Fig. 7
Dual recognition mode of LIP for cancer cells. (a) Binding mode of LIP with the disaccharides of Neu5Gc coupled with 2,6-galactose and 2,3-galactose at the N-terminal domain. The disaccharide and the key residues that interacted with it are shown in sticks and colored yellow and green, respectively. The LIP protein is shown in a cartoon representation in green. (b) Binding mode of LIP with SM at the C-terminal module. SM is shown as rainbow spheres. LIP protein is shown in cartoon and surface representations and colored cyan. The key residues that interacted with SM are labeled, shown in stick representation and colored green. (c) Fluorescence spectra of LIP under different conditions. The LIP stock solutions and N003G or SM stock solutions, respectively, were mixed in phosphate buffer. The resultant mixture was equilibrated for 2 min before recording the steady-state fluorescence spectrum, and the emission spectra were obtained at wavelengths ranging from 290 to 495 nm. Values are the means of five independent experiments. (d) Rapid kinetics of the binding of N003G to LIP. Stopped-flow fluorescence measurements of the binding of N003G to LIP. The experiment was performed in PBS at 25 °C. All data sets were analyzed simultaneously with proper weighting to yield best-fit parameters. K1 = 24.925540 s− 1, K2 = 2.128309 ± 0.055980 s− 1, K3 = -0.0063 s− 1