Methionine Content of the Animal and Plant Organism 577 



CONCLUSIONS 



1. The mean contents of methionine, cysteine and cystine in the serum, and 

 of oxidized glutathione in the blood of rats changes with age. In old rats the 

 methionine content is lower and that of cystine and oxidized glutathione is 

 higher than in yotmg ones. 



2. Intramuscular administration of cysteine (50 mg/kg of body weight for 16 

 days) to old animals (rats, guinea pigs and dogs) leads to a considerable increase in 

 the methionine content. It may be supposed that the increase in the methionine 

 content after the administration of cysteine to old animals is a very profound 

 biological process which may be associated with the age of the animal. 



3. The addition of methionine or cysteine to the nutrient medium on which 

 the mould Aspergillus niger, which contains no methionine, is cultivated, leads 

 to the appearance of methionine in the composition of the mould as shown by 

 chromatography. 



4. The evidence obtained suggests that it would be worth studying the con- 

 version of the sulphur-containing amino acids into one another in the onto- 

 genesis and phylogenesis of organisms in relation to the physiological state of 

 the animal and the conditions of its existence. 



REFERENCES 



1. A. E. Braunshteïn, Biokhimiya aminokislotnogo obmena, Izd. med. Akad. Nauk 



S.S.S.R., Moscow, 1949. 



2. H. R. V. Arnstein & J. C. Crawhall, Biochem.J., 55, 280, 1953. 



3. R. Brdicka, Coll. Czech, chem. Commun. 1953 (3) 148. 



4. R. Brdicka, Research, Land., i, 25, 1947. 



5. H. M. Dyer & V. du Vigneaud, J. biol. Chem., 109, 477, 1953. 



6. V. du Vigneaud, G. W. Klimmer, J. R. Rachel & M. Kahn, J. biol. Chem., 155, 



645, 1944. 



7. V. du Vigneaud, H. M. Dyer & J. Harmon, J. biol. Chem., loi, 719, 1933. 



8. W. C. Hess & M. X. Sullivan, J. biol. Chem., 151, 635, 1943. 



9. N. H. Horowitz, J. biol. Chem., 171, 225, 1947; Fed. Proc, 6, 262, 1947. 



10. A. A. Close & H. J. Almquist, J', biol. Chem., 138, 407, 1941. 



11. L. J. Machlin, L. S. Struglia & P. B. Pearson, Arch. Biochem. Biophys., 59, 326, 



1955- 



12. C. I. Parhon, S. Oeriu & I. Tanase, Bui. sti. (Sec. St. Med.) Acad. Repub. rom., 



1, {3), 884, 1955- 



13. C. I. Parhon, S. Oeriu & I. Tanase, Bui. sti. (Sec. St. Med.) Acad. Repub. row., 7, (3), 



891, 1955. 



14. W. C. Rose et al., J. biol. Chem., 114, Ixxxv, 1936. 



15. W. C. Rose & R. L. Wixon, J. biol. Chem., 215, 763, 1955. 



16. J. A. Sterol & J. A. Weiss, Fed. Proc, 14, 287, 1955. 



17. Shiota Tetsua & F. M. Clark, J. Bact., 70, 339, 1955. 



18. E. Tropp, Klin. Wschr., p. 405, 1938. 



19. B. Wassel, J. biol. Chem., 140, 323, 1941. 



20. A. White & E. F. Beach, J. biol. Chem., 122, 210, 1938. 



21. M. WOMACK, K. S. Kemmrer & W. C. Rose, J. biol. Chem., 121, 403, 1937. 



22. J. Wood & H. R. Gutman, J. biol. Chem., 179, 535, 1949. 



23. G. E. Woodward & E. S. Fry, J. biol. Chem., 97, 465, 1932. 



37 



