Analysis of the ¹H–¹⁵N HSQC spectra of S100B in complex with the unlabeled S100A1.

<p>(A) Overlapped NMR HSQC spectra of ¹⁵N-S100B in black and ¹⁵N labeled S100B complex with unlabeled S100A1 in a 1:1M ratio (red). Residues displaying significant intensity decreases and those with perturbed chemical shifts are framed by boxes (green and blue, respectively).</p> <p>(B) Bar plot showing the changes in the intensity ratio (I/I0) comparing the ¹⁵N S100B and the complex of ¹⁵N S100B with S100A1. The blue line shows the threshold of selected residues that display a notably reduced intensity.</p> <p>(C) Bar plot presenting the changes in chemical shift perturbation comparing free ¹⁵N S100B and the ¹⁵N S100B in complex with Ca²⁺-bound S100A1. The blue line shows the threshold of selected residues that display a notable perturbation.</p> <p>(D) Ribbon (stick) diagram of the S100B in red obtained using the PyMOL program. The residues that show chemical shift perturbations and intensity decreases are shown in blue.