Synthesis of new 2,2,5,5-tetramethyl-2,5-dihydro-1H-pyrrol-1-yloxyl radicals and 2-substituted-2,5,5-trimethylpyrrolidin-1-yloxyl radicals based alpha-amino acids

Abstract

Unnatural paramagnetic alpha-amino acids with 2,2,5,5-tetramethyl-2.5-dihydro-1H-pyrrol-1-yloxyl-3-yl radical or 2,5,5-trimethylpyrrolidin-1-yloxyl-2-yl radical side-chains, including a lysine mimic azido precursor and their derivatives, are described. The new set of paramagnetic amino acids presented in this work with different (polar. nonpolar. aliphatic, aromatic, etc.) side-chains offers a useful tool for the ESR study of the protein structure and function after incorporation. fulfilling diverse structural requirements.