Developing ICP-MS/MS for the detection and determination of synthetic DNA-protein crosslink models via phosphorus and sulfur detection

Abstract

Various endogenous and exogenous agents drive the un-directed formation of covalent bonds between proteins and DNA. These complex molecules are of great biological relevance, as can derive in mutations, but are difficult to study because of their heterogeneous chemical properties. New analytical approaches with sufficient detection capabilities to detect and quantify these compounds can help to standardize study models based on synthesized standards. The use of atomic spectrometry can provide quantitative information on the DNA-protein cross-link reaction yield along with basic stoichiometry of the products, based on internal elemental tags, sulfur from Cys and Met amino acids, and phosphorus from the DNA. A new instrumental approach to remove isobaric and polyatomic interferences from ³¹P⁺ and ³²S⁺ was developed recently, with state-of-the-art for interference removal that captures ³¹P⁺ in Q1; it reacts with O₂ in an octopole collision-reaction cell generating ⁴⁷PO⁺, therefore allowing detection in Q3 without ³¹NOH⁺/⁴⁸Ca/⁴⁷Ti interferences. Similarly, ³²S⁺ is reacted to ⁴⁸SO⁺, eliminating the polyatomic interferences at m/z = 32. In conjunction with the high resolving power of high-performance liquid chromatography (HPLC), this newer technology was applied by to the product purification of a DNA-protein cross link model and some preliminary structural studies.