Fig. 6: Determination of the absolute configuration of LJ3a and LJ3b by NMR spectroscopy.
From: Genuine selective caspase-2 inhibition with new irreversible small peptidomimetics
a Heteronuclear Multiple Quantum Coherence (HMQC) for LJ3a. Two-dimensional (2D) 1H–15N 2D heteronuclear HMQC spectrum of the LJ3a sample showing the correlation between the nitrogen and the proton it carries. The spectrum shows additional peaks due to the racemization of P1 and corresponding to two different isomers. The assignment has been made and the correlations for one isomer are represented in thin letters while the other is in bold. b HMQC for LJ3b. 2D 1H–15N 2D heteronuclear HMQC spectrum of the LJ3b sample showing the correlation between the nitrogen and the proton it carries. The spectrum shows additional peaks due to the racemization of P1 and corresponding to two different isomers. The assignment has been made and the correlations for one isomer are represented in thin letters while the other is in bold. c LJ3a molecules of general formula Qco-P5-P4-P3-P2-P1-OPh with racemization in P1 (Asp-OPh) and absolute configuration R in position P2 (3-neopentyl proline). The positions P5 (Val 5), P4 (Asp 4), and P3 (Val 3) have an absolute configuration S. d Structural 3D model of the 1S2R isomer. e Structural 3D model of the 1R2R isomer. f LJ3b molecules of general formula Qco-P5-P4-P3-P2-P1-Oph with racemization in P1 (Asp-OPh) and absolute configuration S in position P2 (3-neopentyl proline). The positions P5 (Val 5), P4 (Asp 4), and P3 (Val 3) have an absolute configuration S. g Structural 3D model of the 1S2S isomer. h Structural 3D model of the 1R2S isomer.
