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In the legend for Figure 4b and in the last line of paragraph 6 in Methods, “number of moles” should be moles. Also in Methods, paragraph 3, “superfolder GFP (27.747 kDa/mole)...” should read “superfolder GFP (27747 g/mole)” and “folding reporter GFP (27.742 kDa/mole)...” should read “...folding reporter GFP (27,742 g/mole).” The error has been corrected in the PDF version of the article.