Patent ID: 7910059

Claim:
A kit comprising an active ester compound that is a 6 or 7 membered heterocyclic ring comprising a ring nitrogen atom that is N-alkylated with a substituted or unsubstituted acetic acid moiety to which the alcohol moiety of the active ester is linked through the carbonyl carbon of the N-alkyl acetic acid moiety, wherein the compound is isotopically enriched with one or more heavy atom isotopes and further comprising one or more reagents, containers, enzymes, buffers or instructions; wherein the compound has the formula: wherein; a) RG is a reactive group that is an electrophile; b) Z is O, S, NH or NR 1 ; c) each J is the same or different and is selected from the group consisting of: H, deuterium (D), R 1 , OR 1 , SR 1 , NHR 1 , N(R 1 ) 2 , fluorine, chlorine, bromine and iodine; d) W is an atom or group that is located ortho, meta or para to the ring nitrogen and is selected from the group consisting of: NH, N—R 2 , P—R 2 , O or S; and e) each carbon of the heterocyclic ring has the formula CJ 2 ; f) each R 1 is the same or different and is an alkyl group comprising one to eight carbon atoms which may optionally contain a heteroatom or a substituted or unsubstituted aryl group wherein the carbon atoms of the alkyl and aryl groups independently comprise linked hydrogen deuterium and/or fluorine atoms; and g) R 2 is an amino alkyl, hydroxy alkyl, thio alkyl group or a cleavable linker that cleavably links the reagent to a solid support wherein the amino alkyl, hydroxy alkyl or thio alkyl group comprises one to eight carbon atoms, which may optionally contain a heteroatom or a substituted or unsubstituted aryl group, and wherein the carbon atoms of the alkyl and aryl groups independently comprise linked hydrogen, deuterium and/or fluorine atoms.