Structure and Distribution

• 5-Nucleotidase (5-NT) or CD73 is an enzyme present in various body tissues.
• Found in two types: cell membrane-bound or soluble form.
• Attached to the cell surface through glycosylphosphatidylinositol (GPI) linkage.
• Structure includes:
• N-terminal with catalytic region
• C-terminal for substrate binding
• High levels in liver, brain, heart, and skeletal muscle tissues.
• Enzyme production varies based on cell type and body conditions.

Biochemical Function and Mechanism

• Facilitates the breakdown of nucleoside 5' monophosphates into nucleosides and inorganic phosphate.
• Prefers 5' AMP substrate, converting it to adenosine.
• Enzymatic process involves a two-stage mechanism with a phosphoenzyme intermediate.
• Requires divalent metal ions like magnesium or zinc as cofactors.
• Performance influenced by substrate availability, product inhibition, and cellular energy levels.

Physiological Roles

• Significant impact on the purine salvage pathway, recycling nucleotides and maintaining cellular energy levels.
• Crucial for generating adenosine, involved in cell signalling and immune responses.
• In the nervous system, adenosine produced by 5-NT acts as a neuromodulator, influencing neurotransmission and neuronal excitability.
• Contributes to cell adhesion and migration, involved in tissue development and repair.
• Regulates inflammation and immune reactions by adjusting adenosine levels impacting immune cell functions and inflammatory agents.

Clinical Significance and Disease Associations

• Serum 5-NT recognized as an indicator in clinical settings and a target for treatment in various illnesses.
• Elevated 5-NT levels in blood indicate liver and gallbladder issues, serving as a tool for liver condition diagnosis.
• Helps distinguish whether elevated alkaline phosphatase levels are due to liver-related problems or other factors.
• In cancer research and treatment, 5-NT is linked to cancer progression and metastasis.
• Heightened presence detected in various cancers, potentially aiding immune evasion by producing adenosine within tumors.
• Linked to heart conditions, influencing blood vessel constriction and blood clotting.