Functional molecule, functional molecule synthesizing amidite and target substance analysis method

Abstract

To provide a functional molecule including a modified nucleotide unit having a substituent introduced to a base thereof, wherein the substituent is removably introduced to the base; a functional molecule synthesizing amidite that has a substituent removably introduced to its base and that is used for the manufacture of the functional molecule; and a target substance analysis method including: preparing a random pool of functional molecules using a functional molecule synthesizing amidite; screening a functional molecule having affinity for a target substance from the random pool; amplifying the functional molecules having affinity for the target substance, wherein the method further comprises, prior to the amplification step, removing a substituent from the functional molecule having affinity for the target substance.

What is claimed is: 
     
         1 . A target substance analysis method comprising:
 preparing a random pool of functional nucleic acid molecules having substituents attached to the nucleic acid bases using a functional molecule synthesizing amidite;   screening a functional molecule having affinity for a target substance from the random pool;   removing the substituent from the functional molecule; and   amplifying the functional molecules having affinity for the target substance.   
     
     
         2 . The method according to  claim 1  wherein the amidite is expressed by General Formula (I) below, wherein substituent Y is removably introduced to base X: 
       
         
           
           
               
               
           
         
         where X represents a base, Y represents a substituent and Q represents one of a hydrogen atom and a hydroxyl group. 
       
     
     
         3 . The method according to  claim 2 , wherein the substituent Y is introduced to the base X through any of an aromatic carboxylic acid structure and an aliphatic carboxylic acid structure in the substituent Y. 
     
     
         4 . The method according to  claim 2 , wherein the substituent Y is introduced to the base X through an aromatic carboxylic acid structure in the substituent Y, and the base X is one of adenine and cytosine. 
     
     
         5 . The method according to  claim 2 , wherein the substituent Y is introduced to the base X through an aliphatic carboxylic acid structure in the substituent Y, and the base X is guanine. 
     
     
         6 . The method according to  claim 1  wherein the substituent can be removed by ammonia treatment. 
     
     
         7 . The method according to  claim 1  wherein the substituent can be removed by ammonia treatment but cannot be removed by DBU treatment in acetonitrile. 
     
     
         8 . The method according to  claim 1  wherein the amidite is expressed by General Formula (II) below in which the substituent Y is additionally protected by a protection group Z: 
       
         
           
           
               
               
           
         
         where X represents a base, Y represents a substituent, Z represents a protection group and Q represents one of a hydrogen atom and hydroxyl group. 
       
     
     
         9 . The method according to  claim 8 , wherein the protection group Z can be removed under conditions where the substituent Y is not removed. 
     
     
         10 . The method according to  claim 9  wherein the protection group Z can be removed by DBU treatment in acetonitrile. 
     
     
         11 . The method according to  claim 1  wherein the functional molecule comprises two or more different modified nucleotide units having different substituents.