Figure 3.

HSQC Titration Data Highlights Multiple Binding Sites in Both FBN1 and LTBP1

Titrations were carried out by sequential addition of lyophilized unlabeled protein to ¹⁵N-labeled protein samples and monitored using ¹H-¹⁵N HSQC spectra.

(A and B) Peaks were observed to shift in titrations of (A) ¹⁵N-LTBP1^cbEGF14TB3 with FBN1^E2cbEGF1 added, or of (B) ¹⁵N-FBN1^E2cbEGF1 with LTBP1^cbEGF14TB3 added. The combined ¹H^N and ¹⁵N chemical shift change is plotted as a function of protein sequence.

(C and D) Peak broadening was observed in titrations of (C) ¹⁵N-LTBP1^E3cbEGF15 with FBN1^E2cbEGF1 added or of (D) ¹⁵N-FBN1^E2cbEGF1 with LTBP1^E3cbEGF15 added. Peak intensity changes, measured as the ratio of peak intensity in the absence of ligand to that in the presence of ligand, are plotted as a function of protein sequence. Error bars are determined from the effect of background noise on peak height (SD). Gaps in the plots occur for residues with unassigned or very weak peaks in the HSQC or for prolines.