Anticoagulant of blood sucking insect salivary glands

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We have analyzed physiologically active compounds from the salivary glands of blood suckinh insect, Rhodnius prolixus. We found two different anti-coagulant activities from the extract of Rhodnius salivary glands by analyzing activated partial thromboplastin time (APTT) and prothrombin time (PT). Our analyzes showed inhibitory activities of both intrinsic pathway, Xase complex and common pathway, thrombin (factor lla) in the coagulant cascade.We focussed our analyzes on the Xase inhibitor, and tried to purify and characterize. This inhibitor is a hemeprotein with molecular weight of about 20 kDa. We named it Prolixin-S.Prolixin-S has an inhibitory activity of factor X activation, i.e.Xase complex, which include factor IX,VIII,phospholipid and Ca. We are studying on the mechanism of Xase complex blocking with Prolixin-S.Prolixin-S cDNA was cloned from Rhodnius salivary gland cDNA library with polyclonal antibody to Prolixin-S,and sequenced. Prolixin-S was expressed by baculovirus insect cell expression system and purified chromatographically. Recominant Prolixin-S had anticoagulant activity as almost same level as native Prolixin-S.rProlixin-S was easily reconstituted as heme-protein with hemine and can be bound nitric oxide (NO) reversiblly. NO bound prolixin-S has a vasodilation activity to rabbit vascular smooth muscle. This molecule, Prolixin-S,is a unique protein which has both anti-coagulant activity and vasodilating activity.