Methods of quantifying methylglyoxal-induced nucleic acid adducts
Methods of quantifying a N 2 -(1-carboxyethyl)-2′-deoxyguanosine (CEdG) and N 2 -(1-carboxyethyl)-guanosine (CEG) levels in biological samples and comparing those levels to known normal levels can diagnose a number of metabolic disorders or complications associated therewith, including diabetes, its associated complications, and cancer. Methods can also determine whether therapies for disorders are effective by measuring CEdG and CEG levels before and after treatment. Measurement of CEdG and CEG levels is achieved by using liquid chromatography electrospray ionization tandem mass spectrometry.
1. A method of synthesizing an internal standard comprising a stereochemically pure 15 N 5 -(1-carboxyethyl)-guanosine ( 15 N 5 -CEG) (R) and stereochemically pure 15 N 5 -CEG (S), the method comprising:
(i) generating a mixture comprising mixing DL-glyceraldehyde with 15 N 5 -labeled guanosine monophosphate ( 15 N 5 -GMP) and sodium phosphate in water;
(ii) heating the mixture; and
(iii) purifying stereochemically pure 15 N 5 -CEG (R) and stereochemically pure 15 N 5 -CEG (S) from the mixture using high-performance liquid chromatography (HPLC).
2. The method of claim 1 , wherein the 15 N 5 -CEG (R) and 15 N 5 -CEG (S) are further dephosphorylated.