A modified nucleotide, intended for the enzymatic synthesis of nucleic acids, comprising a "natural" nitrogenous base, a ribose or deoxyribose carbohydrate, and at least one phosphate group, characterized in that it comprises at least one R group, called modifier group, borne by said natural nitrogenous base, R comprising at least one functional end group, said nucleotide being in the form of below: in which: PPPO represents a triphosphate group, describes the possibility of a ribose or deoxyribose molecule, T is a hydrogen, or a cleavable radical chosen from -NH 2, -N 3, - (C=O)H, -C n H 2n+1 with n between 1 and 30, preferably between 1 and 12, -trimethylsilyl, -phosphate, -SO 3, -(C=O)OC n H 2n+1 with n between 1 and 30, preferably between 1 and 12, -(C=O)SC n H 2n+1 with n between 1 and 30, preferably between 1 and 12, -nitrobenzene, -benzyl, -halobenzyl, -amide, -carbonate, -benzoyl, -peroxyl, - nitrile, -thiol, -imide, -carbamate, -cyanate, -alkyne, - phenyl, -halophenyl, -picolyl, M is a group covalently bonded to Q and to Z, M being chosen from alkyl, alkenyl, alkyne, aryl, alkylaryl, heteroaryl, acyl, alkyloxy, alkylamino, alkoxyamino, amido, alkylimido, alkenylimido, arylimido, fluoroalkyl, alkylphosphate, alkylthio, thioacyl, alkylsulfonyl, arylsulfonyl, alkylsulfinyl, alkylammonium, alkylsulfonium, alkylsilyl, alkylcarbonyl, alkylcarbonyl, alkylcarbanyl, alkylcarbamoyl or alkylhydroxylamino, Z is a cleavable group, chosen from -O-, -S-, =SH-, =S=, ≡S-, - SiH 2 -, =SiH-, =Si=, ≡Si-, -Se-, =SeH-, ≡Se-, =Se=, -SeH 2 -, -PH-, =P-, =PH=, ≡P=, ≡PH-, -PH 3 -, -AsH-, =As-, =AsH=, ≡As=, ≡AsH-, -ASH 3 -, amine, ester, silyl, alkyl, benzyl, nitrobenzyl, amide, carbonate, benzoyl, peroxyl, nitrile, thiol, imide, carbamate, cyanate, hydroxylamine, sulfoxide, sulfonate, thiosulfinate, thioester, acyl halide, hypoiodyl, alkyne, halophenyl, halobenzyl, picoyl, diol or disulfide, or chosen from -CH 2 or - NH- when M is a -nitrobenzyl-, a -nitrotolyl-, a -nitroxylyl-, a -nitronaphthyl- or a -nitrophenyl-, Q is a functional, or effector, end group of the R group, Q being chosen from biotin, a protein, a polynucleotide of defined sequence, a carbohydrate, an antigen, a hormone, a neurotransmitter, a glycoside such as digoxin, a sulfur-containing radical, or a bidentate ligand such as catechol, "base" represents a "natural" nitrogenous base chosen from adenine, thymine, cytosine, guanine or uracil, the modifier group R borne by the nitrogenous base forms one of the structures below: in which: "Sugar" represents the bond between the nitrogenous base and the ribose or deoxyribose molecule of the nucleotide molecule, Z 1 and Z 2 are identical or different cleavable group Z. X 1 and X 2, which may be identical or different, represent nitrogen, oxygen or sulfur atoms borne by M and capable of forming, with said nitrogenous bases of the modified nucleotide, intermolecular hydrogen bonds (similar to those observed during conventional pairings between complementary nucleotides). PPPO represents a triphosphate group, describes the possibility of a ribose or deoxyribose molecule, T is a hydrogen, or a cleavable radical chosen from -NH 2, -N 3, - (C=O)H, -C n H 2n+1 with n between 1 and 30, preferably between 1 and 12, -trimethylsilyl, -phosphate, -SO 3, -(C=O)OC n H 2n+1 with n between 1 and 30, preferably between 1 and 12, -(C=O)SC n H 2n+1 with n between 1 and 30, preferably between 1 and 12, -nitrobenzene, -benzyl, -halobenzyl, -amide, -carbonate, -benzoyl, -peroxyl, - nitrile, -thiol, -imide, -carbamate, -cyanate, -alkyne, - phenyl, -halophenyl, -picolyl, M is a group covalently bonded to Q and to Z, M being chosen from alkyl, alkenyl, alkyne, aryl, alkylaryl, heteroaryl, acyl, alkyloxy, alkylamino, alkoxyamino, amido, alkylimido, alkenylimido, arylimido, fluoroalkyl, alkylphosphate, alkylthio, thioacyl, alkylsulfonyl, arylsulfonyl, alkylsulfinyl, alkylammonium, alkylsulfonium, alkylsilyl, alkylcarbonyl, alkylcarbonyl, alkylcarbanyl, alkylcarbamoyl or alkylhydroxylamino, Z is a cleavable group, chosen from -O-, -S-, =SH-, =S=, ≡S-, - SiH 2 -, =SiH-, =Si=, ≡Si-, -Se-, =SeH-, ≡Se-, =Se=, -SeH 2 -, -PH-, =P-, =PH=, ≡P=, ≡PH-, -PH 3 -, -AsH-, =As-, =AsH=, ≡As=, ≡AsH-, -ASH 3 -, amine, ester, silyl, alkyl, benzyl, nitrobenzyl, amide, carbonate, benzoyl, peroxyl, nitrile, thiol, imide, carbamate, cyanate, hydroxylamine, sulfoxide, sulfonate, thiosulfinate, thioester, acyl halide, hypoiodyl, alkyne, halophenyl, halobenzyl, picoyl, diol or disulfide, or chosen from -CH 2 or - NH- when M is a -nitrobenzyl-, a -nitrotolyl-, a -nitroxylyl-, a -nitronaphthyl- or a -nitrophenyl-, Q is a functional, or effector, end group of the R group, Q being chosen from biotin, a protein, a polynucleotide of defined sequence, a carbohydrate, an antigen, a hormone, a neurotransmitter, a glycoside such as digoxin, a sulfur-containing radical, or a bidentate ligand such as catechol, "base" represents a "natural" nitrogenous base chosen from adenine, thymine, cytosine, guanine or uracil, the modifier group R borne by the nitrogenous base forms one of the structures below: in which: "Sugar" represents the bond between the nitrogenous base and the ribose or deoxyribose molecule of the nucleotide molecule, Z 1 and Z 2 are identical or different cleavable group Z. X 1 and X 2, which may be identical or different, represent nitrogen, oxygen or sulfur atoms borne by M and capable of forming, with said nitrogenous bases of the modified nucleotide, intermolecular hydrogen bonds (similar to those observed during conventional pairings between complementary nucleotides).