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The taurine (Tau) containing N‐protected pseudotripeptide isopropylamide Z–Tau–Pro–D‐Phe–NHiPr (1) has been specifically designed and synthesized as suitable model to test the ability of the sulfonamido group to participate as H‐bond acceptor to a type II β‐turn and to get information on the preferred rotameric conformation around the S—N bond and the hybridization state of the nitrogen atom. The present structural investigation reveals that, although the sulfonamide junction is invariably folded in a gauche mode, the β‐turn structure, stabilized by the 4 → 1 hydrogen bond, is not found in the crystal and the sulfonamido oxygen atoms are not involved in any intra‐ or intermolecular hydrogen‐bond interaction. More than one conformer populates the CDCl3 solution with only a minor contribution by the expected β‐turn. The Pro nitrogen is significantly pyramidalized and the nitrogen lone pair points in opposite direction to that of the Pro CαH bond thus adopting R chirality, in an arrangement practically identical to that found in the previously studied homochiral analogue Z–Tau–Pro–Phe–NHiPr. © 2000 John Wiley & Sons, Inc. Biopoly 54: 379–387, 2000

An efficient synthesis of the backbone modified glutathione analogue gamma-(L-gamma-oxaglutamyl)-L-cysteinyl-glycine (7), characterized by the presence of an urethane O-CO-NH linkage replacing the gamma-glutamylic CH2CO-NH fragment is described. The new analogue has been fully characterized by 1H- and 13C-NMR, and FAB-MS. Compound 7 was tested for inhibition of gamma-glutamyl-transferase activity and was found to be a non-competitive inhibitor of hog kidney gamma-glutamyltransferase (EC 2.3.2.2).

No abstract

The taurine (Tau) containing tripeptide derivative Z‐Tau‐Pro‐Phe‐NHiPr (1) has been synthesized as suitable sulfonamido‐pseudopeptide model to investigate formation and conformational properties of folded secondary structures stabilized by intramolecular H bonds directly involving the sulfonamide junction. In the crystal the pseudopeptide 1 adopts a type I β‐turn with the Pro and Phe residues located at the (i + 1) and (i + 2) corner positions, respectively. The turn is stabilized by a 4 → 1 H bond engaging one of the SO2 oxygen atoms and the isopropylamide NH. In CDCl3 solution the β‐turn folding is accompanied by a γ‐turn centered at the Pro and involving a 3 → 1 H bond between the SO2 and the Phe NH. A comparison of the structural and conformational properties found in 1 with those of the already known sulfonamido‐pseudopeptides, with particular reference to the models containing the Tau‐Pro junction, is also reported. © 1997 John Wiley & Sons, Inc. Biopoly 41: 555–567, 1997.