24 DYNAMICS OF LIVING MATTER 



S- Concerning the Theory of Enzyme Action 



a. Stereochemical Attempts. 



Liebig expressed the idea that ferments or catalytic substances, 

 in general, were bodies in a process of decomposition, and that their 

 condition of motion was communicated to the fermentable body. 

 Schoenbein, Pasteur, and Traube showed the untenability of this view 

 by pointing out that platinum or the yeast cell cannot be well considered 

 as bodies in a condition of rapid decomposition. To-day we do not 

 value it so highly if an author tries to explain phenomena by vague 

 statements concerning the vibration of atoms. Now and then an author 

 still makes the statement that "life is motion," but as Driesch has 

 pointed out, this statement is about as valuable as the information that 

 the philosopher Kant was a vertebrate. 



Certain observations by Pasteur and Emil Fischer seemed, for a 

 time at least, to arouse the hope that the theory of enzymatic action 

 might be found in the field of stereochemistry. Pasteur had observed 

 in the beginning of his scientific career that while the right-handed 

 tartaric acid is easily decomposed by fermentation, the same was not 

 true for left-handed tartaric acid. Pasteur assumed that the geometri- 

 cal shape of the tartaric acid molecules exercises an influence upon the 

 fermentability of their solution. From the point of view of stereo- 

 chemistry the forms of the right- and left-handed tartaric acid molecules 

 show the same relation of symmetry as our right and left hand, or some 

 asymmetrical object and its mirror image. It appears from Pasteur's 

 biography that he expected important discoveries to be made concern- 

 ing the nature of life from this relation between the form of the asym- 

 metrical molecules and their biological effect. Pasteur's discovery 

 found httle consideration until it was taken up by E. Fischer.* He 

 found that the alcohoHc fermentation through yeast, e.g. Saccharomyces 

 cerevisicB, depends upon the molecular constitution and configuration 

 of the various sugars. Saccharomyces cerevisice brings about an 

 alcoholic fermentation only with triose and hexose, possibly also with 

 nonose. Tetrose, pentose, heptose, and octose undergo no alcoholic 

 fermentation with this form of yeast. It is evident that only those 

 monosaccharides are fermentable by yeast which have three or a 

 multiple of three atoms of carbon in the molecule. As far as the influ- 

 ence of the stereochemical configuration of the sugars and glucosides 

 upon their fermentabiUty is concerned, a similar relation as that found 

 by Pasteur exists. Of the hexoses or hexaldoses there exist sixteen 



* E. Fischer und Thierfelder, Berichte der deutsch. chem. Gesellsch., Vol. 27, pp. 2036 and 

 2985, 1894. Fischer, Zeitsch. fur physiplog. Chemie, Vol. 26, p. 60, 1898. 



