Slow tert-butyl ester acidolysis and peptide 3(10)-helix to alpha-helix transition in HFIP solution.
We have already shown by CD and NMR techniques that the terminally protected homo-octapeptides Z (and Ac)-[L-(alphaMe)Val](8)-OtBu undergo a slow and irreversible 3(10)-helix to alpha-helix transition when dissolved in 1,1,1,3,3,3-hexafluoroisopropanol. In the present work, we find by HPLC and CD that under the aforementioned experimental conditions, a slow acidolysis of the tert-butyl ester functionality does take place affording the corresponding octapeptide free acids. The results of our combined chromatographic and spectroscopic experiments are confirmed by a comparison with the properties of independently synthesized and chemically characterized authentic compounds.
Moretto
Alessandro
A
Department of Chemistry, Institute of Biomolecular Chemistry, CNR, University of Padova, Padova, Italy.
Crisma
Marco
M
Formaggio
Fernando
F
Kaptein
Bernard
B
Broxterman
Quirinus B
QB
Keiderling
Timothy A
TA
Toniolo
Claudio
C
D002851:Chromatography, High Pressure Liquid; D002942:Circular Dichroism; D004952:Esters / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D010455:Peptides / Q000737:chemistry*; D020005:Propanols; D017433:Protein Structure, Secondary; D012996:Solutions; D017550:Spectroscopy, Fourier Transform Infrared; D006845:Hydrocarbons, Fluorinated
D004952:Esters; D010455:Peptides; D020005:Propanols; D012996:Solutions; C001337:hexafluoroisopropanol; D006845:Hydrocarbons, Fluorinated