CHARACTERIZATION OF S-ADENOSYL-L-METHIONINE-CONSUMING ENZYMES WITH 1-STEP EZ-MTASE: A UNIVERSAL COUPLED-ASSAY

1 . A method of measuring activity of a methyltransferase, comprising contacting the methyltransferase with S-adenosyl-L-methionine (SAM) and/or a fluorescent SAM analog to generate S-adenosyl-L-homocysteine (SAH), quantitatively catabolizing the SAH to S-inosyl-L-homocysteine (SIH) in the presence of deaminase TM0936, and measuring the SIH produced.

2 . The method of claim 1 , wherein the methyltransferase is a protein methyltransferase, a DNA methyltransferase or an RNA methyltransferase.

3 . The method of claim 1 , wherein the methyltransferase is a lysine methyltransferase, an arginine methyltransferase, a histone-lysine N-methyltransferase, a glycine N-methyltransferase or a sarcosine/dimethylglycine N-methyltransferase.

4 . The method of claim 1 , wherein the method is carried out at a pH between pH 5 and pH 10.

5 . The method of claim 1 , wherein the method is carried out in the presence of sinefungin.

6 . The method of claim 1 , wherein the methyltransferase activity is quantified by measuring a decrease of absorbance at 263 nm.

7 . The method of claim 1 , wherein the SAM is a fluorescent SAM analog.

8 . The method of claim 7 , wherein the fluorescent SAM analog is S-8-aza-adenosine-L-methionine (8-aza-SAM), and wherein the methyltransferase activity is quantified by measuring a decrease of fluorescence emission at 360 nm.

9 . The method of claim 1 , wherein the methyltransferase activity is measured from or within a biological sample.

10 . A method of screening for an inhibitor of a methyltransferase, comprising carrying out the method of claim 1 in the presence and in the absence of a candidate compound, wherein a decrease in the activity of methyltransferase in the presence of the candidate compound, compared to methyltransferase activity in the absence of the candidate compound, indicates that the candidate compound is an inhibitor of the methyltransferase.

11 . A kit for measuring the activity of a methyltransferase or a radical SAM enzyme, the kit comprising:

S-adenosyl-L-methionine (SAM) and/or fluorescent SAM analog; and

deaminase TM0936.

12 . The kit of claim 11 , wherein the fluorescent SAM analog is S-8-aza-adenosine-L-methionine (8-aza-SAM).

13 . A method of measuring activity of a radical SAM enzyme, comprising contacting the radical SAM enzyme with S-adenosyl-L-methionine (SAM) to generate 5′-deoxyadenosine (5DOA), quantitatively catabolizing 5DOA to 5′-deoxyinosine (5DOI) in the presence of the deaminase PA3170, and measuring the 5DOI produced.

14 . The method of claim 13 , wherein the method is carried out at a pH between pH 5 and pH 10.

15 . The method of claim 13 , wherein the reaction is carried out in the presence of sinefungin.

16 . The method of claim 13 , wherein the radical SAM enzyme activity is quantified by measuring a decrease of absorbance at 263 nm.

17 . The method of claim 13 , wherein the radical SAM enzyme activity is measured from or within a biological sample.

18 . A method of screening for an inhibitor of a radical SAM enzyme, comprising carrying out the method of claim 13 in the presence and in the absence of a candidate compound, wherein a decrease in the activity of radical SAM enzyme in the presence of the candidate compound, compared to radical SAM enzyme activity in the absence of the candidate compound, indicates that the candidate compound is an inhibitor of the radical SAM enzyme.

19 . A kit for measuring the activity of a radical SAM enzyme, the kit comprising:

S-adenosyl-L-methionine (SAM) and

deaminase PA3170.

20 . The method of claim 1 , wherein the contacting and catabolizing are done as a one-step method.

21 . The method of claim 20 , wherein the method is a high throughput screening method.