Salivary homogenates of the adult female mosquito Anopheles albimanus

array of antihemostatic chemicals (Ribeiro, 1987, 1995), including anticlotting, antiplatelet and vasodilatory substances. Interestingly, the solutions found by each arthropod species to counteract each aspect of their host hemostasis are very different, perhaps as a result of evolutionary convergence. For example, vasodilators found in the saliva or salivary homogenates of such animals include the inorganic molecule nitric oxide (NO) in the bugs Rhodnius prolixus and Cimex lectularius (Ribeiro et al., 1993; Valenzuela et al., 1995), lipids of the prostaglandin class in the tick Boophilus microplus (Dickinson et al., 1976; Higgs et al., 1976) and Amblyomma americana (Ribeiro et al., 1988, 1992) and unrelated peptides in the mosquito Aedes aegypti (Champagne and Ribeiro, 1994), the sand fly Lutzomya longipalpis (Lerner and Shoemaker, 1992) and the black fly Simmulium vittatum (Cupp et al., 1998). The mosquito Anopheles albimanus has a salivary peroxidase that displays catechol oxidase activity (i.e. it destroys catecholamines in the absence of added hydrogen peroxide). This activity has been implicated in the relaxation induced by salivary homogenates of aortic smooth muscle contracted with norepinephrine (Ribeiro and Nussenzveig, 1993). In the present study, we report the purification of the salivary peroxidase of A. albimanus and demonstrate that the pure enzyme can cause vasodilation of rabbit aortic rings contracted with norepinephrine. Amino-terminal sequencing of the pure enzyme allowed cloning and sequencing of the peroxidaseencoding cDNA, which shows high homology to vertebrate and invertebrate peroxidases of the myeloperoxidase family.