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. Author manuscript; available in PMC: 2009 Jul 23.
Published in final edited form as: J Am Chem Soc. 2008 Jun 25;130(29):9260–9267. doi: 10.1021/ja800736h

Figure 3.

Figure 3

Dynamic properties and hydration water number of designed contrast agents. (a) S2 order values of the engineered metal binding protein. The positions of ligand residues are shown in vertical bars. Order parameters of CA1-CD2 with discontinuous ligand residues have the same dynamic properties as the scaffold protein. Arrows indicate the position of ligand residues. (b) Measurement of coordination water number by monitoring Tb3+ life time. Luminescence decay lifetime was obtained by fitting the acquired data in both H2O and D2O with a mono-exponential decay function. A standard curve correlating the Δkobs with water number (q) was established by using well-characterized chelators, such as EDTA (q=3), DTPA (q=1), NTA (q=5), and Aquo Tb3+ (q=9) solution with R2=0.997.38, 39 Water numbers coordinated to Tb3+-protein complexes were then obtained by fitting the acquired Δkobs value to the standard curve.