Mass spectrometric encoding

Fitch et al. has recently published a new cation-exchange LC/MS method for decoding dialkylamine-encoded combinatorial libraries without the necessity to derivatise [35] and using a new tag set designed to contain unique masses for each code. We have concentrated on the development of new chromatographic and mass spectrometric methods that utilise the rapid dansyl derivatisation to improve specificity as well as chromatographic reproducibility and resolution. 

Chemical encoding strategies rely on the assumption that the chemical analysis of a given member of the library is more difficult than the analysis of a chemical tag. In most cases this assumption is valid and justifies the described technique. Some libraries have been prepared and characterized by individual mass spectrometric analysis of each member of the library. However, to obtain unambiguous results, the following criteria must be fulfilled ... 

The human T-cell leukemia virus type 1 (HTLV-1) causes adult T-cell leukemia (ATE) and HTLV-l-associated myelopathy/tropical spastic paraparesis (HAM/ TSP) [69]. HTLV-1 encodes a transactivator. Tax, that is critical for virus replication and plays a central role in the development of ATL and HAM/TSP [69]. Tax does not bind to DNA directly but functions by interacting with a variety of cellular proteins [69]. Many protein-protein interactions of Tax have been determined by mutational analysis including CREB [70-72] and NF-kB [70,72]. To identify all the cellular proteins that interact with Tax, Wu et al. used chromatography, 2D gel electrophoresis, and mass spectrometric analysis of an HTLV-1-infected cell line (C81) [73]. As Tax functions in both the cytoplasm and the nucleus [70,74], Tax-interacting proteins were identified from both cellular compartments. Some of the cytoplasmic proteins included small GTPases and components of the cytoskeleton while some of the more interesting nuclear proteins included components of the SWl/SNF chromatin remodeling complex [73]. 

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