Disclosed are W-position modified cytidine nucleotides of formula (I). Provided herein are methods of chemical synthesis of AP-modified cytidine nucleoside triphosphates and their applications as well as uses of the cytidine analogues for the synthesis of modified nucleic acids. The nucleic acid molecule includes DNA, RNA or a combination of DNA/RNA. One of many applications of modified cytidine nucleotides described herein is enzyme selection, when an enzyme of interest bears an activity of an esterase, amidase, oxidoreductase, lyase, ligase or other enzymatic activity, formula (I) wherein the substituants are as defined in the appended claims.