220 



acids are, in both enantiomorphous configurations, decomposed by it 

 with very differing .velocities ; the differences in velocity can amount to 

 50% and 1 30% of the values observed in the case of the other antipode. 



Herzog and Meier 1 ) stated that mould-cultures, after being 

 killed by means of acetone or methyl-alcohol, will oxidize dextro- 

 gyratory tartaric acid much more rapidly than the laevogyratory 

 isomeride, and the same appeared to be the case with other oxy- 

 acids, although not to so high a degree. A similar difference in velocity 

 of attack was found by Abderhalden and Pringsheim 2 ) if the 

 juice of squeezed-out cells of Aspergillus Wentii, or of Allenheria 

 Gayoni were used for the decomposition of polypeptides , like leucyl- 

 glycine into their optically active forms. After this,, it can hardly 

 be doubted any longer that of the "specific" attack of living organisms 

 or of enzymes, a common explanation can as a matter of fact be given, 

 and that this must be considered to consist in the differences in 

 velocity of attack only. 



Most of these reactions appear intrinsically to be true reversible 

 or semi-reversible reactions 3 ): thus glycose is changed by maltase 

 into maltose (or rather into iso-maltose) 4 ) in this way; kefir-lactase 

 acting on a mixture of glycose and galactose, produces iso-lactose, etc. 

 The same is true for the action of lipase, of emulsine, and of a 

 number of other animal or vegetable enzymes. 



The close analogy with the effect of yeasts on sugars, formerly 

 stated by Fischer 5 ), is evident; thus from i-glycose the /e/flianded 

 component may for instance be obtained by means of yeast, because 

 yeast attacks the d-glucose, while it does not attack the l-glycose, 

 or only to an unappreciable extent, during the same time ; in the 

 same way as in Pasteur's original experiments the d-ammonium- 

 iartrate was attacked almost exclusively by Penicillium glaucum 



1) R. O. Herzog and A. Meier, Zeits. f. physiol. Chem. 59. 57. (1909). 



2) E. Abderhalden and H. Pringsheim, Zeits. f. physiol. Chem. 59.249. 

 (1909); cf. also: G. Bredig and K. Fajans, Ber. d.d. Chem. Ges. 41. 752. (1908). 



3) Literature on the reversibility of enzyme-action ; A. Croft Hill, Journ. Chem. 

 Soc. London, 73. 634. (1898) ; 83. 578. (1903) ; J. H. Kastle and A. S. Loevenhart, 

 Amer. Chem. Journal 24. 491. (1900); M. Hanriot, Compt. rend, de 1'Acad. d. 

 Sc. Paris 132. 212. (1901); H. Pottevin, Compt. rend. 136. 767. (1903); E. Bour- 

 quelot and M. Bridel, Ann. de Chim. et Phys. 28. 145. (1913); W. M. Bayliss, 

 Journ. Physiol. 36. 221. (1907); 43. 455. (1912); 46. 236. (1913). 



4) E. Fischer, Ber. d.d. Chem. Ges. 32. 3617. (1899); Zeits. f. physiol. Chemie. 

 26. 60. (1898); E. Fischer and E. F. Armstrong, Ber. d.d. Chem. Ges. 35. 3144. 

 (1902). 



5) E. Fischer, Ber. d.d. Chem. Ges. 23. 2620. (1890). 



