Morawitz believed that his enzyme came from cells such as platelets yet, in keeping with the state of knowledge about enzymes at that time, he had no clear idea about the chemical nature of his thrombokinase or its mechanism of action. Those uncertainties led to decades during which the terms thrombokinase and thromboplastin were both used to describe the activator of prothrombin and led to controversy about its chemical nature and origin.In 1947, J Haskell Milstone isolated a proenzyme from bovine plasma which, when activated, converted prothrombin to thrombin. Following Morawitz’s designation, he called it prothrombokinase  and by 1951 had purified the active enzyme, thrombokinase. Over the next several years he showed  that thrombokinase was a proteolytic enzyme that, by itself, could activate prothrombin. Its activity was greatly enhanced by addition of calcium, other serum factors, and tissue extracts, which represented the thromboplastins that promoted the conversion of prothrombin to thrombin by their interaction with thrombokinase. In 1964 Milstone summarized his work and that of others: “There are many chemical reactions which are so slow that they would not be of physiological use if they were not accelerated by enzymes. We are now confronted with a reaction, catalyzed by an enzyme, which is still too slow unless aided by accessory factors.”

Interactions
Factor X has been shown to interact with Tissue factor pathway inhibitor. References
External links
The MEROPS online database for peptidases and their inhibitors: S01.216
med/3495 at eMedicine
Factor X deficiency


== Further reading ==
History
The introduction and use of ampicillin alone started in 1961. The development and introduction of this drug allowed the use of targeted therapies against gram-negative bacteria. With the rise of beta-lactamase producing bacteria, ampicillin and the other penicillin-derivatives became ineffective to these resistant organisms. With the introduction of beta-lactamase inhibitors such as sulbactam, combined with ampicillin made beta-lactamase producing bacteria susceptible. Formulation
Ampicillin-sulbactam only comes in a parenteral formulation to be either used as intravenous or intramuscular injections, and can be formulated for intravenous infusion. It is formulated in a 2:1 ratio of ampicillin:sulbactam. The commercial preparations available include:
1.5 grams (1 gram ampicillin and 0.5 gram sulbactam)→Brand names: Unasyn, Unasyn ADD-Vantage, Unasyn Piggyback

3 grams (2 grams ampicillin and 1 gram sulbactam)→Brand names: Unasyn, Unasyn ADD-Vantage, Unasyn Piggyback

15 grams (10 grams ampicillin and 5 grams sulbactam)→Brand name: Unasyn

Society and culture
Names
Unasyn (US)
Subacillin (Taiwan)
Unictam (Egypt)
Ultracillin (Egypt)
Fortibiotic
Sulbin (Egypt)
Novactam (Egypt)
Sulbacin (Kenya)

References
External links
"Ampicillin mixture with Sulbactam". Drug Information Portal. U.S. National Library of Medicine.