BIOCHEMICALLY IMPORTANT COMPOUNDS KJl 



particularly to substances which are o£ importance for life, 

 such as the amino acids, proteins, carbohydrates, certain 

 lipids, etc. 



This capacity of protoplasm to form and store only one 

 antipode of dissymmetric molecules is an indication of the 

 asymmetry of living substance. It is absent from non-living 

 nature but is a characteristic feature of all living things. ^'^^ 

 The fact was noticed by L. Pasteur^*^ who wrote of it as 

 " this great character which establishes perhaps the only well 

 marked line of demarcation that can, at present, be drawn 

 bet^veen the chemistry of dead matter and the chemistry of 

 living matter ". The same idea was later emphasised by V. 

 Vernadskir*^ who thought that the chemical non-identity of 

 the dextro and laevo forms ^vithin living bodies was due to 

 the presence of a peculiar ' configuration of cosmic space ' 

 in these bodies which cannot be reproduced under laboratory 

 conditions. However, a large body of evidence has since 

 been obtained, which shows conclusively that dissymmetry 

 can arise independently of life.^^" 



Pasteur himself^" had already pointed out the ways in 

 which the formation of dissymmetric substances might have 

 been achieved in nature. In his opinion this could occur 

 in the presence of some other dissymmetric substance or as 

 a result of the action of some asymmetric physical factor. 

 The first part of this hypothesis w^as later developed by E. 

 Fischer^^^ in its application to the synthesis of the higher 

 sugars. In increasing the number of carbon atoms in a sugar 

 molecule by the cyanhydrin synthesis, E. Fischer showed that 

 the presence of a particular configuration in the original 

 molecule of sugar affects the form of the derivative, and. of 

 the two possible configurations which could result from the 

 entry of the new carbon atom into the compound, only one 

 actually arises. Fischer put forward the hypothesis that the 

 dissymmetry of carbohydrates and other substances in living 

 cells arises because they are synthesised within organisms 

 under the influence of optically active substances such as 

 chlorophyll. 



W. Marckwald^^^ confirmed this hypothesis experimentally. 

 He obtained an optically active (dissymmetric) substance by 

 using in its synthesis a substance which is already dissymmct- 



