Fluorescence resonance energy transfer in short linear peptides carrying 3-[2-(2-benzofuranyl)benzoxazol-5-yl]-alanine and 3-nitro-l-tyrosine molecules in poly(vinyl alcohol) film

Excitation energy transfer between donor (Box(benzfur)) and acceptor (Tyr(NO₂)) is studied for uniaxially stretched and unstretched poly(vinyl) alcohol films. Free D-A pair and short linear peptides are examined. D-A distance for the longest peptide in unstretched poly(vinyl alcohol) film is very similar to that determined in aqueous solution which indicates the immobilization of the peptide native conformation chain in PVA. The results for stretched PVA matrix indicate partial stretching of the peptide chain. However, for free non-linked D-A pair for stretched PVA matrix substantial increase of D-A distance is observed. Emission anisotropy increases with the degree of stretching but for the longest peptide the saturation effect is not reached. Moreover, the donor emission anisotropy spectra remain practically constant for a given stretching factor R_S of the film.