Coagulation Factors: Nomenclature, activation, and key properties

Notes

• Secondary Hemostasis **Coagulation Factors** Factors are assigned Roman numerals and are numbered roughly in the order of their discovery. When a procoagulant enzyme is activated, a lowercase “a” appears after the numeral; for example, activated factor VII. These factors are pro-coagulants and are produced mainly by the liver, except for factors II, V, and the alpha subunit of factor XIII. **Antihemophilic Factor** Factor VIII is known as the antihemophilic factor (AHF). It consists of eight enzymes: seven serine proteases and one transglutaminase. Factor VI was originally thought to be an activated form of Factor V, but it is non-existent. **Common Characteristics of Coagulation Factors** A deficiency in any of these factors generally results in a bleeding tendency disorder, with the exception of factors XII, prekallikrein (Fletcher factor), and high-molecular-weight kininogen (HMWK; Fitzgerald factor). The physical and chemical characteristics of each factor are well known, and their synthesis is independent of other proteins. Additionally, these factors can be assayed in the laboratory. **Numeral, Preferred Name, and Synonyms/Alternative Names** - I: Fibrinogen (Prethrombin) -...