Abstract: The present invention uses the manganese-dependent physiological form of the enzyme methionine aminopeptidase type 2 to assess inhibition by agents that might be used in the treatment of angiogenesis, cancer, malaria and leishmaniasis. This method has the advantage of using the manganese form of the enzyme and therefore, the advantage of identifying potent inhibitors that might not show activity in cellular systems because the wrong metal cofactor is used. Therefore it is a new tool for the development of agents useful in the therapy of cancer and other angiogenesis-related diseases and, several infectious diseases including malaria, leishmaniais and microsporidiosis.