214 ^- R-^CKER VOL. 4 (1950) 



3- io~2 M. Some variation around this value was found with different preparations. This 

 variation might be explained by the presence of two different aspartases reported by 

 Gale^. 



discussion 



Rapid and convenient spectrophotometric methods for the determination of gly- 

 colytic enzymes of the Meyerhof-Embden scheme have been developed by Warburg 

 and his school. These methods have been valuable in following purification and also 

 for kinetic studies of these enzymes. The high absorption coefficients in the ultraviolet 

 of unsaturated compounds such as fumaric and aconitic acid have been made the basis 

 for a method of measuring their enzymatic formation. Other compounds such as crotonic 

 and vinyl-acetic acid were also found to show a high absorption in the ultraviolet. These 

 latter compounds are known to be metabolized by animal tissues and by bacteria and 

 may be intermediates of fatty acid metabolism. In view of their high specific light 

 absorption, their enzymatic formation and breakdown could be followed by spectro- 

 photometric tests similar to those described in this paper. 



The occurrence of unsaturated compounds as intermediates of metabolism of 

 amino acids such as serine and threonine has been postulated^. The probably high 

 absorption in the ultraviolet of such intermediates may help in the elucidation of the 

 pathway of the metabolic breakdown of these amino acids. Advantage has been taken 

 of the high absorption coefficients of reduced coenzymes I and II, keto acids, dehydro- 

 peptides, and am.ino acids, such as tyrosine for enzymatic studies with these compounds. 

 The present study shows that the metabolism of unsaturated organic substances may 

 be followed by 2. similar technique. 



SUMMARY 



A spectrophotometric method of measuring the enzymatic formation and disappearance of 

 umaric and cis-aconitic acids is reported. 



RESUMfi 



Nous decrivons une methode spectrophotometrique qui permet de mesurer la formation et la 

 disparation enzymatique de I'acide fumarique et de I'acide cis-aconitique. 



ZUSAMMENFASSUNG 



Eine spektrophotometrische Methode zur Messung der enzymatischen Bildung und Zferstorung 

 von Fumarsaure und czs-Akonitsaure wird beschrieben. 



REFERENCES 



1 E. Laki and K. Laki, Enzymologia, g (1941) 139. 



2 S. OcHOA AND E. Racker, Unpublished experiments. 



3 E. M. Scott, Arch. Biochem., 18 (1948) 131. 



* H. LiNEWEAVER AND D. BuRK, /. Ar}t. Chem. Soc, 56 (1934) 658. 



'' E. F. Gale, Biochem. J., 32 (1938) 1583. 



^ E. Chargaff and D. B. Sprinson, /. Biol. Chem., 151 (1943) 273. 



Received April 28th, 1949 



