouth to prevent and treat pellagra (niacin deficiency). While nicotinic acid (niacin) may ...

. The reaction proceeds through

cyclic ADP-ribose Cyclic ADP Ribose, frequently abbreviated as cADPR, is a cyclic adenine nucleotide (like cAMP) with two phosphate groups present on 5' OH of the adenosine (like ADP), further connected to another ribose at the 5' position, which, in turn, closes ...

(cADPR) as intermediate, which is then hydrolyzed into

. This makes it different from NAD⁺ glycohydrolase (EC 3.2.2.5), where the reaction does not proceed through cADPR. This enzyme belongs to the family of

hydrolase Hydrolase is a class of enzyme that commonly perform as biochemical catalysts that use water to break a chemical bond, which typically results in dividing a larger molecule into smaller molecules. Some common examples of hydrolase enzymes are este ...

s, specifically those glycosylases that hydrolyse N-glycosyl compounds. Other names of this enzyme in common use include nicotinamide adenine dinucleotide (phosphate) nucleosidase, triphosphopyridine nucleotidase, NAD(P) nucleosidase, NAD(P)ase, and nicotinamide adenine dinucleotide (phosphate) glycohydrolase. This enzyme participates in

nicotinate and nicotinamide metabolism Nicotinamide adenine dinucleotide (NAD) is a coenzyme central to metabolism. Found in all living cells, NAD is called a dinucleotide because it consists of two nucleotides joined through their phosphate groups. One nucleotide contains an aden ...

References

* * * EC 3.2.2 NADPH-dependent enzymes NADH-dependent enzymes Enzymes of unknown structure {{3.2-enzyme-stub