NONLINEAR HYDROPHOBIC-INDUCED PK(A) SHIFTS - IMPLICATIONS FOR EFFICIENCY OF CONVERSION TO CHEMICAL ENERGY

By using one Asp or one Glu per thirty residues in a polytricosapeptid e capable of exhibiting a hydrophobic folding and assembly transition and stepwise converting a set of the five Val residues (most proximal to the Asp or Glu residue) to more-hydrophobic Phe residues, a non-lin ear hydrophobic-induced pK(a) shift was observed with a Delta pK(a) of 0.4 (Asp) and 0.3 (Glu) on addition of 2 Phe residues per 30mer but w ith a Delta pK(a) of 4.7 (Asp) and 2.7 (Glu) on going from 4 Phe/30mer to 5 Phe/30mer. As a shift in pK(a) can be equivalent to the conversi on to chemical energy from whatever energy input mechanical, chemical, electrochemical, pressure or light - which effects a change in hydrop hobicity, the non-linear hydrophobic-induced pK(a) shift means increas ed efficiency of energy conversion with increased hydrophobicity of th e protein-based polymer.