Long-range electron transfer (ET) across peptide chains with different secondary structures in pa-(gly)(n=0-6)-aa (pa = C6H4(CO)(2)N(CH2CO), gly = glycine, aa = HNCH2COOCH3) ionic molecules has been explored by computational studies of ET matrix element, reorganization energy and rate constant using two-state variational method (TSVM) and classical rate model. For comparison, electron correlation effects are examined in the studies. Calculated results are then used to elucidate ET reaction mechanisms. (C) 2007 Elsevier B.V. All rights reserved.