Model protein machines motion produced

Polymers III through VI represent a systematic increase in the number of Val (V) residues replaced by more oil-like Phe (F) residues. Each step increase in oil-like character of the model protein, on going from 0 to 2 to 3 to 4 and to 5 Phe residues for every 30 residues, stepwise increases the affinity of Na for -COO . Each step increase in oil-like character means that less of an increase in salt is required to drive contraction. Polymer VI, when cross-linked into elastic sheets, provides the most efficient molecular machine of the set. This molecular machine requires less chemical energy to produce a given amount of motion, that is, to perform a given amount of mechanical work. 

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