438 VITAMIN K GROUP 



since Lyons'^ found evidence for a quinone structure in thrombin. The 

 consensus, however, is that vitamin K does not actually constitute a part 

 of the prothrombin molecule. Dam and associates'^ were unable to find 

 any vitamin K activity in refined prothrombin preparations. Quick'' has 

 calculated that the amount of vitamin K which will raise the plasma pro- 

 thrombin is significantly less than 1 mole for each mole of prothrombin 

 (assuming a prothrombin molecular weight of 140,000'^ and concentration 

 of 20 mg. per 100 ml. in the plasma).'* Such calculations have no meaning 

 for non-prothrombic factors whose homeostatic level also seems to depend 

 on vitamin K, for molecular data and plasma concentrations are unknown. 

 The preparation of menadione with C^'^Hs in the 2 position, or C^* in either 

 of the rings, has been described;'* preliminary biologic studies with such 

 preparations have been reported.'® 



What enzymes or types of enzyme are involved in the vitamin K reaction 

 is by no means clear. A variety of isolated experiments has been performed 

 in which naphthoquinones with vitamin K activity have had a stimulating 

 or inhibitory effect; in most cases the evidence is not clear whether the 

 phenomena are actually vitamin K-specific or are a general property of 

 naphthoquinones. Enzyme systems reported to be inhibited by 1,4-naph- 

 thoquinones include heart muscle succinoxidase,'^ choline acetylase,'* and 

 lactic acid-producing bacterial enzymes.'^ The configuration of menadione 

 and phytyl menadione is theoretically and actually adequate for Stecker 

 degradation of a-amino acids. *° 



McCawley and Gurchot^^ reported that the redox potential of vitamin K 

 is characteristic of those substances inhibiting catheptic proteolysis. They 



2« R. N. Lyons, Nature 155, 633 (1945) . 



21 H. Dam, J. Glavind, L. Lewis, and E. Tage-Hansen, Skand. Arch. Physiol. 79, 

 Suppl. 121 (1938). 



22 A. J. Quick, The Physiology and Pathology of Hemostasis. Lea and Febiger, 

 Philadelphia, 1951. 



23 W. H. Seegers and A. G. Ware, Federation Proc. 7, 186 (1948). 



2^ W. H. Seegers, E. C. Loomis, and J. M. Vandenbelt, Proc. Soc. Exptl. Biol. Med. 



56, 70 (1944). 

 26 P. P. T. Sah, Z. Vitaminforsch. 3, 40 (1949-1950) ; C. J. Collins, J. Am. Chem. Soc. 



73, 1038 (1951); A. Murray and A. R. Ronzio, ibid. 74, 2408 (1952); R. V. Phillips, 



L. W. Trevoy, L. B. Jaques, and J. W. T. Spinks, Can. J. Chem. 30, 844 (1952). 

 26 P. F. Solvonuk, L. B. Jaques, J. E. Leddy, L. W. Trevoy, and J. W. T. Spinks, 



Proc. Soc. Exptl. Biol. Med. 79, 597 (1952). 

 " E. G. Ball, C. B. Anfinsen, and O. Cooper, /. Biol. Chem. 168, 257 (1947). 

 28 C. Torda and H. G. Wolff, Proc. Soc. Exptl. Biol. Med. 57, 236 (1944); C. Torda 



and H. G. Wolff, Science [N. S.] 103, 645 (1946). 

 23 W. D. Armstrong, W. W. Spink, and J. Kahnke, Proc. Soc. Exptl. Biol. Med. 53, 



230 (1943); P. Atkins and J. L. Ward, Brit. J. Exptl. Pathol. 26, 120 (1945). 

 3" A. Sch0nberg, R. Moubasher, and A. Said, Nature 164, 140 (1949). 

 " E. L. McCawley and C. Gurchot, Univ. California Pubis. Pharmacol. 1, 325 (1940). 



