Bioactive and model peptides characterized by the helicogenic (αMe)Phe residue

Abstract We have synthesized and fully characterized the hypersweet super- aspartameanalogue p CN-C 6 H 4 -NHCO-L-Asp-L-(αMe)Phe-OME 1 ; the [D-(αMe)Phe] 3 -analogue of the formyl-methionyl tripeptidechemoattractant HCO-L-Met-L-Leu--D-(αMe)Phe-OMe 2 , the first D- chemotactic peptidebeing found more active than its L- diastereomer; and the model pentapeptide p BrBz-D-(αMe)Phe-(Aib) 2 -D-(αMe)Phe-Aib-O t Bu 3 . The preferred conformation of the three peptides, as determined by X-ray diffraction analyses, is discussed in terms of the proposed receptor models for sweet perception [peptide 1 ] and neutrophil chemotaxis[peptide 2 ], and as a promising candidate for molecular recognitionstudies [peptide 3 ].