Lanthanide probe

Tweedle, M. F. Relaxation Agents in NMR Imaging. In Lanthanide Probes in Life, Chemical and Earth Sciences Theory and Practice Btinzli, J.-C. G., Choppin, G. R., Eds. Amsterdam Elsevier, 1989 p 127. 

Selvin, P.R. (2002) Principles and biophysical applications of luminescent lanthanide probes. Annu. Rev. Biophys. Biomol. Struct. 31, 275-302. 

Soini, E., and Lovgren, T. (1987) Time-resolved fluorescence of lanthanide probes and applications in biotechnology. CRC Crit. Rev. Anal. Chem. 18, 104-154. 

For protein and DNA studies several methods of locating the lanthanide probe onto the chain have been employed. In one example the antenna fluorophore is covalently attached to one leg of the chelate of europium or terbium, which is further attached to the specific site through thiol reactive, e.g. maleimide, or amine reactive, e.g. A-hydroxysuccinimide, groups. A typical example is shown in (3.77). ... 

The use of lanthanide probes for structure determination in small molecules has been extensively emphasized. In practice, bond lengths and angles are taken from crystallographic data, and the rotation angles about single bonds are determined from the nmr studies. The results of small molecule studies have been reviewed elsewhere.7,8... 

As with X-ray crystallography, as the molecular weight of the molecule increases, the difficulties in performing structural studies increase. The lanthanide probe method has so far been applied in great detail to only one protein, lysozyme.5 The nuclei studied were protons. Because of the complexity of the protein nmr spectrum, it was necessary to apply techniques to resolve and simplify the spectrum and to assign the observed resonances to specific nuclei in the molecule. Table III lists some details of these methods, with references. 

Biinzli J-CG (1989) In Biinzli J-CG, Choppin GR (eds) Lanthanide probes in life, chemical and earth sciences theory and practice. Elsevier, New York, p 219... 

C6 glioma cells with the Eu3+ complex (10-500 pM, 45 min and 1 h at 37 °C) provided clear images consistent with the localization of the complex at mitochondria. Incubations of the cells at 4 °C, on the other hand, resulted in no probe uptake by the cells, which indicated that the lanthanide probe entered the cells through some biological activities. Finally, the authors performed luminescence and MR imaging experiment by using cocktail mixtures of Eu3+ and Gd3+ complexes (for example, Eu3+ Gd3+ = 40 60), and successfully obtained nice luminescence and MR images from the same population of C6 cells. 

Anion sensing using visible-emitting lanthanide probes has proven successful (Tsukube et al., 2006) and this work is now being extended to Ybm probes, particularly for the detection of thiocyanate. The latter is the principal metabolite of cyanide anion and exists in human serum, saliva, and urine. The luminescent probe is a complex of hexadentate tetrakis(2-pyridylmethyl)ethylenediamine (tpen, see fig. 119) which bears two water molecules, [Yb(tpen)(H20)2](0tf)3. In absence of anion coordination, the 980-nm luminescence is quenched, but the replacement of the water molecules with thiocyanate or other anions such as acetate, nitrate or halogenides removes the quenching, which makes the complex a responsive probe. The largest effect (a six-fold increase in luminescence) is obtained for thiocyanate, followed by acetate and nitrate (3.5-fold) and chloride (two-fold). 

Bunzli, J.-C.G., 2004. Luminescent lanthanide probes as diagnostic and therapeutic tools. In Sigel, A., Sigel, H. (Eds.), Metal Complexes in Tumor Diagnosis and as Anticancer Agents, vol. 42. Marcel Dekker, New York, pp. 39-75 (chapter 2). 

Biinzli, Jean-Claude G., and Choppin, Gregory R., eds. (1989). Lanthanide Probes in Life, Chemical and Earth Sciences. New York Elsevier. 

Hanaoka, K., Kikuchi, K., Kojima, H., et al. (2003) Selective detection of zinc ions with novel luminescent lanthanide probes. Angewandte Chemie International Edition, 42, 2996-2999. 

Hanaoka, K., Kikuchi, K., Kobayashi, S., and Nagano, T. (2007) Time-resolved long-lived luminescence imaging method employing luminescent lanthanide probes with a new microscopy system. Journal of the American Chemical Society, 129, 13502-13509. 

The vitamin B12 and related coenzymes (cobalamins, cobinamides, and corrinoids) have been studied in detail using H and shift and relaxation studies. (595-598) With the aid of lanthanide probes the eonformations of cobalamins in solution are shown to be very similar to those in the crystalline state. The appreciable temperature dependences of the electronic and H NMR spectra are attributed to a conformational change rather than to a 6-eoordinate-5-coordinate equilibrium as previously suggested. (599) The binding of 5 -ATP to the respiratory protein hemoeyanin has been studied by H and NMR. 

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