Binding of quercetin glycosides to Bet v 1 isoforms.

All experiments were performed with 50 μM (Q3OS) or 100 μM (Q3OGlc, Q3OGal) ¹⁵N-uniformly labelled Bet v 1 isoforms at 298 K in 50 mM sodium phosphate buffer, 50 mM NaCl at pH 7.0, and 10% ²H₂O with Bruker Avance 700 MHz and Avance 800 MHz spectrometers. Chemical shift changes were mapped on Bet v 1a (pdb code: 1BV1, grey) or models of Bet v 1d and Bet v 1m as in Fig 2F. Models of Bet v 1d and Bet v 1m were created using the Phyre server [92]. Docked ligands [93] are illustrated in green sticks, oxygen in red. A Overlay of two ¹H-¹⁵N HSQC spectra of Bet v 1a in the absence (black) and presence of a 15-fold excess of Q3OS (red). B Disappearing resonances after addition of Q3OS mapped on Bet v 1a in red. Q3OS is docked inside the hydrophobic pocket [17]. C Mapping of chemical shift changes of (weak) Q3OClc or D (strong) Q3OGal interaction on Bet v 1a. E Overlay of two ¹H-¹⁵N HSQC spectra of Bet v 1d in the absence (black) and presence of a 15-fold excess of Q3OS (red) and F occurring chemical shift changes mapped on a model of Bet v 1d. Weak affinity is observed for interaction of Bet v 1d with G Q3OGlc of H Q3OGal. I Overlay of two ¹H-¹⁵N HSQC spectra of Bet v 1m in the absence (black) and presence of a 15-fold excess of Q3OS (red) and J occurring chemical shift changes mapped on a model of Bet v 1m. High affinity is observed for the interaction of Bet v 1m with K Q3OGlc and L Q3OGal. Regions of the ¹H-¹⁵N HSQC spectra during titration of Bet v 1d or Bet v 1m with Q3OGlc and Q3OGal are provided in the S1 Fig