Summary
Although thrombin formed in product I generating mixtures, product I and thrombin
activity were essentially uncorrelated. The addition of thrombin to generating mixtures
caused acceleration of product I formation, but failed to elicit product I formation
in “incomplete” systems. Product I was found to be relatively stable when formed with
diluted reagents or separated from certain plasma proteins. When inactivation occurred
with concentrated reagents, activity was restored only with further addition of reagents
containing AHF. The stability of product I at 57° C is similar to that of AHF. When
product I is reacted with a source of phosphatide to form blood thromboplastin, little
product I “consumption” occurs.