Novel nucleic acid base pair

Abstract

A novel artificial nucleic acid base pair which is obtained by forming a selective base pair by introducing a group having steric hindrance (preferably a group having steric hindrance and static repulsion and a stacking effect) and can be recognized by a polymerase such as DNA polymerase; a novel artificial gene; and a method of designing nucleic acid bases so as to form a selective base pair with the use of steric hindrance, static repulsion and stacking effect at the base moiety of the nucleic acid. An artificial nucleic acid comprising these bases; a process for producing the same; a codon containing the same; a nucleic acid molecule containing the same; a process for producing a non-natural gene by using the same; a process for producing a novel protein by using the above nucleic acid molecule or non-natural gene, and the like.

1 .- 26 . (canceled) 
     
     
         27 . A codon comprising one or more nucleic acid comprising a structure to hinder base pair formation with a natural nucleic acid due to stearic hindrance and electrostatic repulsion, without decreasing base stacking. 
     
     
         28 .- 40 . (canceled) 
     
     
         41 . A codon according to  claim 27 , wherein the nucleic acid base comprises a purine derivative having a group at position-6 which can generate stearic hindrance. 
     
     
         42 . The codon according to  claim 27 , wherein the nucleic acid base is 2-amino-6-N,N-dimethylamino-purine. 
     
     
         43 . The codon according to  claim 27 , wherein the nucleic acid base is 2-amino-6-thienyl-purine or derivatives thereof. 
     
     
         44 . The codon according to  claim 27 , wherein the nucleic acid has base containing pyridine having hydroxyl group or keto group at position-2. 
     
     
         45 . The codon according to  claim 27 , wherein the nucleic acid base is pyridine-2-one or tautomer thereof. 
     
     
         46 . The codon according to  claim 27 , wherein the nucleic acid is a nucleic acid constructing base pair with its complementary nucleic acid. 
     
     
         47 . The codon according to  claim 27 , wherein the codon encodes an amino acid. 
     
     
         48 . The codon according to  claim 47 , wherein the amino acid comprises a non-natural amino acid. 
     
     
         49 . A nucleic acid molecule comprising nucleic acid comprising a structure to hinder base pair formation with a natural nucleic acid due to stearic hindrance and electrostatic repulsion, without decreasing base stacking. 
     
     
         50 . The nucleic acid molecule according to  claim 49  wherein the nucleic acid molecule has whole or part of genetic information of the natural gene. 
     
     
         51 . A process for production of nucleic acid having complementary strand thereof comprising reacting the polymerase with the nucleic acid molecule comprising a structure to hinder base pair formation with a natural nucleic acid due to stearic hindrance and electrostatic repulsion, without decreasing base stacking. 
     
     
         52 . The process according to  claim 51  wherein the polymerase is DNA polymerase or RNA polymerase. 
     
     
         53 . A process for production of non-natural nucleic acid comprising inserting or substituting one or more nucleic acid comprising a structure to hinder base pair formation with a natural nucleic acid due to stearic hindrance and electrostatic repulsion, without decreasing base stacking. 
     
     
         54 . The process for production of non-natural nucleic acid according to  claim 51  wherein a position, to which the nucleic acid comprising a structure to hinder base pair formation with a natural nucleic acid due to stearic hindrance and electrostatic repulsion without decreasing base stacking is inserted or substituted; and has a codon unit portion and has a base sequence portion encoding natural amino acid sequence. 
     
     
         55 . A process for production of protein having amino acid sequence based on codons of the nucleic acid according to  claim 49  or the non-natural nucleic acid obtained by the method according to  claim 53 . 
     
     
         56 . The process for production of protein according to  claim 55  comprising being inserted or substituted by the non-natural amino acid in the part or whole of amino acid sequence of natural protein. 
     
     
         57 . A microorganism which is transformed by non-natural gene which can be produced by the process according to  claim 53 . 
     
     
         58 . A method for screening functions of amino acids coded by natural gene comprising using the non-natural gene which can be produced by the method according to  claim 53 .