ELECTROCHEMICAL TRANSDUCTION IN ELASTIC PROTEIN-BASED POLYMERS - A MODEL FOR AN ENERGY-CONVERSION STEP OF OXIDATIVE-PHOSPHORYLATION

A pair of functional moieties, the carboxyl of an aspartic acid (Asp, D) residue and an N-methyl nicotinamide (NMeN) formed on amide linkage to the epsilon(-)amino group of the lysine (Lys, K) residue, are coup led to perform energy conversion by means of controlling the transitio n temperature, T-t, of a common hydrophobic folding and assembly domai n within the polytricosapeptide, poly[GDGFP GVGVP GVGVP GFGVP GVGVP GV GK{NMeN}P]. The input of electrochemical energy in the form of the red uction of nicotinamide results in a reduction-induced increase in pKa by 2.5 pH units which represents the performance of the chemical work of picking up a proton. The primary structure and the structures of th e oxidized and reduced states are verified by two-dimensional nuclear magnetic resonance. Thus electrochemical transduction, the conversion of electro-chemical energy into chemical energy, has been demonstrated for the first time in a designed, synthetic protein-based polymer. (C ) 1995 Academic Press,Inc.