Properties of Heated Chick Embryo Extracts When Activated

Abstract

The writer has found that addition of one volume rabbit plasma to 60-100 volumes chick embryo extract greatly increases the coag-ulative power of the extract 1 ; that the increase in power is due to a body which reacts like thrombin in regard to the calcium ion 2 ; that the plasma factor involved is prothrombin 3 ; that the extract factor has the heat stability of cephalin and that the heated extract is as susceptible to activation as the unheated. 4 (Degree of activation calculated according to the method of Mills. 5 )

Further study has brought out the fact that the time at which activation occurs is closely correlated with the clotting power of the extract being activated (as measured by its power to shorten the coagulation time of a recalcified citrate rabbit plasma). There appears, however, to be no such correlation between the coagulative power of such an extract and the degree of activation.

Determinations of coagulative power and activation were done as described above. 4 In that paper it was reported that there was a marked decrease in the coagulative power of chick extract as heating was done at intervals of 10°C. and that the decrease was especially marked below 60°. Above this point the power is relatively stable at a much lower level.

With the decrease in coagulative power of the extract there is a lengthening of the latent period of activation. In a typical experiment 0.05 cc. fresh unheated extract shortened the coagulation time of a recalcified citrate plasma from 15 min. to 1 min. 30 sec; activation required 4 min. 35 sec. After heating until the coagulation time increased from 1 min. 30 sec. to 7 min. the activation required 37 min.