Synthetic cofactor analogs of S-adenosylmethionine as ligatable probes of biological methylation and methods for their use

A cofactor analog of the Formula I:

• wherein R1 is attached through a nitrogen atom and is selected from the group consisting of
• X is a leaving group selected from the group consisting of I, Br, Cl, F, tosylate (OTs), mesylate (OMs) or triflate (OTf);
• R3 is selected from the group consisting of:
• R2 is independently selected from the group consisting of H, —N3, —NH(CH2)n2N3, —NH(CH2CH2O)n1N3, —NH(CH2)n2C≡CH, —NH(CH2O)n1C≡CH,
• R4 is selected from the group consisting of H, CH3, and triarylphosphine;
• n1 is an integer from 1-10 inclusive and n2 is an integer from 2-10 inclusive;
• and zwitterionic forms and salts thereof;
• provided that when R1 is
• R2 is not N3 or H.

A cofactor analog of the Formula I:

• wherein R1 is selected from the group consisting of
• R2 is selected from the group consisting of H, —N3, —NH(CH2)n1N3, —NH(CH2CH2O)n1N3, —NH(CH2)n2C≡CH, —NH(CH2O)n1C≡CH,
• Su is a substrate selected from the group consisting of a nucleic acid, a polynucleotide, a phospholipid, a peptide, a polypeptide, a peptide nucleic acid and a protein;
• n1 is an integer from 1-10 inclusive and n2 is an integer from 2-10 inclusive, and zwitterionic forms and salts thereof
• provided that when R1 is
• R2 is not N3 or H.