Chemical characterization of complexation behavior of pertechnetate with cysteine

Protein interactions with bivalent tin. 1. Hydrolysis and complexation of tin(II) ion with glycine

The complexation between tin(II) ion and glycine was studied in 0.15 mol/dm3 NaCl medium at 310 K using potentiometric glass electrode titrations. In the pH range 1.1-4.5 and concentration range of the tin(II) between 0.2 and 5.0 mmol/dm3, with variable glycine-to-tin molar ratio up to 10:1, the experimental data were explained by the formation of the following complexes and their overall stability constants: log(beta +/- sigma): Sn(HGly)+, (12.78 +/- 0.08); Sn(Gly)+, (10.02 +/- 0.07); Sn(OH)Gly, (7.34 +/- 0.03), as well as the pure hydrolytic complex Sn4(OH)2+(6), whose stability constant was determined in separate experiments and found to be -4.30 +/- 0.08, under the same experimental conditions as for complexation study. The precipitate formed in tin(II)-glycine system at pH ca. 5.0 was characterized by chemical and TG analysis, I. R. spectra, X-ray powder diffraction, and electron scanning microscopy measurements. It has been shown that the precipitate has the composition Sn(OH)Gly and crystallizes in a tetragonal system with unit cell dimensions a = b = 1.584 nm, c = 0.597 nm. The mechanism of the complex formation in solution is discussed.

Evaluation of the biodistribution and in vivo biochemistry of 99mTc-cysteine and 99/99mTc-cysteine complexes--a potential renal imaging agent

Cysteine was chelated with 99mTc and/or 99Tc in a freeze-dried kit containing Tin(II) ions, and the yellow 99m/99Tc-cysteine complex (complex I) was separated to study the biodistribution. Comparison of the distribution of 99m/99Tc-cysteine and 99mTc-cysteine complexes was made in rats and mice. The renal excretion patterns were studied in rats in the presence and absence of the renal tubular transport inhibitor 2,4-dinitrophenol. The carrier of Tc-cysteine complex in the blood and also the radioactive compounds in the urine were studied by HPGFC and SDS-electrophoresis. The kidney was confirmed as the target organ; serum albumin serves as a carrier for transport of Tc-cysteine complex to the kidney. The Tc-cysteine complex was the primary form in excreta, and glomerular filtration was the dominant excretory pathway.