Beard, On the Occurrence of Dextro-rotatory Albumins in Organic Nature. |f),"> 



citation is taken: "That micro-organisms generally of two optically 

 isomeric compounds prefer the one has long been known from the 

 investigations of Pasteur and others; but with the yeasts and the 

 sorts of sugars the matter lies somewhat differently, since here it 

 is not alone a question of the antithesis of two optical antipodes, 

 but out of a great number of geometrical forms some only satisfy 

 the needs of the cell. It may be anticipated, that the same obser- 

 vation will be found in other micro-organisms, and, moreover, in 

 other groups of organic substances, and perhaps very many chemical 

 processes, which happen in the organism, are influenced by the 

 geometry of the molecule. Under these circumstances it is worth 

 while to seek after the reason of the phenomenon, and it lies on 

 the surface, that the explanation is first of all to be sought in the 

 region of stereochemistry. 



Among the agents, which the living cell makes use of, the 

 different albuminous substances play the chief role. They are also 

 optically active, and since they arise synthetically from the carbo- 

 hydrates of plants, one may, indeed, conclude, that the geometrical 

 build of their molecule, in respect of asymmetry, is in essentials 

 similar to that of the natural hexoses. Under this conclusion it 

 is not difficult to understand, that the yeast-cell with its asym- 

 metrically formed agent can only attack, and force into 

 fermentation, the sorts of sugars the geometry of which 

 departs not too far from that of grape-sugar 2 )." 



The second memoir bears the date Oct. 29, 1894, and in it, 

 under the title "The Influence of the Configuration upon the action 

 of the Enzymes" the author, Prof. Emil Fischer, set up the 

 simile of "lock & key" in the course of the following discussion 

 (on p. 2992 299B): "But the observations suffice already to approve 

 (the principle) that with respect to the configuration of their objects 

 of attack the enzymes are just as elective as the yeasts and other 

 micro-organisms. In this respect the analogy of both phenomena 

 appears so complete that one may adopt the same reason for it, 

 and with this I return to the hypothesis of Thierfelder and 

 myself, already referred to. As is well known, invertin and 

 emulsin have many resemblances to the proteid stuffs, and like 

 these they possess an asymmetrically built-up molecule. Their 

 restricted action upon the glucosides would permit of explanation 

 by the supposition, that only with similar geometrical build can 

 that approach of the molecule take place, which is requisite for 

 the resolution of the chemical process. To use a simile, I should 

 like to say, that enzyme and glucoside must fit each other like 



2) Fischer, Emil und Thierfelder, Hans. ,,Verhalten der verschiedenen 

 Zucker gegen reine Hefen", in: Ber. d. d. chem. Ges. ; V. 21, p. 20312037, 1894. 



