Biological activity and conformational isomerism in position 9 analogues of the des-1-tryptophan,3-beta-cyclohexylalanine-alpha-factor from Saccharomyces cerevisiae.
Analogues of the des-1-tryptophan,3-beta-cyclohexylalanine-alpha-factor of Saccharomyces cerevisiae, where the glycyl residue of position 9 was replaced by D-Ala, L-Ala, D-Leu, and L-Leu, were synthesized and evaluated by morphogenesis assays and circular dichroism spectroscopy. Synthesis was accomplished in solution phase with mixed anhydrides and p-nitrophenyl active esters as the coupling agents. All crude dodecapeptides were purified to greater than 98% homogeneity by preparative high-performance liquid chromatography on a reversed-phase column. The Gly9, D-Ala9, and D-Leu9 analogues elicited morphogenic alterations in MATa strains of S. cerevisiae at concentrations of 1-2 micrograms/mL and exhibited similar CD patterns in both trifluoroethanol and tris(hydroxymethyl)aminomethane buffer, pH 7.4. In contrast, the L-Ala9 and L-Leu9 analogues were more than 200 times less active in the morphogenesis assay and had markedly different CD spectra. These results demonstrate that the position 9 residue plays an important role in determining the biological activity and solution conformation of alpha-factor. We suggest the presence of a type II beta-turn in the Lys7-Gln10 region when the alpha-factor assumes its biologically active conformation.
D000409:Alanine / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000494:pharmacology; D002851:Chromatography, High Pressure Liquid; D002942:Circular Dichroism; D007202:Indicators and Reagents; D009682:Magnetic Resonance Spectroscopy; D000072235:Mating Factor; D009024:Morphogenesis; D009904:Optical Rotation; D010455:Peptides / Q000138:chemical synthesis* / Q000494:pharmacology; D011487:Protein Conformation; D012441:Saccharomyces cerevisiae / Q000187:drug effects* / Q000502:physiology; D013329:Structure-Activity Relationship
D007202:Indicators and Reagents; D010455:Peptides; D000072235:Mating Factor; D000409:Alanine