From Big Medical Encyclopedia

PROCONVERTIN (synonym: factor of VII, stable factor, cofactor thromboplastin, SPCA) — serumal accelerator of transformation of a prothrombin into thrombin. The item — a one-chained glycoprotein about a pier. it is powerful (weighing) 50000 ± 2000. The item is a necessary component of the external mechanism of a blood coagulation (see. Coagulant system of blood ). P.'s deficit leads to development of the hereditary or acquired hypoproconvertinemia (see).

The item is present normal at plasma and blood serum in an inactive form. With the participation of fabric thromboplastin (a factor of III) and calcium ions inactive P. of plasma turns in konvertiu which transforms a prothrombin (see) to thrombin (see). At a blood coagulation of P. is not consumed and remains both in plasma, and in blood serum. P.'s maintenance in plasma fluctuates from 0,1 to 1 mg/l, averaging 0,5 — 0,6 mg/l (i.e. trace concentration). At P.'s storage it is stable. The purified drug P. has the activity equal to 1800 — 2200 pieces/mg of protein.

P.'s biosynthesis happens in a liver with the participation of phthiocol. According to different researchers, the period biol. P.'s half-decay from 2 to 9 hour fluctuate. At P.'s transfusion in a blood stream the patient with hereditary insufficiency of P. time of half-decay does not exceed 30 min.

P.'s activity is established by test of Deysi based on definition of a prothrombin time (see) on Kvika. The principle of a method is based that at addition of long stored (old) blood serum of the donor (a source of proconvertin) to the fresh studied blood plasma with the extended time on Kvika, the last is sharply shortened that indicates P.'s deficit in the studied plasma. Quantitative definition of activity of P. is made on time of a svertyv a niya of divorced rekaltsifinirovanny citrate plasma investigated in the presence of the plasma deprived of P. (the bull plasma or fresh plasma of the donor filtered through asbestos plates of the filter of Zeytts). During the definition of deficit of P. use also drugs of snake poison — - stipven or lebetoks in mix with kephalin which normalize time of coagulation of rekaltsifinirovanny plasma of the patient.

Bibliography: Barkagan 3. C. Hemorrhagic diseases and syndromes, M., 1980; Kudryashov B. A. Biological problems of regulation of liquid state of blood and its coagulation, M., 1975; The Reference book on clinical laboratory methods of a research, under the editorship of E. A. Kost, M., 1975; Alexander B., V of of i e s A. Goldstein R. Factor in sérum which accelerates conversion of prothrombin to thrombin, Blood, v. 4, p. 739, 1949; Bajaj S. P., Rapaport S. I. a. Brown S. F. Isolation and characteri-zation of human factor VII, J. biol. Chem., v. 256, p. 253, 1981; Kisiel W. McMullen B. A. Isolation and cha-racterization of human factor Vlla, Throm-bos. Res., v. 22, p. 375, 1981; M about r r i-son-Silverberg S. A. a. Jes-t y J. The rôle of activated factor X in the control of bovine coagulation factor VII, J. biol. Chem., v. 256, p. 1625, 1981; About w e n of Page A. a. In about 1 1 m a n J. L. Prothrombin conversion factor of dicuma-rol plasma, Proc. Soc. exp. Biol. (N. Y.), v. 67, p. 231, 1948; Owren P. A. La proconvertine, Rev. Hémat., t. 7, p. 147, 1952.

H. Ya. Lagutina.