The results of electron transfer reactions between enantiomeric oxidant systems, formed by [Fe(tetpy)(OH)₂]⁺ ions (tetpy = 2,2‘,2”,2‘”-tetrapyridine) anchored to poly(L-glutamate) or poly(D-glutamate), and L-dihydroxy substrates at pH 7 are reported. Stereoselectivity is observed only when the formation of precursor complexes satisfies specific steric requirements. It is chiefly due to transition state effects, the ratio of the unimolecular rate constants of the elementary electron-transfer step of the diastereomeric processes, k_{et DL}/k_{et LL}, being definitely higher than K_DL/K_LL, where K_{DL (LL)} is the apparent formation constant of the diastereomeric adducts. Solvent reorganization energy changes, associated with the diastereomerically related charge transfer steps, were calculated by the ellipsoidal cavity model for short-range electron transfer. These changes were found to be a major contributor to kinetic discrimination, reflecting the stereochemical control exerted by the ordered polypeptide matrices in the formation of diastereomeric pairs. The results of long-range electron transfer in systems formed by donor-acceptor pairs covalently bound to ε-amino groups of poly(L-lysine) are also reported. The pairs are protoporphyrin IX and naphthalene, whose photophysical behavior was investigated by steady-state and time resolved fluorescence as a function of pH. Intramolecular electron transfer only occurs between ground-state porphyrin and excited naphthyl chromophores, provided the polypeptide is in α^--helical conformation. Implications of the structural features of the system investigated on the observed phenomena are briefly discussed.