pH dependence of URN1-FF conformational properties.

<p>Protein samples were prepared at 20 µM and were immediately measured by (<b>a</b>) far-UV CD, (<b>b</b>) tryptophan intrinsic fluorescence and (<b>c</b>) ANS fluorescence at 298 K. The fluorescence emission spectrum of ANS in the absence of protein is represented as a dotted line. URN1-FF species were at pH 2.0 (squares), pH 2.5 (diamonds), pH 3.0 (circles), and pH 5.7 (triangles). (<b>d</b>) One-dimensional NMR (¹H-NMR) spectra of URN1-FF were recorded at 298 K and 600 MHz, using a protein concentration of 35 µM. Two different spectra were collected, at pH 5.7 (above) and pH 2.5 (below).