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A high school [secondary, prep school] teacher asked me [Geo] for a definition of thrombokinase. It sounded familiar, but I couldn’t place it so I checked some online dictionaries. One wrote it was the same as platelet factor 3, which the dictionary misnamed platelet factor III; another said it was activated factor X, and yet another called it a synonym for tissue thromboplastin. I checked some old textbooks, including the late Dr. Douglas Triplett’s famous 1982 “Laboratory Evaluation of Coagulation,” which still appears on every “clotter’s” shelf. The term is not in the book, nor is it in my own 1988 text, “Hemostasis and Thrombosis in the Clinical Laboratory,” edited with Dr. Donna Corriveau. Neither does it appear in Bennington’s comprehensive 1984 “Dictionary and Encyclopedia of Laboratory Medicine and Technology.” This is a great reference that should have been kept current through the years. I finally found one obscure reference to thrombokinase on page 100 of Dr. J. Ferguson’s 1960 “Lipoids and Blood Platelets.” Ferguson refers to it as a rabbit brain extract thromboplastin “kindly supplied by [prothrombin time developer] Dr. Armand Quick.” Dave McGlasson also found it in the 2001 edition of “Stedman’s Concise Medical Dictionary for the Health Professions.” So it appears to be a synonym for tissue thromboplastin, a preparation that has been largely, though not totally replaced by the prothrombin time thromboplastin reagent composed of synthetic tissue factor and phosphatidyl serine.

Meanwhile, for our “mature” participants, let’s see who can match the current Roman numeral to some obsolete names, listed in no particular order:

  1. Proaccelerin
  2. Proconvertin
  3. Labile factor
  4. Accelerator globulin
  5. Stable factor
  6. Serum prothrombin conversion accelerator
  7. Autoprothrombin I
  8. Platelet cofactor I
  9. Plasma thromboplastin component
  10. Christmas factor
  11. Autoprothrombin II
  12. Platelet cofactor II
  13. Platelet factor 3
  14. Stuart-Prower factor
  15. Stuart factor
  16. Autoprothrombin III
  17. Plasma thromboplastin antecedent
  18. Antihemophilic factor C
  19. Hageman factor
  20. Fibrin stabilizing factor
  21. Fibrinase
  22. Laki-Lorand factor
  23. Fletcher factor
  24. Fitzgerald factor
  25. Flaujeac factor

No cash prizes, just the satisfaction of having a good memory!

Comments (3)
Coagulation Factors
Jul 1, 2020 7:38am

From Ali Sadeghi-Khomami, PhD
From Ali Sadeghi-Khomami, PhD, Precision BioLogic Inc, Halifax NS:

I have to admit you got me on this one! It took me a while until I realized how a thromboplastin kindly supplied [thrombokinase] could emerge in the literature. The Intenz site, has high reputation in bioinformatics:
So apparently, a non phosphorylated enzyme as a thrombokinase really exists! Still I’m in loss to make any connection between factor Xa [serine protease] and a kinase (phosphorylating) enzyme though. PS. I have not checked out references listed in the site myself but a Google search showed a high level of disagreement. This is why we love coag!

Jul 1, 2020 7:32am

Larry Brace, PhD, Coagulation
Larry Brace, PhD, Coagulation Consultants, Chicago, challenges us with an additional teaser:
So, what is the difference between a synthase and a synthetase? One requires energy input (ATP) and one does not. Which is which?

Jul 1, 2020 7:30am

Received via email from
Received via email from Jeanine Walenga, PhD, Loyola University Medical Center, Chicago:

Hello George!
I looked at my home library and found a book by Quick published in 1957, Lea & Febiger (USA), Hemorrhagic Diseases. This book had belonged to Dr. Harry Messmore (bless his soul).

To answer the thrombokinase question, page 37 in the section “The Conversion of Prothrombin to Thrombin in Plasma” states:
“Schmidt [1893-1895, Germany] was probably the first to recognize that tissue extract when added to blood hastened coagulation. The term zymoplastic substance which he applied to this activity was changed by Morawitz [1904, Germany] to thrombokinase and by Fuld and Spiro [1904, Germany] to cytozyme… In this country [USA], Howell [1912] coined the term thromboplastin. It originally meant the factor which removed the inhibitor from prothrombin but gradually it merely became the name for the clotting factor or factors in extracts of various tissues. Opinion is still divided as to whether it is a reactant or an enzyme and the available information is insufficient to establish either view.”

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