163 205 1985 as a result the phospholipid dependent blood coagulation reactions are inhibited by vac on the basis of its mechanism of activity vac can be categorized in group 3 described above however a critical difference between vac and the other known proteins of this group is that vac does not hydrolyze phospholipids and therefore does not decompose any essential membrane structures among the properties of vac which have not hitherto been described for any of the known anti coagulants is the fact that the anti coagulation effect of vac is dependent on the concentration of phospholipids in the coagulation process this dependency means that the coagulation process which has been initiated for example by slight damage to the wall of the blood vessel and or by slight activation of blood platelets that is by a thrombotic process can be inhibited by vac on the other hand the coagulation process which is triggered by severe damage to walls of blood vessels wherein phospholipids are present in high concentrations is not inhibited by vac because of high phospholipid concentrations the danger of severe bleeding when using vac is therefore extremely small this property of vac is in contrast to all the previously known anti coagulants which render one or more of the coagulating factors ineffective and thereby increase the risk of severe bleeding another surprising property of vac is that it does not deactivate the coagulating factors themselves consequently the coagulating factors can still perform their other functions for example some active coagulating factors also play a non hemostatic role in the chemotaxis of the inflammatory cells which participate in the repair of damaged blood vessel walls this invention further describes.