PECULIARITIES IN THE FORMATION OF X-RAY FLUXES BY WAVEGUIDE–RESONATORS OF DIFFERENT CONSTRUCTION
Optics and Spectroscopy (English translation of Optika i Spektroskopiya). Том 124. 2018. С. 838-849
A series of linear peptides with the general formula H-Glu(R1)-Glu(R2)-OH was subjected to cyclization under standard conditions. Formation of respective 2,5-diketopiperazines was accompanied by transformation of the N-terminal Glu(R1) to pyroglutamic acid residue. Even in the case R1 is an amino acid residue attached to the N-terminal γ-carboxyl group, lactamization leads to its elimination. The observed reaction has not been reported so far in the literature. Correspondingly, an alternative route to Glu(R1)-Glu(R2)-containing 2,5-diketopiperazines was applied to improve the overall yields. Copyright © 2018 European Peptide Society and John Wiley & Sons, Ltd.