Cookies on this website

We use cookies to ensure that we give you the best experience on our website. If you click 'Accept all cookies' we'll assume that you are happy to receive all cookies and you won't see this message again. If you click 'Reject all non-essential cookies' only necessary cookies providing core functionality such as security, network management, and accessibility will be enabled. Click 'Find out more' for information on how to change your cookie settings.

Salivary gland extracts from the yellow fever mosquito Aedes aegypti contain a factor Xa-specific anticoagulant detectable in vitro by clotting assays. The anticoagulant is found only in female salivary glands, which is consistent with its role in bloodfeeding. Extracts of adult female glands significantly delay both the prothrombin time and the activated partial thromboplastin time, but have no effect on the thrombin clotting time. The anticoagulant has been shown to result from the specific inhibition of coagulation factor Xa based on a FXa clotting assay and the inhibition of FXa-directed cleavage of the synthetic chromogenic substrate, chromozym X. The inhibition of FXa by female salivary gland extracts exhibits noncovalent, noncompetitive inhibition kinetics and is reversible. The anticoagulant is destroyed by boiling for 10 min or heating at 56 degrees C for 30 min, has a 4 mM calcium optimum with no magnesium requirement, and has a pH optimum of 8.0. The anticoagulant activity has an apparent molecular weight of 35.5 kDa, as determined by molecular sieve. We propose that the A. aegypti anticoagulant is a novel, proteinaceous serine protease inhibitor specific for FXa.

Original publication




Journal article


Exp Parasitol

Publication Date





321 - 331


Aedes, Animals, Blood Coagulation, Blood Coagulation Tests, Factor Xa, Factor Xa Inhibitors, Female, Humans, Insect Proteins, Insect Vectors, Male, Salivary Glands, Salivary Proteins and Peptides, Yellow Fever