Chromatographic Evidence on the Occurrence of Thiotaurine in the Urine of Rats Fed with Cystine

n/

THE ISOLATION OF PURE HYPOTAURINE FROM THE URINE OF RATS FED CYSTINE

n/

The enzymatic oxidation of cysteamine to hypotaurine. Purification and properties of the enzyme.

The enzyme oxidizing cysteamine to hypotaurine has been extracted from horse kidney and purified. The final product behaves as a single protein when analyzed in the ultracentrifuge, by starch gel electrophoresis, and by filtration on dextran gels. The sedimentation coefficient of the pure product is s20, w = 5.9. The molecular weight determined by the Yphantis procedure (22) is 83,000. Nonheme iron is contained in the amount of 1 atom per molecule of enzyme. Spectrophoto-metric analyses indicate absence of nonprotein chromophores in the visible and in the near ultraviolet range. The complete amino acid composition has been determined by ion exchange chromatography. The effect of sulfide, methylene blue, and hydroxylamine, which act as cofactor-like compounds, has been studied. Of the substrates assayed (cysteamine, cysteine, cysteine ethyl and methyl esters, and reduced glutathione), only cysteamine is oxidized to the sulfinic derivative in the presence of the cofactor-like compounds named

Preparation and properties of the decarboxylated dimer of aminoethylcysteine ketimine

A simple procedure for the preparation of the aminoethylcysteine ketimine decarboxylated dimer in gram amounts is presented and some relevant properties of the product are reported

Some new details of the copper-hydrogen peroxide interaction

The addition of neocuproine (NC) or bathocuproine-disulphonate at the end of the autooxidation of Cu-I in phosphate buffer, pH 7.4, regenerates almost entirely the O-2 consumed. Other chelating agents assayed, including o-phenanthroline, cannot replace NC in promoting the O-2 formation. O-2 is also produced by adding NC to a mixture of Cu-II and H2O2 Concomitant with the O-2 evolution, the typical absorbance of the (NC)(2)Cu-I complex appears to account for the complete reduction of Cu-II to Cu-I. It is concluded that the addition of H2O2 with Cu-II produces the equilibrium Cu-II(O2H)(-) (CdO2H)-O-I.. Addition of NC shifts the equilibrium to the right side by binding CuI. The released O-2(.-) then reacts with the remaining Cu-II yielding, in the presence of NC, the net reaction of 4 NC + 2 Cu-II + H2O2 --> 2 (NC)(2)Cu-I + O-2 + 2 H+. O-2 is also released in the absence of added NC provided the H2O2 concentration is increased. In these conditions the Cu-II(O2H)(-) complex undergoes other reactions leading to the copper-catalysed decomposition of H2O2. (C) 1997 Academic Press

INFLUENCE OF DIET ON CYSTATHIONINE KETIMINE AND LANTHIONINE KETIMINE CONTENT IN HUMAN URINE

[No abstract available

THE INHIBITION OF BOVINE SERUM AMINE OXIDASE BY CYSTEAMINE

Bovine serum amine oxidase (BSAO) is inhibited by cysteamine, while cystamine is a good substrate. The activity of BSAO is not restored following removal of excess cysteamine by N-ethylmaleimide, by iodoacetate or by filtration through a G-25 Sephadex column