Nucleotidase is an enzyme, which is involved in the hydrolysis of a nucleotide to form a nucleoside and a phosphate. Due to this role, nucleotidase is known as a hydrolytic enzyme.
Nucleotidase plays a catalytic role in the hydrolysis process, and it converts a number of different nucleotide molecules. When nucleotidase is involved in catalysing the hydrolysis of a nucleotide, this creates a reaction as follows: a nucleotide + H2O forms a nucleoside and a phosphate. This formula can be applied to different reactions, for example converting adenosine monophosphate to adenosine and guanosine monophosphate to guanosine.
Within the body, nucleotidase plays an instrumental in the digestive system, facilitating digestion by breaking down nucleic acids.
Nucleotidase can be categorised into two groups depending on which end is hydrolyzed. These include 5’nucleotidase- also known as NT5C, NT5C1A, NT5C1B, NT5C2, NT5C3 and
3’nucleotidase- also known as NT3
5’nucleotidase is much more commonly spoken about than 3-nucleotidase. This enzyme is responsible for catalysing the phosphorolytic cleavage of 5-nucleotides. Studies suggest that this enzyme was first discovered in snake venom. However, it is found in bacteria and plant cells, as well as in vertebrates.
The primary function of 5’nucleotidase is to convert extracellular nucleotides to nucleosides. An example would be converting 5-AMP into adenosine. Once the reaction has taken place, the adenosine is able to enter almost every cell. In basic terms, nucleotidase plays an integral role in nucleotide metabolism.
The speed at which 5’nucleotidase functions is dependent on the substrate. Studies show that 5’nucleotidase hydrolyzes 5’nucleotides very quickly, with the rate slowing for ribose-5-phosphate and then decelerating even further for additional phosphate esters.
Nucleotidase Structure and mechanisms
Research suggests that the human form of 5’nucleotidase, which doesn’t have a GPI anchor, has a C-terminal, which holds the substrate-binding pouch. The purine motif of the substrate is piled between two residues of phenylalanine. This is the common structure for a soluble form. There are at least four different types of 5’nucleotidase, with 3 soluble forms and one membrane-bound structure. The membrane-bound enzyme is attached to the plasma membrane via a GPI located at the C-terminal. One of the soluble forms seems to be slightly different in that it is linked to a GPI anchor and it has an extracellular position.