• monoamine oxidase;
  • MAO-B;
  • imidazoline receptors;
  • platelets

Abstract: An I2 imidazoline binding site on monoamine oxidase-B (MAO-B) is known to be encoded by a noncatalytic part of the enzyme, different from that which recognizes mechanism-based inhibitors. Herein, the relationship between I2-imidazoline binding sites and MAO-B activity has been assessed using a semi-purified source of MAO-B: platelet mitochondrial membranes. A positive correlation between I2 sites and MAO-B activity was observed (r 5 0.61, P 5 0.0016) among 24 human subjects. Nevertheless, the variance in MAO-B activity cannot be completely accounted for in relation to I2 sites. Therefore, I2 density and MAO-B activity are only weakly correlated in platelets.