Synthesis of an amino acid analogue to incorporate p-aminobenzyl-EDTA in peptides.

A convenient and straightforward synthesis of an amino acid analog, [p-(N-alpha-Fmoc-L-aspartic acid-beta-amido)benzyl]-EDTA tetra-tert-butyl ester, compatible with Fmoc solid phase peptide synthesis strategy is described. This reagent was used to incorporate p-aminobenzyl-EDTA at an internal sequence position in an HIV-1 Tat protein fragment. After cleavage from the resin and standard deprotection, the peptide was purified by high-performance liquid chromatography and characterized by mass spectrometry. Through this methodology, flexible linkers of different lengths and containing various structures can be placed between the alpha-carbon backbone of peptides and metal chelates. These peptides will provide a new class of affinity cleaving reagents that can be directed against protein and nucleic acid targets.